Support unit with quick-change load wheel unit

Abstract

Boom unit for a material handling vehicle, comprising a frame (12) supporting a radar arm (30), a boom housing (135) connected to the radar arm (30) and a load wheel unit (128), wherein the boom housing (135) comprises a pair of bearing plates (136a, 136b) which are laterally spaced apart from each other and form a load wheel opening (137) between them, and a crossbeam (170) extending across the load wheel opening (137) between the bearing plates (136a, 136b), includes wherein the load wheel unit (128) comprises a first and a second lateral support element (142a,142b) which are spaced laterally apart from each other, at least two rollers (144, 146) which are rotatably arranged between the first and the second lateral support element (142a, 142b) to form at least one load wheel, two axles (148,150) which carry the at least two rollers on the first and second lateral support elements (142a,142b), and a connecting structure (162) with a block element (164) that extends between and connects the first and second lateral support elements (142a, 142b), includes wherein the block element (164) has a lower surface (181) that touches and fits an upper surface (187) of the crossbeam (170) to form a fixed connection between the connecting structure (162) and the crossbeam (170) and thus with the material handling vehicle when the load wheel unit is connected to the material handling vehicle.

Description

[0001] The present invention relates generally to material handling vehicles, such as forklifts, and more particularly to a quick-change load wheel unit that can be quickly attached to and removed from a wheel arm or boom of a material handling vehicle.

[0002] Forklift trucks, such as ride-on reach trucks and reach trucks, are typically equipped with a pair of forward-extending outriggers mounted outboard of the truck's vertically movable forks. There, they do not interfere with the forks being lowered to the ground or interfere with any load carried on the forks. The outriggers each support one or more load wheels to support the weight of the truck and any load carried by the forks. After a certain period of use, the load wheels typically wear out or become damaged and must be replaced.

[0003] A known design for a base foot unit of a support arm with load wheels of a forklift is shown in US design patents US 505 763 S and US 499 853 S and also in published application US 2005 / 0 034 929 A1. The base foot unit has a mounting plate, a base foot and a load wheel unit. The base foot has an integrally molded mounting portion and a foot portion that extends laterally from the mounting portion and crosses in a direction of approximately 90° such that the foot portion extends forwardly from the mounting portion and the forklift at the distal end thereof. A load wheel unit includes a pair of load wheel plates that are mirror images of each other. They have inner surfaces that contact the outer surface of the distal end of the foot portion of the base foot.The load wheel plates are attached to the base leg using threaded fasteners. An elongated opening extends transversely through each load wheel plate to accommodate the load wheels. The elongated openings are shaped to accommodate different numbers, sizes, and types of load wheels, which are rotatably mounted and supported between the load wheel plates.

[0004] To remove the load wheel assembly from the wheel arm, the fasteners securing the load wheel plates to the leg portion of the base leg are removed to release the wheel plates. For reassembly, load wheels of the required size and type are placed between the load wheel plates. These are then moved into position so that the plates can be reattached to the leg portion of the base leg using the previously removed fasteners. Because this type of repair is typically performed in the field, it can be difficult and requires caution when manipulating the load wheels and load wheel plates for reassembly.

[0005] In another arrangement for attaching load wheels to a wheel arm, a mounting structure comprises a weldment with spaced-apart bearing plates and is located at the end of the wheel arm. Axle plates, located in openings in each bearing plate, support wheel axles for the two spaced-apart wheels. Changing wheels requires removing the axles, resulting in loosening the wheels as well as various washers and bearings carried on the wheels and axles. Repair performed in a work environment can be difficult because the process of fitting the spare wheels into the bearing plates requires manipulating various parts on the axles as the axles are moved into position in the axle plates.Such repair may be further complicated by the location of the load wheel structure adjacent to the ground surface, as this restricts access to the parts positioned between the bearing plates.

[0006] From US 2008 / 0 308 359 A1, a load wheel unit for a boom or for a support arm of a forklift truck is known, wherein the design of the load wheel unit and the boom or support arm allows rapid installation of the load wheel unit. The load wheel unit has a structure whose upper surface can be connected to a lower surface of a structure of the boom or support arm. In order to bring the upper surface of the structure of the load wheel unit into contact with the lower surface of the structure of the boom or support arm and to connect them, the boom or support arm is lifted from the ground on which the forklift truck is standing and the load wheel unit is inserted from below into an opening in the boom or support arm. After the load wheel unit and the boom or support arm are connected, the part of the forklift truck that has been lifted from the ground is lowered onto the ground.

[0007] The invention is aimed at enabling a rapid installation of a load wheel unit into a material handling vehicle (forklift) with few work steps.

[0008] A further object of the invention is to provide an arrangement and method that enables a quick and effective change of the load wheel assembly on a support arm (boom) of a forklift truck (material handling vehicle). This object or these objects are achieved by independent claims 1 or 10 or by a method according to claim 13.

