Knuckle for self-steering axle / suspension system

Abstract

A knuckle (200) for a heavy vehicle self-steering axle / suspension system, the knuckle including an integrally formed structure (270) for mounting components of a drum brake system. The knuckle (200) includes a kingpin (264) welded directly to the knuckle (200) and a separate drag link arm (290) bolted to the knuckle.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 126,193, filed on December 16, 2020. Technical Field

[0003] This disclosure generally relates to axle / suspension systems for heavy-duty vehicles. More specifically, this disclosure relates to self-steering axle / suspension systems for heavy-duty vehicles. More specifically, this disclosure relates to a steering knuckle for a self-steering axle / suspension system for heavy-duty vehicles, the steering knuckle comprising an integrally formed structure for mounting components of a drum braking system, which eliminates the complex manufacturing processes and components required for preparing the spindle end of the steering knuckle to enable mounting of a separate brake spider, and for machining multiple engagement points on the spindle end to position and attach the separate brake spider, thereby reducing manufacturing complexity and cost. The steering knuckle includes a spindle that is forged, machined, and then directly friction-welded to the steering knuckle using only a single friction weld joint, eliminating the need to attach the spindle to the steering knuckle using multiple weld joints, thereby reducing manufacturing costs and increasing the overall strength of the spindle. Furthermore, by integrating the structure for mounting drum brake system components into the steering knuckle, the distance from the kingpin to the bearing shoulder of the main shaft is minimized, and thus the distance from the kingpin to the vertical centerline of the wheel (attached to the hub, which is rotatably mounted on a bearing attached to the main shaft) is minimized. This reduces stress on the steering knuckle and on the pivot connection between the steering knuckle and the end component of the steerable axle, thereby increasing overall strength and reducing fatigue in the steering knuckle and the pivot connection between the steering knuckle and the steerable axle, and reducing the risk of potential premature failure of the steering knuckle and / or the pivot connection between the steering knuckle and the steerable axle. Additionally, the steering knuckle includes separate tie rod arms bolted to it via axial and radial bolts, which minimizes the overall size and weight of the steering knuckle while providing a robust structure to resist overload conditions and reducing the overall weight of heavy vehicles, providing the desired steering angle for the steering knuckle and the mounted wheel, and providing a robust structure for use on self-steering axle / suspension systems with different components and constructions. Background Technology

[0004] Self-steering axle / suspension systems for heavy-duty vehicles are well known in the art. Heavy-duty vehicles include trucks and tractor-trailers or semi-trailers, and their trailers. Each heavy-duty vehicle typically includes a frame from which at least one axle / suspension system (e.g., a self-steering axle / suspension system) is suspended. In recent years, self-steering axle / suspension systems have become quite popular, particularly in the medium and heavy-duty truck and semi-trailer industries. When in a lowered or operating position, such a self-steering axle / suspension system is typically used to distribute the load borne by the axles of a heavy-duty vehicle. When the heavy-duty vehicle is lightly loaded or unloaded, the self-steering axle / suspension system typically employs a lifting system and can be lifted such that the tires associated with the self-steering axle / suspension system do not contact the ground or road surface. Self-steering axle / suspension systems can also be of a non-liftable type. When a self-steering axle / suspension system is in a lowered or operating position with the tires in contact with the ground or road surface, the self-steering feature provides a mechanism that allows the tires to better follow the driving path when a heavy vehicle is cornering, while still helping to bear the load of the heavy vehicle. In trailing arm self-steering axles / suspension systems, it is known that if the steerable axle is mounted with an appropriate pitch or caster angle, the resistance of the mounted wheels will cause the steerable axle to automatically steer in response to the vehicle's steering.

[0005] Such self-steering axle / suspension systems are generally similar in the following respects: Each self-steering axle / suspension system typically includes a steerable axle having a central axle tube supported by a pair of laterally spaced trailing arm beams, which are welded or otherwise rigidly attached to the central axle tube. Each trailing arm beam is pivotally connected at its front end to a corresponding frame hanger in a pair of laterally spaced frame hangers, which in turn are rigidly attached to and suspended from a corresponding main member of the heavy vehicle frame. A self-steering axle / suspension system typically includes a pair of shock absorbers and a pair of air springs. Each shock absorber extends between a corresponding beam in the axle and its corresponding hanger or main member of the heavy vehicle frame, and is mounted on and attached to the corresponding beam. Each air spring extends between the rear end of a corresponding beam in the axle and the corresponding main member of the heavy vehicle frame, and is mounted on the rear end of the corresponding beam and the corresponding main member of the heavy vehicle frame. Shock absorbers and air springs together provide the desired driving characteristics for self-steering axle / suspension systems, and thus for heavy-duty vehicles.

[0006] To allow wheel steering of the steerable axle attached to a self-steering axle / suspension system, the steerable axle also includes a pair of end members attached to respective outer ends of the center axle tube by suitable means (e.g., welds). The self-steering axle / suspension system also includes a pair of prior art steering knuckles pivotally connected to the respective end members of the steerable axle by kingpins configured to pass through vertically aligned openings formed in the steering knuckles and end members. Each prior art steering knuckle includes a spindle end rigidly attached to the outer surface of the steering knuckle by any suitable means (e.g., welds or fasteners). A wheel end assembly is rotatably mounted on the spindle end in a manner known in the art. More specifically, the wheel end assembly includes a bearing assembly having an inner bearing and an outer bearing mounted on the outer end of the spindle end. A spindle nut assembly is threaded onto the outer end of the spindle end and secures the inner and outer bearings in place. It is known that the hub of the wheel end assembly is mounted on the inner and outer bearings for rotation relative to the spindle end. A hubcap is mounted on the outer end of the wheel hub and closes the outer end of the wheel hub, thus closing the outer end of the wheel end assembly. A single rim or a pair of rims (depending on the specific design considerations of the wheel end assembly) is mounted to the wheel hub using multiple threaded fasteners or studs and mating nuts. As is well known, tires are mounted on individual rims. For the purposes of this disclosure, the rim, together with the tire on which it is mounted, is collectively referred to as a “wheel”.

[0007] Each prior art steering knuckle includes a pivot arm or tie rod arm forming a pair of longitudinally spaced openings. A tie rod is pivotally connected to the rearmost opening of the pair of openings by fasteners. A coil over spring is fastened at its first end to the frontmost opening of the tie rod arm by fasteners. The second end of the coil over spring is connected to a bracket, which is in turn connected to the center axle tube of the steerable axle by any suitable means (e.g., welds and / or fasteners).

[0008] When a wheel mounted on a prior art steering knuckle turns, the steering knuckle pivots about the kingpin relative to the end member of the steerable axle. When the wheel turns toward the driver's side of the vehicle to turn left forward, the driver's side steering knuckle pivots about the driver's side end member of the steerable axle via a pivoting connection through the kingpin to the end member, while the passenger side steering knuckle pivots about the passenger side end member of the steerable axle away from the passenger side end member via a pivoting connection through the corresponding kingpin to the end member. Conversely, when a wheel mounted on a prior art steering knuckle turns toward the passenger side of the vehicle to turn right forward, the driver's side steering knuckle pivots about the driver's side end member of the steerable axle away from the driver's side end member via a pivoting connection through the kingpin to the end member, while the passenger side steering knuckle pivots about the passenger side end member of the steerable axle via a pivoting connection through the corresponding kingpin to the end member. Because the driver's side steering knuckle and the passenger side steering knuckle are connected to each other via tie rods, each wheel attached to its respective axle end remains substantially parallel to each other during right-forward and left-forward turns. Specifically, when the vehicle is turning right-forward, the passenger-side wheels steer at a slightly greater angle than the driver-side wheels, and when the vehicle is turning left-forward, the driver-side wheels steer at a slightly greater angle than the passenger-side wheels. This self-steering axle / suspension system helps in maneuvering heavy vehicles during cornering.

[0009] Self-steering axle / suspension systems are typically combined with drum braking systems to provide braking for heavy-duty vehicles. When used with self-steering axle / suspension systems of heavy-duty vehicles, components of the drum braking system are typically integrated into or mounted on components of the self-steering axle / suspension system (e.g., the spindle end of a prior art steering knuckle). A drum braking system typically includes a pair of drum brake assemblies integrated into respective outer ends of the self-steering axle / suspension system. More specifically, each drum brake assembly typically includes a brake drum attached to the hub of a wheel end assembly rotatably mounted on the outer end of the spindle end of a corresponding prior art steering knuckle. The drum braking system also includes a pair of brake shoes housed within and radially spaced from the inner braking surface of the brake drum. The brake shoes are pivotally connected to a separate brake chassis fixedly attached to the spindle end inside the wheel end assembly. Each brake shoe is connected to a corresponding roller at its end opposite the pivot connection. An S-shaped cam attached to the outer end of the camshaft assembly, which is attached to the steering knuckle, engages with the roller to actuate the brake shoe.