[0009] According to one aspect of the present invention, a boom unit for a material handling vehicle is provided, comprising a frame supporting a wheel arm and a boom housing connected to the wheel arm. The boom housing may include a pair of bearing plates laterally spaced apart and defining a load wheel opening therebetween, and a crossbeam extending between the bearing plates across the load wheel opening.There may be provided a load wheel unit comprising first and second laterally spaced lateral support members, at least one roller, especially two rollers, rotatably mounted between the first and second lateral support members to form at least one load wheel, an axle, especially two axles, carrying the at least one roller on the first and second lateral support members, and a connecting structure extending between and connecting the first and second lateral support members. The connecting structure may have at least one portion that engages and mates with the crossbeam to provide a substantially fixed connection between the connecting structure and the crossbeam and thus to the material handling vehicle.

[0010] According to another aspect of the invention, a material handling vehicle is provided having a quick-change load wheel unit. The material handling vehicle includes a frame, a mast unit connected to the frame, and a pair of outriggers connected to the frame and extending from the front of the vehicle. Each of the outriggers may include a mounting structure comprising a pair of laterally spaced bearing plates. These define a load wheel opening for receiving a quick-change load wheel unit. The mounting structure includes a crossbeam extending laterally across the load wheel opening.The load wheel unit may include first and second laterally spaced lateral support members, a pair of rollers rotatably mounted between the first and second lateral support members to form a load wheel pair, an axle supporting each roller on the first and second lateral support members, and a block member extending between and connecting the first and second lateral support members. The lateral support members may be rotatably supported relative to the block member. The block member has at least a portion that engages and mates with the crossbeam to form a substantially fixed connection between the block member and the crossbeam and thereby the material handling vehicle.

[0011] According to another aspect of the invention, a method of attaching a load wheel assembly to a boom for a material handling vehicle is provided. The boom may include a boom housing having a pair of laterally spaced bearing plates defining a load wheel opening for receiving a load wheel assembly, and a crossbeam extending laterally across the load wheel opening. The load wheel assembly may include at least one roller supported on an axle between a pair of lateral support members and a connecting structure extending between the pair of lateral support members.The method includes positioning the load wheel unit in the load wheel opening with the connecting structure disposed above the crossbeam, engaging at least one threaded fastener between the connecting structure and the crossbeam, and rotating the connecting means to pull the crossbeam into engagement with the connecting structure.

[0012] While the claims substantially point out and distinctly claim the present invention, it is believed that the present invention will be better understood from the following description taken in conjunction with the drawings, in which like reference characters designate like elements. Fig. 1 a perspective view of a typical forklift truck, Fig. 2 a perspective view of an end of a wheel arm of the forklift truck of the Fig. 1, Fig. 3 one to Fig. 2 similar view, with the load wheel unit removed from the wheel arm, Fig. 3a and Fig. 3b to Fig. 3 similar views, but showing removable bearing plates and an alternative fastening means and connecting structure, Fig. 4 is an exploded perspective view of the load wheel unit, Fig. 5 is an enlarged sectional view taken along line 5 - 5 in Fig. 6, Fig. 6 a side view of an end area of ​​the wheel arm, showing a position for replacing the load wheel unit, Fig. 7 is a perspective view of a load wheel unit and a single wheel inserted horizontally into a load bearing structure, Fig. 8 is a perspective view of the end of a wheel arm of the forklift truck with an embodiment of a load wheel unit of the invention shown disassembled from the wheel arm, Fig. 9 an exploded view of the load wheel unit of the Fig. 8, Fig. 10 is an exploded view of an alternative embodiment of the load wheel unit of the Fig. 9, Fig. 11 a cross-section showing the load wheel unit of the Fig. 10 arranged in a holding tool, Fig. 12 a cross-section showing the load wheel unit of the Fig. 10 in a position transferred from the holding tool into a load wheel opening of a boom housing, Fig. 13 a perspective view of the load wheel unit of the Fig. 10, which is positioned in the load wheel opening of the boom housing before engagement of a connecting structure of the load wheel unit with a fastening structure of the wheel arm, Fig. 14 a sectional view of the load unit of the Fig. 10, which engages with the wheel arm mounting structure.

[0013] In the following detailed description, reference is made to the drawings. It is obvious that other embodiments are possible and that changes may be made without departing from the spirit and scope of the claims.

[0014] Fig. 2, Fig. 3, Fig. 3A, Fig. 3B, Fig. 4, Fig. 5, Fig. 6 and Fig. 7 with associated description specifically related to the relative arrangement of the load wheel unit to the boom (wheel arm) are not the subject of the patented invention.