[0010] During operation, when the drum brake system of a heavy vehicle is pressurized and actuated, for example, by a brake chamber operably connected to the camshaft, the camshaft rotates, thereby causing the S-shaped cam to rotate. The rotation of the S-shaped cam overcomes one or more brake return springs connected between the brake shoes, pushing the brake pads of the brake shoes radially outward, causing them to contact the inner brake surface of the brake drum, thus generating friction to slow or stop the heavy vehicle. Once the drum brake system is no longer actuated, the camshaft (and therefore the S-shaped cam) rotates back, allowing the brake return spring(s) to re-establish a radially spaced relationship between the brake pads of the brake shoes and the inner brake surface of the brake drum.

[0011] While prior art steering knuckles for self-steering axle / suspension systems are generally suitable for their intended purpose, they have certain drawbacks, defects, and limitations. For example, when the self-steering axle / suspension system employs a drum braking system, such prior art steering knuckles typically use a separate brake chassis, which is welded or otherwise rigidly attached to the spindle end of the steering knuckle. The use of such a separate brake chassis typically involves a complex manufacturing process that first requires cutting and removing the axle end from the straight shaft of the spindle, which has a friction mount to the center tube, such that the axle end includes the spindle and a portion of the center tube, referred to herein as the "spindle end." Multiple joints can be machined on the spindle end to allow for the positioning of the separate brake chassis. The spindle end is then welded or otherwise rigidly attached to the body of the prior art steering knuckle. The separate brake chassis is then positioned and welded to the spindle end between the location of the rotatably mounted hub of the inner bearing assembly and the inner end of the spindle end. The complex manufacturing process required to prepare the spindle end of the prior art steering knuckle for mounting and attaching to a separate brake chassis increases the overall cost and complexity of manufacturing prior art steering knuckles.

[0012] Furthermore, when the spindle end is fabricated using this complex manufacturing process and attached to the prior art steering knuckle, four welds are typically required. The first weld is located between the center tube and the spindle during spindle end fabrication. The second weld is located between the inner end of the spindle end and the body of the prior art steering knuckle. The third and fourth welds attach the outer and inner sides of the brake chassis to the spindle end. Because the prior art steering knuckle requires four welds to attach the spindle end and the brake chassis, the overall strength of the spindle end is reduced. This increases the stress and fatigue on the spindle and may potentially lead to a reduced lifespan of the spindle end, and therefore, a potentially reduced lifespan of the prior art steering knuckle.

[0013] Furthermore, with this prior art steering knuckle, the overall length of the spindle end must be undesirably increased to support the attachment of the brake chassis, providing space for the welding torch to enter and attach the brake chassis to the spindle end. This increased length at the axle end results in the wheel hub and attached wheel being positioned further out of the pivot connection between the steering knuckle and the end component of the steerable axle via the kingpin. This increases stress and fatigue on the steering knuckle and the pivot connection between the steering knuckle and the end component, potentially leading to reduced life or premature failure of the pivot connection between the steering knuckle and / or the end component of the steerable axle.

[0014] Furthermore, such prior art steering knuckles typically include a tie rod arm welded to the knuckle body. This welded connection between the tie rod arm and the knuckle body can potentially fail when operating in harsh or severe environments, such as during off-road operation of heavy vehicles with self-steering axles / suspension systems (e.g., on construction sites), or during overload conditions on the steering knuckle. Alternatively, such prior art steering knuckles employ a pair of axial bolts configured to pass through corresponding aligned axial openings formed in the tie rod arm and the steering knuckle body to secure the tie rod arm to the body. This attachment configuration typically requires a relatively large steering knuckle body and / or a large tie rod arm to support this installation, resulting in an increase in the overall weight of the self-steering axle / suspension system, and thus an increase in the overall weight of heavy vehicles. Furthermore, due to packaging constraints, this configuration also undesirably limits the steering angle of the steering knuckle, and therefore the steering angle of the associated wheels.

[0015] Therefore, there is a need in the art for a steering knuckle for a self-steering axle / suspension system of heavy-duty vehicles, the steering knuckle comprising an integrally formed structure for mounting components of a drum braking system, which eliminates the complex manufacturing processes and components required for preparing a main shaft end of the steering knuckle capable of mounting a separate brake chassis to position and attach the separate brake chassis to the main shaft end, thereby reducing manufacturing complexity and cost. There is also a need in the art for a steering knuckle comprising a main shaft that is forged, machined, and then directly friction-welded to the steering knuckle using only a single friction weld joint, which eliminates the need for attaching the main shaft to the steering knuckle using multiple weld joints and for attaching a separate brake chassis to the main shaft of the steering knuckle using multiple weld joints, thereby reducing manufacturing cost and increasing the overall strength of the main shaft. There is also a need in the art for a steering knuckle that minimizes the distance from the kingpin to the bearing shoulder of the main shaft, and thus minimizes the distance from the kingpin to the vertical centerline of the wheel (attached to the hub, which is rotatably mounted on a bearing attached to the main shaft). This reduces stress on the steering knuckle and on the pivot connection between the steering knuckle and the end component of the steerable axle, thereby increasing the overall strength of the steering knuckle and reducing fatigue at the pivot connection between the steering knuckle and the steerable axle, and reducing the risk of potential premature failure of the steering knuckle and / or the pivot connection between the steering knuckle and the steerable axle. Furthermore, there is also a need in the art for a steering knuckle comprising separate tie rod arms connected to the steering knuckle in a manner that minimizes the overall size and weight of the steering knuckle while providing a robust structure to resist overload conditions, reducing the overall weight of heavy vehicles, providing the desired steering angle for the steering knuckle and the mounted wheel, and providing a robust structure for the steering knuckle to be used on self-steering axle / suspension systems with different components and constructions.

[0016] The steering knuckle for a self-steering axle / suspension system of heavy vehicles disclosed herein meets these requirements and overcomes the aforementioned disadvantages, defects and limitations, and will now be described. Summary of the Invention

[0017] The purpose of this disclosure is to provide a steering knuckle for a self-steering axle / suspension system of heavy-duty vehicles, which eliminates the complex manufacturing processes and components required for preparing the spindle end of the steering knuckle to enable mounting of a separate brake chassis and for machining multiple joints on the spindle end to position and attach the separate brake chassis, thereby reducing manufacturing complexity and cost.

[0018] Another object of this disclosure is to provide a steering knuckle for a self-steering axle / suspension system of heavy-duty vehicles, the steering knuckle having a construction / structure that eliminates the need to attach the main shaft to the steering knuckle using multiple welds, thereby reducing manufacturing costs and increasing the overall strength of the main shaft.

[0019] Another object of this disclosure is to provide a steering knuckle for a self-steering axle / suspension system of heavy vehicles, the steering knuckle minimizing the distance from the kingpin to the bearing shoulder of the main shaft, and thus minimizing the distance from the kingpin to the vertical centerline of the wheel (attached to the hub, which is rotatably mounted on a bearing attached to the main shaft), thereby reducing stress on the steering knuckle and stress on the pivot connection of the steering knuckle to the steerable axle of the self-steering axle / suspension system, increasing overall strength, and reducing fatigue of the steering knuckle and the pivot connection of the steering knuckle to the steerable axle, and reducing the risk of potential premature failure of the steering knuckle and / or the pivot connection of the steering knuckle to the steerable axle.

[0020] Another object of this disclosure is to provide a steering knuckle for a self-steering axle / suspension system for heavy vehicles, the steering knuckle comprising separate tie rod arms connected to the steering knuckle in such a way that the overall size and weight of the steering knuckle are minimized, while providing a robust structure to resist overload conditions and reducing the overall weight of the heavy vehicle, providing the desired steering angle for the steering knuckle and the mounted wheel, and providing a robust structure for the steering knuckle to be used on self-steering axle / suspension systems with different components and constructions.

[0021] These and other objectives are achieved by a steering knuckle for a self-steering axle / suspension system for heavy-duty vehicles, the steering knuckle comprising: a body receiving a kingpin of the self-steering axle / suspension system for pivotally connecting the steering knuckle to the axle of the self-steering axle / suspension system; a spindle extending from an outer surface of the body; and a drum brake system component mounting structure integrally formed with the body and mounting one or more components of the drum brake system. Attached Figure Description

[0022] Exemplary embodiments of this disclosure are set forth in the following description and illustrated in the accompanying drawings, which illustrate the best mode of application principles that the applicant has considered.

[0023] Figure 1 is a perspective view of a trailing arm heavy vehicle self-steering axle / suspension system employing a pair of prior art steering knuckles, showing the separate brake chassis of the drum brake assembly of the drum brake system, which is attached to the spindle end of each steering knuckle.

[0024] Figure 2 This is a perspective view of the steering knuckle of an exemplary embodiment of the self-steering axle / suspension system for heavy vehicles of the present disclosure, viewed in an inward direction, showing components of a drum brake assembly of a drum brake system, the components being mounted to a structure integrated into the steering knuckle.