[0015] It will now Fig. 1, which shows a material handling vehicle. The vehicle, in the illustrated embodiment, comprises a ride-on reach truck, hereinafter referred to as a forklift 10. The forklift 10 includes a frame 12, a drive mechanism 14 supported by the frame 12, a mast unit 16 connected to the frame 12, an operator compartment 18, and an overhead guard 20. The drive mechanism 14 includes a power unit 22 with a battery (not shown). This power unit 22 serves to power a hydraulic motor (not shown) connected to a steerable driven wheel 24 and hydraulic motors (not shown) that supply power to several different systems.

[0016] The forklift is supported at four points. These are formed by the steerable, driven wheel 24 arranged on the left rear side of the power unit 22, a steering roller 26 arranged on the right rear side of the power unit 22, and two load wheel units 28 which are supported on a pair of outrigger units (wheel arms) 30 (of which Fig. 1 only the left-hand support arm is visible). The latter extend from the power unit 22 to the front of the forklift truck 10. The support arms 30 are attached to the power unit 22 in such a way that they extend outward beyond the sides of the mast unit 16. This allows a pair of forks 32 to be lowered between the support arms 30 without affecting the ground, and the support arms 30 do not affect any load carried on the forks.

[0017] Now additionally on Fig. 2, each wheel arm 30 includes a forwardly extending solid steel beam or arm member 34. A load bearing structure 36 includes a pair of bearing plates 36a, 36b and is disposed at the forward end of the arm member 34, with the load wheel assembly 28 disposed between the bearing plates 36a, 36b. The bearing plates 36a, 36b are illustrated as solid extensions of the arm member 34, for example, by the bearing plates 36a, 36b and the arm member 34 comprising a weld, or by being cast as a single, integral unit. It should be noted, however, that no special structure is provided for forming the bearing plates 36a, 36b at the end of the arm member 34. The bearing plates 36a, 36b may, for example, comprise separate plate elements attached to the end of the arm element 34, for example by screwing the individual bearing plates 36a, 36b to the arm element 34.In any case, assembly and disassembly procedures described for the load wheel units 28 do not require removal or reattachment of the bearing plates 36a, 36b from or to the arm member 34.

[0018] Referring to the Fig. 3 and Fig. 4, the illustrated load wheel unit 28 includes a first side member 42a and a second side member 42b laterally spaced from the first side member 42a. The side members 42a, 42b are elongated with a major longitudinal axis L and a minor elevation axis H. First and second rollers or wheels 44, 46 are rotatably supported on respective first and second axles 48, 50 to form a roller structure 43. The first and second axles 48, 50 extend transversely between the side members 42a, 42b, with the ends of the axles 48, 50 being received in openings 49a, 49b in the respective side members 42a, 42b. Each of the wheels 44, 46 may comprise known load wheels including a tire 52 carried on a bushing portion 54, the bushing portion 54 including a bearing 56 for cooperation with a corresponding axle 48, 50.It should be noted that the roller structure 43 may comprise a structure other than that specifically described herein, and that the roller structure 43 may comprise any load-bearing unit that provides a ground-engaging component to reduce friction between the support arm 30 and the ground when the forklift 10 is steered along the ground. Furthermore, while two wheels 44, 46 are shown in the illustrated embodiment, the roller structure may have a single wheel or more than two wheels, depending on the requirements of the specified application.

[0019] The roller structure 43 is retained in the side members 42a, 42b by a retaining means shown as comprising a type of snap ring 58, known as a circlip snapped into annular slots at the ends of the axles 48, 50. Alternatively, the retaining structure may comprise other fastening devices connected to the axles 48, 50 or the side members 42a, 42b, as will be known to those skilled in the art. The retaining structure may even simply be adhesive tape affixed over the openings 41a, 41b in the respective side members 42a, 42b, or wrapped around the roller structure 43 and the side members 42a, 42b prior to installation. Whichever retaining or retention structure is used, the unit comprising the roller structure 43 and the retained side members 42a, 42b defines an assembled roller assembly 60 for the load wheel assembly 28.

[0020] The load wheel unit 28 further includes a connecting structure 62 for providing a substantially fixed connection between the load-bearing structure 31 and the mounted roller unit 60. The illustrated connecting structure 62 includes a block member 64 fixedly attached to a pivot pin 66. The block member 64 may be attached to the pivot pin 66 by any conventional method, such as welding.

[0021] Alternatively, the block member 64 and the pivot pin 66 may be formed as a single member. The pivot pin 66 extends transversely to the longitudinal axis L and the vertical axis H and is secured for rotation to the frame structure 40 in journal holes 68a, 68b. These are formed in the respective side members 42a, 42b, generally in the center of the side members 42a, 42b, i.e., between the first and second wheels 44, 46, as shown. The ends of the pivot pin 66 engage bearing members 68 disposed in the journal holes 68a, 68b. The pivot pin 66 forms a pivoting structure about which the assembled roller unit 60 can rotate.