[0025] Figure 3 This is a perspective view of an exemplary embodiment of a steering knuckle, viewed in an outward direction, the steering knuckle having Figure 2 The components of the installed drum brake assembly are shown.

[0026] Figure 4 yes Figure 2 An exploded perspective view of the steering knuckle of the exemplary embodiment shown illustrates the main shaft of the steering knuckle removed from the steering knuckle;

[0027] Figure 5 yes Figure 2 An exploded perspective view of the steering knuckle of the exemplary embodiment shown illustrates the tie rod arm of the steering knuckle removed from the steering knuckle and the associated mounting bolts;

[0028] Figure 6 yes Figure 2 The perspective view of the steering knuckle of the exemplary embodiment shown illustrates the orientation of the axle end component of the steerable axle of the self-steering axle / suspension system relative to the steering knuckle.

[0029] In all the accompanying drawings, similar numbers and characters represent similar parts. Detailed Implementation

[0030] To better understand the steering knuckles for heavy-duty vehicle self-steering axle / suspension systems of this disclosure and the environment in which they operate, a heavy-duty vehicle self-steering axle / suspension system employing a pair of prior art steering knuckles is shown in Figure 1, and is generally indicated by reference numeral 10.

[0031] The self-steering axle / suspension system 10 includes a steerable axle 20. The steerable axle 20 includes a center axle tube 34 supported by a pair of laterally spaced trailing arm beams 40, the center axle tube being welded or otherwise rigidly attached to the trailing arm beams. Each trailing arm beam 40 is pivotally attached at its front end to a corresponding one of a pair of laterally spaced frame hangers 42, the pair of laterally spaced frame hangers being rigidly attached to and suspended from a corresponding main member (not shown) of a heavy-duty vehicle frame. The self-steering axle / suspension system 10 includes a pair of air springs 46. Each air spring 46 extends between the rear end of the corresponding beam 40 and a corresponding main member of the heavy-duty vehicle frame, and is mounted on the rear end of the corresponding beam, which is also attached to the corresponding main member of the heavy-duty vehicle frame. The self-steering axle / suspension system 10 also includes a pair of shock absorbers 44. Each shock absorber 44 extends between a corresponding beam in the beam 40 and a corresponding hanger 42 and is mounted on the corresponding beam in the beam and the corresponding hanger. As is well known, during operation, the air spring 46 and the shock absorber 44 together help to provide the desired driving characteristics for the self-steering axle / suspension system 10, and thus provide the desired driving characteristics for heavy vehicles.

[0032] The steerable axle 20 also includes a pair of end members 54, which are attached to the respective outer ends of the center axle tube 34 of the steerable axle by any suitable means (e.g., welding). As will be described below, each end member 54 enables a pivotally connected prior art steering knuckle 58. Since prior art steering knuckles 58 are similar, for the sake of brevity and clarity, only a single prior art steering knuckle and its pivotal connection to the corresponding end member 54 of the steerable axle 20 will be described.

[0033] The prior art steering knuckle 58 includes a body 67 and a pair of arms 62 (only one shown) extending forward / inward from the body. The arms 62 of the steering knuckle 58 are vertically aligned with each other, such that there is a gap (not shown) between the arms. The arms 62 form corresponding vertical openings 59 (only one shown) that are vertically aligned with each other. The end member 54 of the steerable axle 20 also forms a vertical opening (not shown) and is disposed in the gap between the arms 62 of the steering knuckle 58, such that the opening is vertically aligned with the vertical openings 59 of the arms. A kingpin 56 is configured to pass through the aligned vertical openings 59 of the arms 62 of the steering knuckle 58 and the vertical openings of the end member 54 of the steerable axle 20 to pivotally attach the steering knuckle to the end member.

[0034] The prior art steering knuckle 58 includes a spindle end 68, which is rigidly attached to the outer surface of the steering knuckle by suitable means (e.g., welds or fasteners). A wheel end assembly (not shown) is rotatably mounted on the spindle end 68 in a manner known in the art. More specifically, the wheel end assembly includes a bearing assembly (not shown) having an inner bearing (not shown) and an outer bearing (not shown) mounted on the outer end of the spindle end 68. A spindle nut assembly (not shown) is threaded onto the outer end of the spindle end 68 and secures the inner and outer bearings in place. It is known that the wheel hub (not shown) of the wheel end assembly (not shown) is mounted on the inner and outer bearings for rotation relative to the spindle end 68. A hub cap (not shown) is mounted on the outer end of the hub and closes the outer end of the hub, thus closing the outer end of the wheel end assembly. A single rim (not shown) or a pair of rims (not shown) (depending on the specific design considerations of the wheel end assembly) is mounted to the hub using multiple threaded fasteners or studs (not shown) and mating nuts (not shown). As is well known, tires (not shown) are mounted on individual rims.

[0035] The prior art steering knuckle 58 includes a tie rod or pivot arm 60, which is rigidly attached to the steering knuckle body 67 by suitable means (e.g., a weld). The tie rod arm 60 forms a pair of longitudinally spaced openings (not shown). A tie rod 66 is pivotally connected to the rearmost opening of the pair of openings by a fastener 61 (only one shown). A coil-wrapped spring 64 is connected to the frontmost opening of the tie rod arm 60 by a fastener 63. The coil-wrapped spring 64 is in turn connected to a bracket 65, which is attached to the center axle tube 34 of the steerable axle 20 by any suitable means (e.g., a weld and / or a fastener). It is known that the coil-wrapped spring 64 helps to return the wheels attached to the self-steering axle / suspension system 10 to a straight direction after the vehicle has turned.

[0036] When a wheel mounted on a prior art steering knuckle 58 turns, the steering knuckle pivots about the kingpin 56 relative to the end member 54 of the steerable axle 20. When a heavy vehicle turns left forward, the wheels turn toward the driver's side of the vehicle, and the driver's side steering knuckle 58 pivots toward the end member 54 about the pivot joint via the kingpin 56, while the passenger side steering knuckle pivots away from its corresponding end member about the pivot joint via the corresponding kingpin. Conversely, when a heavy vehicle turns right forward, the wheels turn toward the passenger's side of the vehicle, and the passenger side steering knuckle 58 pivots toward its corresponding end member 54 about the pivot joint via the kingpin 56, while the driver's side steering knuckle pivots away from its corresponding end member about the pivot joint via the corresponding kingpin. Since the driver's side steering knuckle and the passenger side steering knuckle 58 are connected to each other by a tie rod 66, the corresponding wheels mounted on the steering knuckles remain substantially parallel to each other when the heavy vehicle turns left or right, wherein when turning left, the driver's side wheel turns at an angle slightly greater than that of the passenger side wheel, and when turning right, the passenger side wheel turns at an angle slightly greater than that of the driver's side wheel.

[0037] The self-steering axle / suspension system 10 incorporates components of the drum braking system 70 to provide braking for heavy vehicles. The drum braking system 70 includes a pair of drum brake assemblies 72, which are integrated into the respective outer ends of the self-steering axle / suspension system 10, as will be described in detail below. Since the drum brake assemblies 72 are similar, for the sake of brevity and clarity, only a single drum brake assembly will be described.

[0038] The drum brake assembly 72 includes a separate brake chassis 80, which is disposed on the spindle end 68 of a prior art steering knuckle 58 via a central hole 82 formed in the brake chassis, and is immovably attached to the spindle end by suitable means (e.g., a weld). The drum brake assembly 72 includes a camshaft assembly 74 mounted to the prior art steering knuckle 58 and the brake chassis 80. More specifically, the camshaft assembly 74 includes a cam tube 76. The outer end of the cam tube 76 is configured to pass through a cam tube hole 85 formed in the brake chassis 80, and is attached to the brake chassis by any suitable means (e.g., a weld). The inner end of the cam tube 76 extends inward from the cam tube hole 85 of the brake chassis 80, and can be attached to the body 67 of the steering knuckle 58 or the brake chassis 80 by suitable means (e.g., a weld).

[0039] The camshaft assembly 74 also includes a camshaft (not shown) configured to pass through and be rotatably mounted within a cam tube 76. More specifically, the camshaft passes through an outer bushing and an inner bushing (not shown) that are frictionally engaged within an outer end and an inner end of the cam tube 76, respectively. The camshaft extends outward and inward from the outer and inner ends of the cam tube 76, respectively. The outer and inner bushings within the cam tube 76 allow the camshaft to rotate within the cam tube. The camshaft includes a splined inner end (not shown) that extends inward from the inner end of the cam tube 76. As is known in the art, the splined inner end of the camshaft engages a corresponding splined inner surface (not shown) of a clearance adjuster (not shown). The camshaft assembly 74 also includes an S-shaped cam 78 attached to the outer end of the camshaft such that the S-shaped cam protrudes and is located outside and adjacent to the outer end of the cam tube 76.

[0040] The drum brake assembly 72 also includes a brake chamber 88, which is in fluid communication with an air source located on the heavy vehicle via a pneumatic line (not shown). The brake chamber 88 is known to actuate other components of the drum brake assembly to provide braking to the heavy vehicle. The brake chamber 88 is mounted to a bracket (not shown) that can be rigidly attached to the inner end of the steering knuckle 58 or cam tube 76 in a known manner. A pushrod 89 (only one shown) slidably and operably connected to the brake chamber 88 extends rearward from the brake chamber and is pivotally connected to a clearance adjuster.

[0041] During heavy vehicle braking, air is introduced from an air source located on the vehicle into brake chamber 88 via a pneumatic line connecting the air source and the brake chamber. As the air pressure within brake chamber 88 increases, pushrod 89 is pushed rearward. Since pushrod 89 is pivotally connected to a clearance adjuster, and the camshaft is connected to the clearance adjuster via a spline connection and rotatably mounted within cam tube 76, the rearward movement of the pushrod causes the camshaft to rotate within the cam tube. This, in turn, causes the S-shaped cam 78, attached to the outer end of the camshaft, to rotate. This forces a pair of brake pads (not shown) against the inner brake surface (not shown) of a brake drum (not shown) mounted to the wheel hub, thereby slowing or stopping the heavy vehicle. The pair of brake pads are pivotally connected to a pair of anchor pins (not shown) disposed within brake pad mounting openings 83 formed in the brake chassis 80.

[0042] While generally suitable for its intended purpose, the prior art steering knuckle 58 has certain disadvantages, defects, and limitations. As noted above, the steering knuckle 58 utilizes a brake chassis 80 (a separate component) to mount other components of the drum brake assembly 72, which is disposed on the spindle end 68 of the steering knuckle via a central hole 82 formed in the brake chassis and is immovably attached to the spindle end by suitable means (e.g., welding). To prepare the spindle end 68 to accommodate the mounting and attachment of the brake chassis 80, a relatively complex manufacturing process is typically employed. More specifically, to prepare the spindle end 68 to accommodate the mounting and attachment of the brake chassis 80, a pair of spindles (not shown) are first attached to a center tube (not shown) by friction welding to form a straight shaft (not shown). Then, a portion of the straight shaft, including a portion of the center tube and the friction-welded spindle portion, is cut from the straight shaft to provide the spindle end 68. The spindle end 68 is then welded or otherwise rigidly attached to the body 67 of the prior art steering knuckle 58. Then, the brake chassis 80 is typically mounted and welded to the spindle end 68 between the location where the inner wheel hub bearing is installed at the spindle end and the outer side of the body 67 of the prior art steering knuckle 58.

[0043] The relatively complex manufacturing process for preparing the main shaft end 68 for attaching to the body 67 of the steering knuckle 58 and subsequently mounting and attaching to the brake chassis 80 increases the total cost of manufacturing the steering knuckle 58, and thus increases the total cost of manufacturing the self-steering axle / suspension system 10. Furthermore, when attaching the main shaft end 68 to the steering knuckle 58 in this manner, four welds are required: the first weld is located between the center tube and the main shaft during the preparation of the main shaft end 68; the second weld is located between the inner end of the main shaft end and the body 67 of the steering knuckle 58; and the third and fourth welds attach the brake chassis 80 to the main shaft end 68, with the third weld located on the outer side of the brake chassis and the fourth weld located on the inner side of the brake chassis. Because four welds are required to attach the spindle end 68 to the body 67 of the steering knuckle 58 and to the brake chassis 80, the overall strength of the spindle end and the brake chassis attached to it may be potentially reduced. This increases stress and fatigue at the attachment points of the spindle end and the brake chassis, and may potentially lead to a reduced lifespan of the spindle end, and thus a reduced lifespan of the steering knuckle 58. Furthermore, due to the relatively limited space between the inner side of the brake chassis and the outer surface of the body 67 of the steering knuckle 58, and the interference of the cam tube 76 of the camshaft assembly 74, it is difficult to perform the fourth weld located on the inner side of the brake chassis 80. Moreover, the limited space and the interference of the cam tube 76 of the camshaft assembly 74 may require interruption of the fourth weld in the region of the cam tube, thus undesirably preventing the weld from fully circumferentially surrounding the inner surface of the spindle end 68 and the brake chassis 80 near the center hole 82 of the brake chassis.

[0044] Furthermore, to support the mounting and attachment of the brake chassis 80 to the spindle end 68, and thus to the prior art steering knuckle 58, the overall length of the spindle end must be undesirably increased to provide space for the welding torch to enter and attach the brake chassis to the spindle end. This increased length of the spindle end 68 results in the hub and attached wheel being positioned further out of the pivot connection of the steering knuckle 58 via the kingpin 56 to the end member 54 of the steerable axle 20. This increases stress and fatigue on the steering knuckle and the pivot connection to the end member. This could potentially lead to premature failure of the steering knuckle 58 and / or premature failure of the pivot connection to the end member 54 of the steerable axle 20 unless additional support structures are incorporated into the steering knuckle to compensate for the higher loads on the steering knuckle and the pivot connection to the steerable axle, which would undesirably increase the cost of the steering knuckle and the overall weight of the heavy vehicle.

[0045] Furthermore, in the prior art, the tie rod arm 60 of the steering knuckle 58 is welded to the body 67 of the steering knuckle. When operating in harsh environments, such as during off-road operation of a heavy vehicle coupled with a self-steering axle / suspension system 10 (e.g., on a construction site), or during overload conditions on the steering knuckle, the welded connection between the tie rod arm 60 and the body 67 of the steering knuckle 58 may potentially fail. The steering knuckle for a self-steering axle / suspension system for heavy vehicles disclosed herein overcomes the aforementioned disadvantages, defects, and limitations, and will now be described.

[0046] The steering knuckle of the exemplary embodiment of the self-steering axle / suspension system for heavy-duty vehicles disclosed herein is in... Figures 2-6 As shown, it is generally indicated by 200. The steering knuckle 200 of the exemplary embodiment is used in conjunction with a self-steering axle / suspension system for heavy vehicles (e.g., the self-steering axle / suspension system 10 described above). As will be described in detail below, a pair of steering knuckles 200 of the exemplary embodiment are pivotally connected to the steerable axle 120 of the self-steering axle / suspension system (…). Figure 6 The corresponding ends of the steering knuckle 200 are similar to those of the exemplary embodiment of the steering knuckle 200 which is pivotally connected to the corresponding ends of the steering axle 120. For the purposes of brevity and clarity, only one steering knuckle and the pivotal connection of the steering knuckle to the steering axle will be described in detail.

[0047] refer to Figures 2-6 The steering knuckle 200 of an exemplary embodiment includes a body or brake chassis portion 266 formed of a suitable rigid material (e.g., steel). The body 266 is preferably formed by forging, but depending on the material used, it may also be formed by other suitable methods (e.g., casting) without affecting the overall concept or operation of this disclosure. Reference Figure 3 and Figures 5-6The main body 266 has a first arm or lower arm 280. The first arm 280 extends inward from the main body 266 near the bottom of the main body. (Reference) Figures 3-6 The body 266 also has a second arm or upper arm 282. The second arm 282 extends inwardly from the body 266 adjacent to the top of the body and is spaced apart from and generally vertically or coaxially aligned with the first arm 280. The first arm 280 and the second arm 282 are preferably integrally formed as a single component with the body 266, for example, during a forging operation. (Reference) Figure 3 and Figures 5-6 The first arm 280 includes a receiving pin 260 ( Figure 6 The vertical opening 281 at the first end or lower part 261 of the ) . Reference Figures 3-6 The second arm 282 includes a vertical opening 283, which is vertically or coaxially aligned with the opening 281 of the first arm 280, for receiving the master pin 260. Figure 6 The second end or upper part 263. (See reference) Figure 3 Bushing 286a is disposed in opening 281 of first arm 280, and bushing 286b is disposed in opening 283 of second arm 282.

[0048] refer to Figures 3-6 In the exemplary embodiment, the body 266 of the steering knuckle 200 also forms a tie rod arm mounting structure 270. (See reference...) Figure 5 The tie rod arm mounting structure 270 is formed together with and extends substantially rearward from the first arm 280, and is formed together with and extends inwardly from the body 266 of the steering knuckle 200 of the exemplary embodiment. The mounting structure 270 includes a horizontally planar tie rod arm attachment surface 272. The attachment surface 272 includes a threaded vertical opening 273 extending vertically into the mounting structure 270, the importance of which will be described in detail below. The body 266 of the steering knuckle 200 has a vertically planar tie rod arm attachment surface 267 formed on its inner side. The attachment surface 267 includes a threaded axial opening 271 extending outwardly through the body 266. Figures 4-5 Its importance will be described in detail below.