[0022] Referring to the Fig. 2 and Fig. 3, the load-bearing structure 36 includes a mounting structure comprising a crossbeam 70 extending between and fixedly connected to the bearing plates 36a, 36b. The bearing plates 36a, 36b and the crossbeam 70 may be joined together by welding. Alternatively, they may be formed as a single piece or casting. The crossbeam 70 includes an opening 72 through which a threaded fastener 74 of the connecting structure 62 may extend to engage a threaded opening 76 formed through a top surface 82 of the block member 64. As shown in FIGS. Fig. 2 to 4, a single downwardly inserted bolt secures the load wheel unit 28 to the load bearing structure 36. It should be noted that a bolt may be inserted upwardly into the threaded opening 72 for receiving the bolt, and that other fastening means may be used to secure the load wheel unit 28 to the load bearing structure 36. For example, a bolt S may be formed on either the load wheel unit 28 or the crossbeam 70 to be received in a receiving opening in the other structure. In this case, the bolt S is secured by means of a roll pin RP or otherwise, see Fig. 3a, fixed. Fig. 3a also shows individual bearing plates 36a, 36b, which can be anchored to the arm element 34.

[0023] Referring to Fig. 5, the crossbeam 70 includes a pair of openings 84, each opening 84 including a lower opening portion 84a extending upwardly from a lower surface 86 of the crossbeam 70 and an upper opening portion of smaller diameter 84b extending from the lower opening portion 84a to an upper surface 87 of the crossbeam 70. The block member 64 includes a pair of pins 80 extending from its upper surface 82 to engage the lower opening portions 84a of the crossbeam 70. Each of the bearing plates 36a, 36b additionally includes a downwardly directed cutout portion 85 (in Fig. 3, only one is shown) to receive correspondingly textured upper surfaces of the side members 42a, 42b. The bearing plates 36a, 36b and the crossbeam 70 define a downwardly directed opening of the load-bearing structure 36. During a fastening operation of the load-bearing unit 28 to the load-bearing structure 36, the load wheel unit 28 and the side members 42a, 42b are positioned relative to one another to position the side members 42a, 42b in the cut-out areas 85. In addition, the upper surface 82 of the block member 64 is moved into engagement with the lower surface 86 of the crossbeam 70, see Fig. 3.

[0024] The pins 80 slide into the openings of the lower opening portions 84a on the lower surface 86 of the crossbeam 70. They include tapered ends to facilitate alignment of the block member 64 with the crossbeam 70 such that the opening 76 in the block member 64 is aligned with the opening 72 in the crossbeam 70. The fastener 74 can then be inserted through the opening 72 and threaded into the opening 76 to hold the block member 64 in engagement with the crossbeam 70. The pins 80 provide a structure that, in combination with the fastener 74, substantially prevents relative shear movement between the block member 64 and the crossbeam 70 and further resists lateral movement of the assembled roller assembly 60 relative to the load-bearing structure 36.

[0025] Other arrangements will be known to those skilled in the art to substantially prevent relative shearing movements between the block member 64 and the crossbeam 70. In Fig. 3b, for example, shows a connection by means of a pin T and a groove (not shown). Fig. 3b also shows individual bearing plates 36a, 36b, which can be screwed to the arm element 34.

[0026] As previously stated, alternatives for securing the block member 64 to the crossbeam 70 include, for example, inserting the fastener 74 upwardly through the block member 64 and screwing it into the crossbeam 70, as well as a bolt and roll pin. Other fastening arrangements will be apparent to those skilled in the art in light of this description.

[0027] With reference to Fig. 6, a procedure for replacing a load wheel unit 28 will now be described. The end of the wheel arm 30 may initially be lifted from the ground surface 88, for example, by applying a lifting force F to a portion of the wheel arm 30, to create an access space 90 between the ground surface 88 and the lower edge 2 of the load support structure 36. The fastener 74 may be removed to enable separation of the block member 64 from the crossbeam 70 so that the load wheel unit 28 can be lowered downwardly from the load support structure 36 as an assembled unit. A punch and hammer may be used in the openings 84 to assist removal. Subsequently, a replacement load wheel unit 28 may be inserted by moving it into the access space 90 and positioning it upwardly to engage the load support structure 36, as previously described.

[0028] Alternatively, the fastener 74 may first be removed and the wheel arm 30 raised so that the wheel arm 30 is lifted off the load wheel unit 28. The replacement load wheel unit 28 is subsequently positioned in the access space 90, and the end of the wheel arm 30 may be lowered to engage the crossbeam 70 of the load support structure 36 with the block member 64 of the load wheel unit 28.

[0029] In each case, at least one fastener 74 extending between the wheel arm 30 or the boom and the load wheel unit 28 is released, and an original load wheel unit 28 is detached from the wheel arm 30. A replacement load wheel unit 28 is engaged with the wheel arm 30. The at least one fastener 74 is engaged between the replacement load wheel unit 28 and the wheel arm 30 to hold the load wheel unit 28 to the wheel arm 30.