[0049] refer to Figure 6The kingpin 260 is used to pivotally connect the steering knuckle 200 of the exemplary embodiment to the steerable axle 120 of the self-steering axle / suspension system (not shown). The steerable axle 120 is structurally and functionally similar to the steerable axle 20 described above, except that it employs a pair of end members 140 comprising a structure different from that of end member 54. Similar to the steerable axle 20, the steerable axle 120 includes a center axle tube (not shown) attached by any suitable means (e.g., welds and / or fasteners) to a pair of laterally spaced trailing arm beams (not shown) of the self-steering axle / suspension system, such as beam 40 of the self-steering axle / suspension system 10 described above. Each end member 140 is attached to a corresponding outer end of the center axle tube of the steerable axle 120, which will be described in detail below. Since the end members 140 are similar, for the sake of brevity and clarity, only one end member will be described in detail.

[0050] Continue to refer to Figure 6 The end member 140 of the steerable axle 120 is forged from a suitable robust material (e.g., steel) and then machined. The end member 140 includes a main portion 142 having a vertical opening 144 extending fully through it for receiving a central portion (not shown) of a kingpin 260. The end member 140 includes an axle attachment portion or plug portion 146 extending inwardly from the main portion 142 such that the axial central axis A of the end member extends in a direction axial to the vertical or coaxial central axis C of the opening 144. The axle attachment portion 146 of the end member 140 has an outer periphery shaped and sized to press-fit within the end of the central axle tube of the steerable axle 120. In the example shown, the axle attachment portion 146 has a generally cylindrical construction and a solid structure. However, depending on the shape and construction of the center axle tube of the steerable axle 120, the axle attachment portion may also have different constructions and / or structures (e.g., square constructions and / or hollow structures) without affecting the overall concept or operation of this disclosure. The center axle tube may have surface devices, such as one or more windows (not shown), near the end of the center axle tube for welding the end member 140 to the center axle tube of the steerable axle 120 to prevent relative rotation. It is conceivable that, depending on the construction and / or structure of the end member 140 and / or the steerable axle 120, the end member may be attached to the axle center tube of the steerable axle by means other than an interference fit (e.g., by friction welding) without affecting the overall concept or operation of this disclosure.

[0051] The main portion 142 of the end member 140 is disposed in the gap between the vertically or coaxially spaced first arm 280 and second arm 282 of the steering knuckle 200 in the exemplary embodiment, such that when the main portion of the end member is positioned between the first and second arms, the vertical opening 144 is vertically or coaxially aligned with the openings 281 and 283 of the first and second arms, respectively. The kingpin 260 is configured to pass through the opening 283 of the vertically or coaxially aligned second arm 282 of the steering knuckle 200, the opening 144 of the end member 140 of the steerable axle 120, and the opening 281 of the first arm 280 of the steering knuckle. The kingpin 260 is immovable relative to the main portion 142 of the end member 140 of the steerable axle 120 by a draw key (not shown), which engages in the central portion of the kingpin a corresponding flat portion (not shown) that can be machined inside the kingpin. A tapered key is wedged around the opening 144 between a corresponding flat portion machined inside the kingpin and the end member 140 of the steerable axle 120, thereby forcing the kingpin into contact with the outside of the opening to immovably secure the kingpin to the end member. Alternatively, the kingpin 260 may be immovable relative to the main portion 142 of the end member 140 of the steerable axle 120 by more than one tapered key. For example, the kingpin 260 may be immovable relative to the main portion 142 of the end member 140 of the steerable axle 120 by a pair of tapered keys (not shown), each tapered key engaging a corresponding flat portion (not shown) machined inside the bottom and outside the top of the kingpin in the central portion of the kingpin. In this configuration, a tapered sliding key is wedged around opening 144 between corresponding flat portions machined on the top outer side and bottom inner side of the kingpin 260 and the end member 140 of the steerable axle 260, forcing the kingpin to contact the inside of the opening near the top and the outside of the opening near the bottom, thus immovably securing the kingpin to the end member. Once positioned within the vertically or coaxially aligned opening 283 of the second arm 282 of the steering knuckle 200, immovably secured within the opening 144 of the end member 140 of the steerable axle 120, and positioned within the opening 281 of the first arm 280 of the steering knuckle, the kingpin 260 is substantially along the vertical central axis C ( Figure 6 ) extends, and is therefore substantially perpendicular to the axial central axis A of the end member 140. Figure 6 And thus substantially perpendicular to the steerable axle 120. In this way, the steering knuckle 200 of the exemplary embodiment is pivotally mounted around the kingpin 260 in both the forward and rearward directions.

[0052] A cap (not shown) is provided in a countersunk hole 284 formed in the second arm 282 of the steering knuckle 200 in an exemplary embodiment adjacent to the opening 283. Figures 3-6The cap is sealed inside and at the upper end of the opening to prevent contaminants from the heavy vehicle operating environment from entering the pivot connection between the steering knuckle and the end member 140 of the steerable axle 120 via the kingpin 260. The upper surface or outermost surface (not shown) of the cap can be connected to the upper surface 285 of the second arm 282. Figures 3-6 The end members 140 of the steering knuckle 200 and the steerable axle 120 of the exemplary embodiment are preferably manufactured in a complementary manner to support the kingpin 260 in a substantially vertical orientation; however, they may also be manufactured such that they have a relatively small total negative camber angle in the range of about 0.5 degrees (0.5°) to about 5.0 degrees (5.0°) without affecting the overall concept or operation of this disclosure.

[0053] refer to Figures 2-6 An exemplary embodiment of the steering knuckle 200 includes a spindle 264, which is fixed to the body 266 of the steering knuckle by any suitable means (e.g., welding). More specifically, the body 266 includes a portion having an outer end 269 ( Figure 4 The protrusion 268 of the main shaft 264 is sized such that it has the same dimensions as the inner end 265 of the main shaft 264. Figure 2 and Figures 4-6 The inner and outer diameters of the main shaft 264 are substantially the same as those of the corresponding inner and outer diameters of the main shaft 264. The main shaft 264 is preferably friction-welded to the body 266 of the steering knuckle 200 at the joint between the inner end 265 of the main shaft and the outer end 269 of the protrusion 268 of the body. The protrusion 268 allows the welded portion (not shown) of the friction welding process to have a good shape and relatively uniform weld curls (not shown) on the protrusion and on the main shaft 264. The weld curls at the welded portions located on the inner end 265 of the main shaft 264 and the outer periphery of the protrusion 268 can be machined away. The weld curls at the welded portions located on the inner periphery do not interfere with operation or affect the strength and life of the main shaft 264, and therefore do not affect the strength and life of the steering knuckle 200, and can be left in place. The spindle 264 is forged from a suitable material (e.g., steel) and then machined to have precise dimensions, such as those for mounting wheel end assemblies, before being friction-welded to the protrusion 268 of the body 266 of the steering knuckle 200.

[0054] The spindle 264 is oriented relative to the kingpin 260 such that the steering knuckle 200 of the exemplary embodiment provides a forward kingpin arrangement for the self-steering axle / suspension. That is, the vertical centerline C through which the kingpin 260 extends... Figure 6 The axial center axis B of the main spindle 264 is located at the axis. Figures 2-6The kingpin 260 extends through a vertical centerline C that is preferably positioned 1.5 inches to 5 inches in front of the axial centerline B, but may also be positioned at other distances in front of the axial centerline without affecting the overall concept or operation of this disclosure.

[0055] The main shaft 264 enables the mounting of wheel-end assemblies (not shown) for a self-steering axle / suspension system. More specifically, the wheel-end assembly includes a bearing assembly (not shown) having an inner bearing (not shown) and an outer bearing (not shown) mounted on the outer end of the main shaft 264. Reference Figure 2 and Figures 4-6 The inner bearing abuts against the outer end 278 of the bearing shoulder 276 formed on the main shaft 264. On the main shaft 264, the outer bearing is spaced outward from the inner bearing. A main shaft nut assembly (not shown) is threaded onto the outer end of the main shaft 264 and secures the inner and outer bearings in place. The hub (not shown) of the wheel end assembly is mounted on the inner and outer bearings for rotation relative to the main shaft 264. A hub cap (not shown) is mounted on the outer end of the hub and closes the outer end of the hub, thus closing the outer end of the wheel end assembly. A single rim (not shown) or a pair of rims (not shown) (depending on the specific design considerations of the wheel end assembly) is mounted to the hub using multiple threaded fasteners or studs (not shown) and mating nuts (not shown). Tires (not shown) are mounted on the respective rims. It should be understood that the main shaft 264 may have other shapes and configurations than those shown and described without affecting the overall concept or operation of this disclosure.

[0056] refer to Figure 6 When the self-steering axle / suspension system positions the vehicle tires in a straight forward position or under load without steering, the axial center axis B of the main shaft 264 ( Figures 4-6 The spindle 264 is substantially axially aligned with the axial center axis A of the steerable axle 120. The spindle 264 can pivot about 30° in either direction from the straight forward position of the wheel about the kingpin 260 relative to the axial center axis A of the steerable axle 120.

[0057] refer to Figures 2-6 The steering knuckle 200 of the exemplary embodiment includes a separate tie rod arm 290 for attaching a tie rod (not shown) to a self-steering axle / suspension system, such as the tie rod 66 of the self-steering axle / suspension system 10 described above. The tie rod arm 290 includes a body portion 292 ( Figures 3-6 The main body portion 292 has an axially extending opening (not shown) that passes through the main body; its importance will be described below. (Reference) Figure 3 and Figures 5-6 The lever arm 290 also includes a mounting arm 296, which is integrally formed with and extends forward from the main body portion 292. The mounting arm 296 has a vertical opening (not shown), the significance of which will also be described below. Reference Figures 2-6 The lever arm 290 also includes a rearwardly extending lever attachment portion 294. A vertical opening 295 is formed in the lever attachment portion 294 adjacent to the rear end of the lever attachment portion.

[0058] refer to Figures 3-6 The tie rod arm 290 is positioned relative to the body 266 of the steering knuckle 200 in the exemplary embodiment such that the outer surface of the body portion 292 of the tie rod arm contacts the tie rod arm attachment surface 267 of the body. Figure 5 And flush with it, and the mounting arm of the lever arm 296 ( Figure 3 and Figures 5-6 The bottom surface of the tie rod arm mounting structure 270 contacts the main body. Figures 3-6 ) tie rod arm attachment surface 272 ( Figure 5 And flush with it. When the tie rod arm 290 is positioned relative to the body 266 in this manner, the axially extending opening formed in the body portion 292 of the tie rod arm and the attachment surface 267 formed in the body of the steering knuckle 200 are flush with it. Figure 5 271 with threaded axial opening in ) Figures 4-5 Axially aligned and formed on the mounting arm 296 of the tie rod arm. Figure 3 and Figures 5-6 The vertical opening in the steering knuckle and the attachment surface 272 formed in the mounting structure 270 of the steering knuckle Figure 5 The threaded vertical opening 273 in ) Figure 5 Align vertically.

[0059] refer to Figures 3-6 The first bolt or axial bolt 297 is configured to pass through the tie rod arm 290 ( Figures 2-6 An axially extending opening in the main body portion 292 of the steering knuckle 200, and a threaded engagement formed on the tie rod arm attachment surface 267 of the main body 266 of the steering knuckle 200. Figure 5 The aligned axial opening 271 in ) Figures 4-5 ). refer to Figure 3 and Figures 5-6 The second bolt or radial bolt 299 is configured to pass through a vertical opening formed in the mounting arm 296 of the tie rod arm 290, and is threadedly engaged in the mounting structure 270 of the steering knuckle 200. Figures 3-6 ) tie rod arm attachment surface 272 ( Figure 5The vertical opening 273 is aligned in the steering knuckle 200 of the exemplary embodiment. Thus, the tie rod arm 290 is removably fixed to the body 266 of the steering knuckle 200. The tie rod arm 290 supports the pivot attachment of the tie rod (not shown) such that when the wheel is in the straight-forward position, the axial central axis (not shown) of the tie rod is positioned parallel to the steerable axle 120. Figure 6 The axial center axis A of ).

[0060] The steering knuckle 200 of the exemplary embodiment also includes a structure that houses components of the tire inflation system and, for example, vents the interior of the wheel end assembly mounted on the main shaft 264 during periods of pressure buildup within the wheel end assembly due to leakage from the tire inflation system components. More specifically, refer to... Figure 3 and Figures 5-6 The main body 266 of the steering knuckle 200 has a first axial opening 230, which is positioned on the protrusion 268. Figure 4 The first axial opening extends through the body at a position on the radially inner side of the main shaft 264, such that when the main shaft 264 is attached to the protrusion, the first axial opening is adjacent to the interior 274 of the main shaft. Figure 2 and Figure 4 Fluid communication. The first axial opening 230 is sized such that pneumatic lines of a tire inflation system (not shown) of a type known in the art can pass through this opening and extend from the outside of the steering knuckle 200 to the inside 274 of the main shaft 264. Figure 2 and Figure 4 This extends into other components (not shown) (e.g., wheel valves and rotary joints) of the tire inflation system incorporated into the wheel end assembly to support the inflation of the tires of the wheels rotatably mounted on the axle via the hub.

[0061] refer to Figure 3 An exemplary embodiment of the steering knuckle 200 includes an exhaust system 240 incorporated therein. (Reference) Figures 4-6 The exhaust system 240 includes an axial opening 244, which is positioned at the protrusion 268. Figure 4 The spindle 264 extends through the body 266 of the steering knuckle 200 at a position on the radially inner side, such that when the spindle 264 is attached to the protrusion, the axial opening is adjacent to the interior 274 of the spindle. Figure 2 and Figure 4 Fluid connectivity. (Reference) Figure 3 The pneumatic check valve 246 of the exhaust system 240 is attached to an axial opening 244 on the inner surface of the body 266 of the steering knuckle 200. The exhaust pipe 248 is connected to the check valve 246 via a hose clamp 249.

[0062] When, for example, a leak in a tire inflation system component causes pressure buildup in the wheel end assembly mounted on the spindle 264 of the steering knuckle 200 in the exemplary embodiment, the steering knuckle's venting system 240 allows pressurized air to be expelled from the interior of the wheel end assembly to the atmosphere. More specifically, pressurized air from within the wheel end assembly can flow from the interior of the wheel end assembly through the interior 274 of the spindle 264. Figure 2 and Figure 4 The exhaust system 240 includes an axial opening 244, a check valve 246, and an exhaust pipe 248, and flows to the atmosphere. It is conceivable that the steering knuckle 200 of the exemplary embodiment could employ an exhaust system 240 in a self-steering axle / suspension system configuration that does not use a tire inflation system. In this configuration, since the pneumatic lines do not pass through the first axial opening 230 formed in the body 266 of the steering knuckle 200, the first axial opening can be plugged by a suitable means. Thus, the exhaust system 240 of the steering knuckle 200 prevents pressure build-up within the components of the wheel end assembly mounted on the main shaft 264 and reduces the possibility of damage to components (e.g., associated seals (not shown) and bearings (not shown)) due to such pressure build-up.

[0063] According to an important aspect of this disclosure, the steering knuckle 200 of an exemplary embodiment includes a structure of components integrated into the steering knuckle for mounting a drum brake assembly 302 of a drum brake system 300. More specifically, refer to Figures 2-6 The body or brake chassis portion 266 of the steering knuckle 200 has a pair of brake shoe mounting openings 277 near the top of the body. The brake shoe openings 277 allow for the pivotal mounting of the upper brake shoe 304A and the lower brake shoe 304B. Figures 2-3 More specifically, see reference. Figures 2-3Anchor pins 308 are disposed within each of the openings 277 and extend through the opening. Each anchor pin 308 is slidably fitted within a corresponding bushing (not shown) disposed within the corresponding brake shoe opening 277. Brake shoes 304A and 304B each include a corresponding pair of sidewalls 305A and 305B rotatably connected to the corresponding anchor pins in the anchor pins 308 in a manner known in the art. Each brake shoe 304A and 304B includes brake shoe tables 306A and 306B, respectively, which are rigidly attached to the corresponding sidewalls 305A and 305B by suitable means (e.g., welded joints). Each brake shoe 304A and 304B also includes a corresponding pair of brake pads 307A and 307B, which are attached to the corresponding brake shoe tables 306A and 306B by a corresponding plurality of fasteners 309A and 309B (e.g., rivets). It should be understood that the main body of the steering knuckle 200 or the brake chassis portion 266 may only have a single brake shoe mounting opening 277 adjacent to the top of the main body, in which the anchoring pin 308 is disposed to support the single anchoring pin drum brake system configuration, without affecting the overall concept or operation of this disclosure. In this configuration, the anchoring pin 308 may be interference-fitted within the single brake shoe mounting opening 277 or slidably fitted within a bushing (not shown) disposed within the single brake shoe mounting opening.

[0064] refer to Figure 2 A first resilient retaining member (not shown) (preferably a helical tension spring, referred to in the art as a retaining spring) is connected near the pivot connection from the sidewall to the anchor pin 308 to a corresponding first opening 310A (only one shown) formed in the sidewall 305A of brake shoe 304A and a corresponding first opening 310B (only one shown) formed in the sidewall 305B of brake shoe 304B, respectively, and extends between the first openings. A second resilient retaining member (not shown) (also preferably a helical tension spring, referred to in the art as a return spring) is connected to a corresponding second opening 311A ​​formed in the sidewall 305A of brake shoe 304A and a second opening (not shown) formed in the sidewall 305B of brake shoe 304B, respectively, and extends between the second openings. The second resilient retaining member retains the ends of the sidewalls 305A and 305B of brake shoes 304A and 304B opposite to their pivot connection to the anchor pin 308 to the corresponding rollers 312A and 312B, respectively.