[0030] While reference has been made to vertical movement between a wheel unit and the load-bearing structure, it is clear that horizontal movement can also be used to remove and replace a load-bearing wheel unit. Such horizontal movement requires less lifting of the load-bearing structure. The movement between the load-bearing wheel unit and the load-bearing structure can be to the side or from the front of the load-bearing structure. Fig. For example, in Figure 7, a load wheel unit 28' with a single wheel 44' is shown, which is inserted into the load bearing structure 36'. The load wheel unit 28' has a pin T that fits into a groove M on the load bearing structure 36'. The components of the Fig. 7, which correspond to the same elements in the previously described embodiments, are provided with “dashed” like reference numerals (e.g. 36' instead of 36).

[0031] From the foregoing description, it is apparent that the structure of the load wheel unit 28 enables efficient load wheel replacement by providing a straightforward connecting structure 62. This includes, for example, the single fastener 74 that engages the block member 64 to attach and remove the load wheel unit 28. This requires minimal manipulation of elements during a replacement or repair operation. Furthermore, the pins 80 or bolt T of the connecting structure 62 simply engage the openings 84 or groove M of the crossbeam 70 to facilitate positioning of the load wheel unit 28 relative to the load support structure 36, while also strengthening the connection between the two components.

[0032] Referring to the Fig. 8 and Fig. 9, an embodiment of a boom unit of the invention is shown, which includes a quick-change load wheel unit. The quick-change load wheel unit can be incorporated into a boom or wheel arm 30 of a material handling vehicle, such as a forklift 10, as shown in Fig. 1. Elements of the boom unit of the Fig. 8 and Fig. 9, which correspond to the elements described above, are identified by the same reference numbers, each increased by 100.

[0033] How Fig. 8, a load-bearing structure 136 defines a boom housing 135. This includes a pair of bearing plates 136a, 136b that are laterally spaced from each other and extend in a longitudinal direction of the wheel arm 30 ( Fig. 1). The bearing plates 136a, 136b define an intermediate load wheel opening 137. A crossbeam 170 extends through a longitudinally central region of the load wheel opening 137 and includes opposite ends fixedly secured to the bearing plates 136a, 136b. The crossbeam 170 may be welded to the bearing plates 136a, 136b to form the boom housing 135 as a solid weldment. Additionally, a boom tip 139 may be attached to the load support structure 136, for example, by means of bolts (not shown) that secure the boom tip 139 to the bearing plates 136a, 136b to enclose an outer end of the load wheel opening 137.

[0034] Furthermore, with reference to Fig. 9, the boom unit includes a load wheel unit 128 with lateral support members. These comprise a first side member 142a and a second side member 142b laterally spaced from the first side member 142a. First and second rollers or wheels 144, 146 are rotatably mounted on respective first and second axles 148, 150. The first axle 148 and the second axle 150 extend transversely between the side members 142a, 142b, with the ends of the axles 148, 150 being received in openings 149a, 149b in the respective side members 142a, 142b. The wheels 144, 146 may comprise known load wheels including a tire 152 carried on a sleeve portion 154 that includes a bearing 156 for engagement with a corresponding axle 148, 150.Additionally, a bearing shield or spacer 161 may be provided adjacent an outer end of each of the bearings 156 to space the bearings 156 from the corresponding side members 142a, 142b.

[0035] The axles 148, 150 are retained in engagement with the openings 149a, 149b by a retaining means, for example, a snap ring 158, i.e., a circlip, which engages an annular slot or groove in each end of the axles 148, 150. The openings 149a, 149b are preferably formed with a D-shaped cross-section for receiving similarly shaped ends of the axles 148, 150. A recess 159 is formed in an outer end of each of the openings 149a, 149b for receiving the snap ring 158 substantially flat within the corresponding side members 142a, 142b.

[0036] The load wheel unit 128 further includes a connecting structure 162 for providing a substantially fixed connection between the load-bearing structure 136 and the load wheel unit 128. The connecting structure 162 comprises a block member 164 and includes pivot ends 166 extending from opposite lateral sides of the block member 164. The pivot ends 166 may be formed integrally with the block member 164. For example, the block member 164 may be a machined part with the pivot ends 166 formed at opposite ends thereof. Alternatively, the pivot ends 166 may comprise the ends of a pivot pin (not shown) extending through or connected to the block member 164.The pivot pin ends 166 engage pivot openings 168a, 168b formed in the respective side members 142a, 142b generally centrally of the side member 142a, 142b, that is, between the first and second wheels 144, 146, as shown in FIGS. Fig. 8 and Fig. 9. The pivot pin ends 166 further engage bearing elements 168 disposed within the pin openings 168a, 168b. The pivot pin ends 166 engaging the bearing elements 168 form a pivoting structure about which the load wheel unit 128 is rotatable relative to the load-bearing structure 136.