[0065] The steering knuckle 200 of the exemplary embodiment also includes a structure that enables the mounting of a cam support assembly 320 for a drum brake assembly 302. More specifically, refer to... Figure 2 and Figures 4-6The steering knuckle 200 has a cam tube opening 279 formed on its lower end adjacent to the body. The cam tube opening 279 extends axially through the body 266 and includes a tie rod arm mounting structure 270 passing through the body. The cam tube opening 279 is sized to accommodate a cam support assembly 320. Figures 2-3 The cam tube 322 is disposed within the opening. The cam tube 322 is rigidly attached to the body 266 within the cam tube opening 279 by any suitable means (e.g., a weld). The cam support assembly 320 includes a camshaft (not shown) disposed through the cam tube 322 and rotatably mounted within the cam tube. More specifically, the camshaft passes through an outer bushing and an inner bushing (not shown), which are frictionally engaged within the outer and inner ends of the cam tube 322, respectively, and extend outward and inward from the outer and inner ends of the cam tube, respectively. The outer and inner bushings within the cam tube 322 allow the camshaft to rotate within the cam tube. The camshaft includes a splined inner end (not shown) extending inward from the inner end of the cam tube 322. The splined inner end of the camshaft engages meshingly with a corresponding splined inner surface (not shown) of the clearance adjuster (not shown) of the drum brake assembly 302. The cam support assembly 320 also includes an S-shaped cam (not shown) attached to the outer end of the camshaft such that the S-shaped cam protrudes and is located outside and adjacent to the outer end of the cam tube 322, and operably engages rollers 312A and 312B in a manner known in the art. Figure 2 ).

[0066] refer to Figures 2-3 The brake chamber mounting bracket 326 is rigidly attached to the inner end of the cam tube 322 by any suitable means (e.g., welding). The brake chamber mounting bracket 326 has a pair of openings 327. Figure 3 The pair of openings allow for the installation of a brake chamber (not shown) of a type known in the art, operatively connected via pneumatic lines to an air source located on a heavy vehicle. A push rod (not shown) slidably and operatively connected to the brake chamber extends rearward from the brake chamber and passes through a notch 328 formed in a bracket. The rear end of the push rod is pivotally attached to a clearance adjuster in a known manner.

[0067] During heavy vehicle braking, in response to a braking command, pressurization of the brake chamber pushes the pushrod backward and causes the clearance adjuster to rotate at the splined connection between the clearance adjuster and the camshaft, which in turn rotates the camshaft within the cam tube 322 of the cam support assembly 320. This, in turn, engages the S-shaped cam with rollers 3312A and 312B. Rollers 312A and 312B then contact the corresponding sidewalls 305A and 305B of brake shoes 304A and 304B. The S-shaped cam causes each roller 312A and 312B to move in a generally radially outward direction, reacting on each corresponding anchor pin 308 and overcoming the forces of the first and second resilient retaining members connected to the corresponding sidewalls 305A and 305B of brake shoes 304A and 304B. When the forces of the first and second resilient retaining members are overcome, brake shoes 304A and 304B pivot about the anchor pin 308, causing the brake shoes to move radially outward. As brake shoes 304A and 304B move radially outward, their corresponding brake pads 307A and 307B contact the inner surface of the brake drum to decelerate or stop the heavy vehicle, which is attached to the hub of a wheel end assembly rotatably mounted on the spindle 264 of the steering knuckle 200 in the exemplary embodiment. It is well known that when braking is complete, a first resilient retaining member and a second resilient retaining member move each brake shoe 304A and 304B substantially radially inward to a non-application position.

[0068] Because the body 266 of the steering knuckle 200 of the exemplary embodiment allows the components of the drum brake assembly 302 of the drum brake system 300 (including brake shoes 304A and 304B and cam tube 322) to be directly mounted on the steering knuckle, the steering knuckle eliminates the need for a separate brake chassis (e.g., a brake chassis 80 attached to the spindle end 68 of a prior art steering knuckle 58) that needs to be rigidly attached to the spindle end to support the mounting of such drum brake assembly components. This, in turn, eliminates the relatively complex manufacturing process and additional components required to prepare the spindle end for mounting and attaching a separate brake chassis (e.g., the relatively complex manufacturing process and additional components required to mount and attach the separate brake chassis 80 to the spindle end 68 of a prior art steering knuckle 58), thus reducing the overall manufacturing complexity and cost of the steering knuckle 200 of the exemplary embodiment compared to prior art steering knuckles.

[0069] Furthermore, since the structure of the components for mounting the drum brake assembly 302 of the drum brake system 300 (including the brake shoe mounting opening 277 and the cam tube opening 279) is integrated into the body 266 of the steering knuckle 200, and the need to mount a separate brake chassis on the main shaft of the steering knuckle to mount the drum brake assembly is eliminated, the overall length of the main shaft 264 can be reduced compared to the prior art steering knuckle main shaft end (e.g., the main shaft end 68 of the prior art steering knuckle 58 to which the brake chassis 80 is mounted and attached) that requires mounting a separate brake chassis. Therefore, the steering knuckle 200 of the exemplary embodiment enables a reduction in the distance D between the outer end 278 of the bearing shoulder 276 and the vertical central axis C (along which the kingpin 260 extends) compared to the prior art. Figure 6 The distance D is preferably in the range of about 7.5 inches to about 10.5 inches, more preferably in the range of about 8.5 inches to about 9.5 inches. This, in turn, allows the wheel hub, rotatably mounted on the inner and outer bearings mounted on the main shaft 264, to be closer inward to the pivot connection of the steering knuckle 200 via the kingpin 260 to the end member 140 of the steerable axle 120, which shortens the vertical centerline (not shown) of the wheel connected to the wheel hub from the vertical center axis C compared to the prior art. Figure 6 The distance between the kingpin 260 extending along the vertical central axis and the vertical centerline C (along the vertical centerline of the brake shoe mounting opening 277, and thus the vertical centerline of brake shoes 304A and 304B) is reduced compared to prior art steering knuckles (e.g., prior art steering knuckle 58). Figure 6 The distance E is preferably in the range of about 4.0 inches to about 7.0 inches, more preferably in the range of about 4.5 inches to about 6.0 inches. This overall design with fewer cantilever arms reduces stress and fatigue on the steering knuckle 200 and on the pivoting connection between the steering knuckle and the end member 140 of the steerable axle 120, and thus reduces the likelihood of premature failure of the steering knuckle and / or the connection between the steering knuckle and the end member.

[0070] According to another important aspect of this disclosure, since the tie rod arm 290 is connected to the body 266 of the steering knuckle 200 of the exemplary embodiment via a first bolt 297 and a second bolt 299, the tie rod arm is removable from the steering knuckle, and therefore removable from the self-steering axle / suspension system. This enables the steering knuckle 200 of the exemplary embodiment to provide sufficient flexibility and stability during the assembly of a self-steering axle / suspension employing the steering knuckle of the exemplary embodiment, such that the steering knuckle can be incorporated into and used with self-steering axle / suspension systems having different components and configurations than those shown and described (e.g., assembled top-mounted self-steering axle / suspension systems).

[0071] Furthermore, the construction and manner in which the tie rod arm 290 connects to the body 266 of the steering knuckle 200 in the exemplary embodiment minimizes the overall required size of the steering knuckle while providing a robust structure to resist overload conditions. This reduces the overall weight of heavy vehicles, provides the desired steering angle for the steering knuckle and the mounted wheel, and provides the desired strength for the steering knuckle. More specifically, and particularly referring to... Figures 5-6 The second bolt 299 is configured to pass through a vertical opening formed in the mounting arm 296 of the tie rod arm 290 and threadedly engage with a threaded vertical opening 273 formed in the tie rod arm attachment surface 272 of the mounting structure 270. The first bolt 297 is configured to pass through an axially extending opening formed in the body portion 292 of the tie rod arm 290 and threadedly engage with an axial opening 271 formed in the tie rod arm attachment surface 267 of the body 266, such that the first bolt and the second bolt are positioned approximately 90 degrees (90°) apart from each other in the offset axial and vertical planes, respectively. Additionally, the first bolt 297 provides an axial connection between the tie rod arm and the body of the steering knuckle, and the first bolt is the attachment point of the tie rod arm 290 to the body 266 closest to the tie rod attachment portion 294 of the tie rod to the tie rod arm. This attachment configuration of the tie rod arm 290 to the body 266 provides a robust and secure connection with sufficient clamping force to resist overload conditions without tie rod arm failure or loosening of the tie rod to tie rod arm connection and / or tie rod arm to steering knuckle 200 body connection.

[0072] Furthermore, since the second bolt 299 is configured to pass through a vertical opening formed in the mounting arm 296 of the tie rod arm 290 and threadedly engage with a threaded vertical opening 273 formed in the tie rod arm attachment surface 272 of the mounting structure 270, there is sufficient clearance to allow the steering knuckle 200 of the exemplary embodiment to provide a wheel cut of up to thirty degrees (30°) for the wheel associated with the steering knuckle, and to accommodate mounting and provide clearance for the cam tube 322 of the cam support assembly 320, which is disposed within a cam tube opening 279 formed in the body 266 of the steering knuckle 200.