[0037] The block element 164 of the connecting structure 162 is configured to engage the crossbeam 170 of the load-bearing structure 136. In particular, a lower surface 181 ( Fig. 9) of the block element 164 on an upper surface 187 ( Fig. 8) of the crossbeam 170. The block member 164 includes a pair of laterally spaced through openings 176 to receive a pair of shoulder bolts 174 therethrough. The crossbeam 170 includes a pair of threaded openings 172 (in Fig. 8, only one is shown) to receive a threaded end of the shoulder bolts 174, as described below. The shoulder bolts 174 are preferably sufficiently strong to transfer load forces from the load-bearing structure 136 at the end of the wheel arm 30 to the load wheel assembly 128. The shoulder bolts 174 may, for example, comprise a metric M 12 x 1.75 steel threaded bolt with a thread length of approximately 18 mm and a shoulder length of approximately 50 mm. The shoulder bolts 174 preferably further have a property class designation of 12.9, i.e., a minimum tensile strength of approximately 1100 MPa and a minimum shear strength of approximately 660 MPa.

[0038] Referring to Fig. 10, the boom unit may include a load wheel unit 128' having axles 148', 150' and side members 142a', 142b' in an alternative configuration to enable the load wheel unit 128' to support a greater load. In particular, the side members 142a', 142b' may be formed with openings 149a', 149b', respectively, which do not have the Fig. 9. This means that the openings 149a', 149b' can be formed from a continuous surface extending between the opposite planar sides of the side members 142a', 142b'. The openings 149a', 149b' in the side members 142a', 142b' therefore provide a larger surface area for the engaging ends of the axles 148', 150'. Furthermore, the ends of the axles 148', 150' can be formed without a groove or other structure for receiving the snap ring 158. They can form a continuous surface for engagement with the corresponding surfaces of the openings 149a', 149b'. The additional load-bearing area formed by the contact between the ends of the axles 148', 150' and the surfaces of the openings 149a', 149b' appears to provide additional load-bearing capacity of the side members 142a', 142b' in the region of the ends of the axles 148', 150'.As in the with reference to the . Fig. 8 and Fig. 9, the openings 149a' 149b' are preferably formed with a D-shaped cross-section to accommodate similarly shaped ends of the axles 148', 150'.

[0039] Since the information relating to Fig. 10 does not include a retaining structure, such as the snap ring 158, to retain the side members 142a', 142b' in engagement with the ends of the axles 148', 150' and with the connecting structure 162' when the load wheel unit 128' is not in the load wheel opening 137 ( Fig. 8), a holding tool 194 may be provided to hold the load wheel unit 128' in an assembled state, that is, with side members 142a', 142b' engaging the axles 148', 150' and the connecting structure 162', when the load wheel unit 128' is not disposed in the load wheel opening 137 ( Fig. 8). The holding tool 194 may include a C-shaped frame 196 with an abutment structure for the opposing side members. The abutment structure includes side plates 196a, 196b and a base plate 196c extending between and oriented perpendicular to the side plates 196a, 196b. The side plates 196a, 196b may be formed integrally with the base plate 196c, for example, by being formed from a single plate or cast as a unitary member. Alternatively, they may include a weld. It should further be noted that the holding tool 194 may have configurations other than the particular C-shaped structure described herein, such that an alternative configuration may provide the function of the holding tool 194 for installing and / or removing the load wheel assembly 128' into and from the load wheel opening 137, as described below.

[0040] Furthermore, with reference to Fig. 11, the holding tool 194 includes a threaded screw member 198 having a threaded shaft 198a and a gripping arm 198b. A first threaded nut 200 is threaded onto the threaded shaft 198a and disposed between the handle 198b and an upper surface 202 of the base plate 196c. A second threaded nut 204 is threaded onto the threaded shaft 198a on a side of the base plate 196c opposite the first threaded nut 200. The holding tool 194 can engage the load wheel assembly 128' by at least partially threading the threaded shaft 198a into a threaded opening 206 of the block member 164'. The first threaded nut 200 can be rotated on the threaded shaft 198a to move the first threaded nut 200 on the threaded shaft 198a to a position toward the block member 164'.In this position, the assembled load wheel unit 128' is proportioned such that at least an upper portion of the side members 142a, 142b engages corresponding inner surfaces 197a, 197b of the side plates 196a, 196b, as shown in FIG. Fig. 11. The lower threaded nut 204 may be arranged in a predetermined fixed position to define a stop position for upward movement of the screw member 198 through the base plate 196c. The second threaded nut 204 may further prevent the screw member 198 from being separated from the base plate 196c when the base plate 196c is not engaged with the load wheel assembly 128'.

[0041] The load wheel unit 128' held within the holding tool 194 comprises a pre-assembled load wheel unit 207 ( Fig. 7) for installation in the boom housing 135. As in Fig. 11, the preassembled load wheel unit 207 is positioned with the side plates 196a, 196b engaging the upper portions of the bearing plates 136a, 136b. The side plates 196a, 196b include corresponding recessed areas 208a, 208b for receiving the upper portions of the bearing plates 136a, 136b. A neck portion 209a, 209b of the side plates 196a, 196b extends along an outer portion of the bearing plates 136a, 136b to laterally align the holding tool 194 relative to the boom housing 135. The inner surfaces 197a, 197b of the side plates 196a, 196b of the holding tool are further substantially aligned with the inner surfaces of the bearing plates 136a, 136b in the cut-out or recessed areas 185 formed in the bearing plates 136a, 136b for receiving a corresponding side member 142a, 142b and for accommodating rotational movement of the side members 142a', 142b'.

[0042] As in Fig. 12, the load wheel assembly 128' can be lowered from the holding tool 194 into the load wheel opening 137. To do this, the first threaded nut 200 is rotated to move the load wheel assembly 128' downward away from the base plate 196c and to allow the wheels 144, 146 to come into contact with a support surface, such as a floor surface. The wheels 144, 146 can be arranged on either side of the crossbeam 170. Subsequently, the screw member 198 can be rotated to release the threaded shaft 198a from the threaded opening 206 in the block member 164. The holding tool 194 can be removed from the boom housing 135. After lowering the load wheel unit 128' into the load wheel opening 137, the lower surface 181 of the block element 164' is spaced above the upper surface 187 of the crossbeam 170. The bearing plates 136a, 136b can further rest on the support surface before the block element 164' abuts the crossbeam 170.

[0043] During an assembly operation in which the block member 164' is engaged with the crossbeam 170, the shoulder bolts 174 can be inserted through the through holes 176 and screwed into the threaded holes 172, see Fig. 13. The shoulder bolts 174 can further be rotated to pull the crossbeam 170 toward the block member 164'. This lifts the load-bearing structure 136 off the support surface. For example, the shoulder bolts 174 can be alternately rotated to alternately move the crossbeam 170 a short distance upward toward the block member 164 until the upper surface 187 of the crossbeam 170 abuts and mates with the lower surface 181 of the block member 164', thereby forming a substantially rigid connection between the connecting structure 162' and the crossbeam 170, as shown in Fig. 14 is shown.

[0044] It should be noted that the information relating to the Fig. 8 and Fig. 9 can be attached to the load-bearing structure 136 by a substantially similar process. The exception is that the load-bearing structure 136 can be positioned in the load-bearing opening without the use of the holding tool 194. The load-bearing structure 136's load-bearing units 128, 128' can therefore be attached to the load-bearing structure 136 without the use of a lifting tool or other device to support the ends of the bearing plates 136a, 136b spaced from the support surface when the load-bearing structure 128, 128' is arranged in its installed position relative to the load-bearing structure 136.

[0045] The load wheel unit 128, 128' can further be removed by loosening the shoulder bolts 174. This results in the bearing plates 136a, 136b coming to rest on the support surface. In the case of the load wheel unit 128', the holding tool 194 can be positioned over the load wheel unit 128' after removing the shoulder bolts 174. To remove the load wheel unit 128' from the load wheel opening 137, the screw element 198 can be inserted into the threaded opening 206 in the block element 164 ( Fig. 12) and turn the first threaded nut 200 to move the load wheel unit 128' upwards into the Fig. 11 shown position.