[0073] Therefore, the steering knuckle of the exemplary embodiment of the self-steering axle / suspension system 200 disclosed herein includes an integrally formed structure for mounting components of a drum braking system. This eliminates the complex manufacturing process of preparing the spindle end of the steering knuckle capable of mounting a separate brake chassis and machining multiple joints on the spindle end to position and attach the separate brake chassis, thereby reducing manufacturing complexity and cost. The steering knuckle 200 of the exemplary embodiment includes a spindle that is forged, machined, and then directly friction-welded to the steering knuckle using only a single friction weld joint. This eliminates the need to attach the spindle to the steering knuckle and the brake chassis to the spindle using multiple weld joints, thereby reducing manufacturing costs and increasing the overall strength of the spindle. Furthermore, by integrating the structure for mounting the drum brake system components into the steering knuckle 200 of the exemplary embodiment, the distance from the brake chassis to the kingpin is minimized, thus minimizing the distance from the bearing shoulder of the main shaft to the kingpin, and consequently minimizing the distance from the kingpin to the vertical centerline of the wheel mounted on the main shaft. This reduces the stress on the steering knuckle and the stress on the pivot connection between the steering knuckle and the end component of the steerable axle, thereby increasing the overall strength of the steering knuckle and reducing fatigue of the steering knuckle and the pivot connection between the steering knuckle and the steerable axle, and reducing the risk of potential premature failure of the steering knuckle and / or the pivot connection between the steering knuckle and the steerable axle. Furthermore, the steering knuckle 200 of the exemplary embodiment includes separate tie rod arms bolted to the steering knuckle via axial and radial bolt connections in a manner that minimizes the overall size and weight of the steering knuckle, while providing a robust structure to resist overload conditions. This reduces the overall weight of heavy vehicles, provides the desired steering angle for the steering knuckle and the mounted wheels, and provides a robust structure for the steering knuckle to be used on self-steering axle / suspension systems with different components and constructions.

[0074] It should be understood that the steering knuckle of this disclosure for a self-steering axle / suspension system for heavy-duty vehicles can be applied to all types of self-steering axle / suspension systems known to those skilled in the art, including self-steering axle / suspension systems having components and constructions other than those shown and described herein, without affecting the concept or operation of this disclosure. It should also be understood that the steering knuckle of this disclosure for a self-steering axle / suspension system for heavy-duty vehicles can include shapes and constructions other than those shown and described, without affecting the overall concept or operation of this disclosure. Furthermore, it should be understood that the steering knuckle of this disclosure for a self-steering axle / suspension system for heavy-duty vehicles can be used in conjunction with drum braking systems (e.g., drum braking systems including a single anchor pin construction) having components and constructions different from those shown and described, without affecting the concept or operation of this disclosure.

[0075] Therefore, the steering knuckle for self-steering axle / suspension systems of heavy vehicles disclosed herein is simplified, providing an effective, safe, inexpensive and efficient structure for achieving all the listed objectives, eliminating the difficulties encountered by prior art steering knuckles for self-steering axle / suspension systems of heavy vehicles, and solving problems in the prior art and achieving new results.

[0076] In the above description, certain terms have been used for the purposes of brevity, clarity, and understanding; however, since these terms are for descriptive purposes and are intended to be broadly interpreted, they should not be unnecessarily limited beyond the requirements of the prior art. Furthermore, this disclosure has been described with reference to specific embodiments. It should be understood that this description is exemplary and not restrictive, as the scope of the invention is not limited to the precise details shown or described. Possible modifications and alterations will occur to others upon reading and understanding this disclosure, and it should be understood that this disclosure includes all such modifications and alterations and their equivalents.

[0077] The features, discoveries and principles of this disclosure, the manner of constructing, arranging and using steering knuckles for self-steering axle / suspension systems of heavy vehicles, the features of their construction and arrangement, and the advantageous, new and useful results obtained are now described; new and useful structures, devices, elements, arrangements, components and combinations are set forth in the appended claims.

Claims

1. A steering knuckle for a self-steering axle / suspension system of a heavy-duty vehicle, the heavy-duty vehicle having a drum braking system, the steering knuckle comprising: A body, the body being adapted to receive the kingpin of the self-steering axle / suspension system for pivotally connecting the steering knuckle to the axle of the self-steering axle / suspension system; A main shaft extending from the outer surface of the body; A first arm extends from the inner surface of the body and has an opening for receiving a first end of the master pin. The second arm extends from the inner surface of the body and has an opening coaxially aligned with the opening of the first arm for receiving the opposite second end of the kingpin. as well as A drum brake system component mounting structure, the drum brake system component mounting structure comprising: At least one brake shoe mounting opening, and The cam tube opening and the drum brake system component mounting structure mount one or more components of the drum brake system, wherein the body, the first arm, the second arm, and the drum brake system component mounting structure are integrally formed, the distance between the outer end of the bearing shoulder of the spindle and the vertical axis extending through the opening of the first arm and the opening of the second arm is within 7.5 inches to 10.5 inches, and the distance between the vertical centerline of the at least one brake shoe mounting opening and the vertical axis is within 4.0 inches to 7.0 inches.

2. The knuckle for a self-steering axle / suspension system of a heavy-duty vehicle of claim 1, wherein, The spindle is fixed to the body by a single weld.

3. The knuckle for a self-steering axle / suspension system of a heavy-duty vehicle of claim 2, wherein, The individual welded part is a friction welded part.

4. The knuckle for a self-steering axle / suspension system of a heavy-duty vehicle of claim 1, wherein, The distance between the outer end of the bearing shoulder of the spindle and the vertical axis extending through the openings of the first arm and the second arm is between 8.5 inches and 9.5 inches.

5. The steering knuckle for a self-steering axle / suspension system for heavy vehicles according to claim 1, further comprising a separate tie rod arm removably connected to the body of the steering knuckle without welding.

6. The steering knuckle of the self-steering axle / suspension system for heavy vehicles according to claim 5, wherein the tie rod arm is connected to the body by a first fastener and a second fastener, the first fastener being positioned axially and vertically offset from the second fastener.

7. The knuckle for a self-steering axle / suspension system of a heavy-duty vehicle of claim 6, wherein, The first fastener is positioned axially offset from the second fastener by approximately 90 degrees.

8. The steering knuckle for a self-steering axle / suspension system for heavy vehicles according to claim 7, wherein, The first fastener and the second fastener are bolts.

9. The steering knuckle for a self-steering axle / suspension system for heavy vehicles according to claim 1, wherein, The at least one brake shoe mounting opening is adapted to install an anchor pin for the pivot connection of the brake shoe.

10. The steering knuckle for a self-steering axle / suspension system for heavy vehicles according to claim 1, wherein, The drum brake system component mounting structure includes a pair of brake shoe mounting openings adapted to mount a pair of anchor pins for pivotal connection of the pair of brake shoes.

11. The steering knuckle for a self-steering axle / suspension system for heavy vehicles according to claim 1, wherein, The cam tube opening is adapted to mount the cam tube of the cam support assembly.

12. The steering knuckle for a self-steering axle / suspension system for heavy vehicles according to claim 1, wherein the body further includes a protrusion extending outward from the body, and the spindle is fixed to the outer end of the protrusion by friction welding.

13. The steering knuckle of the self-steering axle / suspension system for heavy vehicles according to claim 1, the steering knuckle further comprising a structure for receiving one or more components of a tire inflation system, the structure including a first axial opening extending through the body at a location located radially inward of the main shaft, the first axial opening being sized such that pneumatic lines of the tire inflation system can pass through the first axial opening and enter the interior of the main shaft.

14. The steering knuckle of the self-steering axle / suspension system for heavy vehicles according to claim 13, further comprising an exhaust system incorporated therein, the exhaust system comprising: A second axial opening extends through the body at a location located radially inside the main shaft; as well as A pneumatic check valve is attached to the second axial opening adjacent to the inner surface of the main body, the pneumatic check valve allowing pressurized air to be discharged from the interior of the spindle to the atmosphere.

15. The steering knuckle of the self-steering axle / suspension system for heavy vehicles according to claim 1, further comprising an exhaust system incorporated therein, the exhaust system comprising: An axial opening extends through the body at a location located radially inside the main shaft; as well as A pneumatic check valve is attached to the axial opening adjacent to the inner surface of the main body, the pneumatic check valve allowing pressurized air to be discharged from the interior of the spindle to the atmosphere.

16. The steering knuckle for a self-steering axle / suspension system for heavy vehicles according to claim 1, wherein, The drum brake system component mounting structure, the main body, the first arm, and the second arm are integrally formed by forging.

17. The steering knuckle for a self-steering axle / suspension system for heavy vehicles according to claim 1, wherein, The steering knuckle provides a wheel steering angle of up to thirty degrees for the wheels mounted on the main shaft.

18. The steering knuckle for a self-steering axle / suspension system for heavy vehicles according to claim 1, wherein, The self-steering axle / suspension system is a trailing arm self-steering axle / suspension system, and the vertical axis extending through the openings of the first arm and the second arm is located in front of the axial center axis of the main shaft.

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