Claims

[1] Boom unit for a material handling vehicle, comprising a frame (12) carrying a wheel arm (30), a boom housing (135) connected to the wheel arm (30) and a load wheel unit (128), wherein the boom housing (135) has a pair of bearing plates (136a, 136b) which are laterally spaced from each other and form a load wheel opening (137) therebetween, and a crossbeam (170) extending across the load wheel opening (137) between the bearing plates (136a, 136b), includes, wherein the load wheel unit (128) comprises a first and a second lateral support element (142a, 142b) which are laterally spaced from each other, at least two rollers (144,146) rotatably arranged between the first and second lateral support elements (142a,142b) to form at least one load wheel, two axles (148,150) which support the at least two rollers on the first and second lateral support elements (142a,142b), and a connecting structure (162) with a block element (164) extending between and connecting the first and second lateral support elements (142a, 142b), includes, wherein the block member (164) has a lower surface (181) contacting and mating with an upper surface (187) of the crossbeam (170) to form a fixed connection between the connecting structure (162) and the crossbeam (170) and thereby to the material handling vehicle when the load wheel unit is connected to the material handling vehicle. [2] Boom unit according to claim 1, wherein the connecting structure (162) is held in contact with the crossbeam (170) by means of a fastening means (174) which can be releasably fastened. [3] The boom unit of claim 2, wherein the attachment means (174) extends through an opening (172) formed at least partially through the connecting structure (162) and the crossbeam (170). [4] A boom unit according to claim 3, wherein the fastening means (174) extends vertically between the connecting structure (174) and the crossbeam. [5] The boom unit of claim 1, wherein the lateral support members (142a, 142b) each have an opening (149a, 149b) for receiving a corresponding end of the axle (148, 150), each opening receiving the corresponding ends of the axle in sliding engagement, and wherein the lateral support members (142a, 142b) are positioned contacting an inner surface (147a, 147b) of one of the bearing plates to maintain the lateral support members (142a, 142b) in engagement with the ends of the axle (148, 150). [6] A boom unit according to claim 5, wherein the inner surfaces (147a, 147b) of the bearing plates comprise recessed areas for receiving the lateral support elements. [7] Boom unit according to claim 1, wherein the block element (164) of the connecting structure (162) extends transversely between the lateral support elements. [8] A boom unit according to claim 7, comprising a pivot opening (168a, 168b) formed in each of the lateral support members (142a, 142b) and pivot ends extending from opposite sides of the block member (164) and engaging the pivot openings (168a, 168b). [9] Boom unit according to claim 8, wherein the rollers (144,146) are carried on opposite sides of the pivot ends (166) with respect to a longitudinal direction of the wheel arm (30). [10] Material handling vehicle with a quick-change load wheel unit, the material handling vehicle comprising a frame (12), a mast unit (16) connected to the frame (12), a pair of wheel arms (30) connected to the frame (12) and extending from a front of the vehicle, wherein each of the wheel arms (30) includes a mounting structure having a pair of laterally spaced bearing plates (136a, 136b) forming a load wheel opening (137) for receiving a quick-change load wheel unit (128), and a crossbeam (170) extending laterally across the load wheel opening (137), wherein the load wheel unit (128) comprises a first and a second lateral support element (142a, 142b) which are laterally spaced from each other, a pair of rollers (144,146) rotatably arranged between the first and second support members (142a,142b) to form a pair of load wheels, an axle (148,150) carrying each of the rollers (144,146) on the first and second lateral support elements (142a,142b), and a block element (164) extending between and connecting the first and second lateral support elements (142a, 142b), the lateral support elements being pivotable (166) relative to the block element (164), wherein the block member (164) has a lower surface (181) contacting and mating with an upper surface (168) of the crossbeam (170) to form a fixed connection between the block member (164) and the crossbeam (170) and thus with the material handling vehicle. [11] A material handling vehicle according to claim 10, including a fastening means (174) extending between the block member (164) and the crossbeam (170) for holding the block member in contact with the crossbeam. [12] A material handling tool according to claim 10, comprising a pivot opening (168a, 168b) formed in each lateral support member (142a, 142b) and including pivot ends extending on opposite sides of the block member (164) and engaging the pivot openings. [13] A method of installing a load wheel unit to a boom (30) of a material handling vehicle, the boom (30) having a boom housing (135) including a pair of laterally spaced bearing plates (136a, 136b) forming a load wheel opening (137) for receiving a load wheel unit (128), a crossbeam (170) extending laterally across the load wheel opening (137), the load wheel unit including at least two rollers (144, 146) supported on at least two axles between a pair of lateral support members (142a, 142b), and a connecting structure (162) having a block member (164) extending between the pair of lateral support members (142a, 142b), the method comprising positioning the load wheel unit (128) in the load wheel opening (137) from above, wherein the block element (164) is arranged above the crossbar (170), engaging at least one threaded fastener (174) between the block element (164) and the crossbeam (170), and Rotating the threaded fastener (174) thereby moving an upper surface (187) of the crossbeam (170) into engagement with a lower surface (187) of the block member (170), the orientation of the surfaces (187,181) of the crossbeam and the block member being related to the completed installation of the load wheel assembly to the boom on the material handling vehicle. [14] The method of claim 13, wherein rotation of the fastener (174) causes vertical movement of the boom (30) from a support surface (88), wherein the at least one roller (144,146) supports or holds the boom (30) spaced from the support surface (88) during vertical movement of the boom (30). [15] The method of claim 14, wherein two fasteners (174) are arranged laterally spaced from each other and engaged with the connecting structure (162) and the crossbeam (170), wherein rotating the fastener comprises alternately moving each of the fasteners to move the crossbeam (170) a distance toward the connecting structure (162). [16] The method of claim 13, including providing a unit holding tool (194) having a side member engagement structure (196) and, prior to positioning the load wheel unit in the load wheel opening, locating the side member engagement structure of the unit holding tool adjacent at least a portion of the side support members (142a, 142b) to engage the side support members with the axle (148, 150) and the connecting structure (162) to form a preassembled load wheel unit (207). [17] The method of claim 16, including positioning a lower portion of the pre-assembled load wheel unit (207) in the load wheel opening (137) and displacing the lateral support members (196a, 196b) downwardly into the load wheel opening (137) and away from the side plates of the unit holding tool (194). [18] The method of claim 16, wherein the abutment structure (196) comprises a pair of laterally spaced side plates (196a,196b).

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