Auxiliary wheel device for tractors and tractor systems

Description

TECHNICAL FIELD

[0001] The present invention relates to an auxiliary wheel device for tractors and a tractor system. STATE OF THE ART

[0002] Support and transport wheels for mounted reversible ploughs are state-of-the-art. Support wheels are usually mounted on the frame at the end of a plough and automatically swing from one working position to another during a plough turn. At the end of a field or during transport, such support wheels remain on the frame and are raised with the plough. On mounted reversible ploughs, support wheels serve to control the depth of the plough body during plowing. Transport wheels are particularly common on multi-furrow mounted reversible ploughs, supporting part of the weight of the raised multi-furrow mounted reversible plough during transport.

[0003] DE 7014464 discloses a swinging contact and transport wheel for multi-furrow three-point reversible plows. The swinging contact and transport wheel is mounted at the rear of the plow frame. The ploughing depth can be adjusted by adjusting the swinging contact and transport wheel relative to the plow frame. The swinging contact and transport wheel automatically changes to a new working position when the three-point reversible plow is lifted and turned by the tractor's hydraulic system. For road transport, the swinging contact and transport wheel can be locked in a transport position.

[0004] DE 2362151 discloses a support wheel attachment with a support wheel that is detachably attached to a plough frame by means of a mounting plate and supports the plough on the ground. The support wheel is pivotally mounted about an axis arranged on the frame. The pivoting range of the support wheel is limited to 180° by stops on the plough side. Furthermore, the support wheel attachment has a clamping device, which allows a height adjustment of the support wheel. Furthermore, the support wheel attachment has a support wheel fork that can rotate freely about a pivot axis. This free rotation is desirable for a transport position of the support wheel, in which the pivoting of the support wheel about the axis is disabled by means of a locking device.

[0005] Other support wheels attached to plough frames are known from EP 3166379, EP 2627162, EP 2408289, EP 1449417, EP 0986943, DE 29815053 and DE 4031504. TASK

[0006] The object of the invention is therefore to provide an improved auxiliary wheel device and in particular an improved auxiliary wheel device for tractors and tractor systems with heavy attachments. DISCLOSURE OF THE INVENTION

[0007] According to the invention, an auxiliary wheel device for tractors is proposed according to claim 1. The auxiliary wheel device according to the invention comprises, in particular, at least one first auxiliary wheel and a wheel suspension. The wheel suspension can have a first axis of rotation about which the first auxiliary wheel is rotatably mounted. The wheel suspension can have a second axis of rotation about which the first auxiliary wheel is steerably mounted. In particular, the auxiliary wheel device according to the invention comprises a fastening device for removably fastening it to the tractor.

[0008] A tractor generally refers to a motor-driven land-based towing vehicle, e.g., a tractor, used to pull wagons, trailers, low-loaders, semi-trailers, agricultural implements, ballasts, and other non-powered vehicles. A tractor with at least one attached wagon, trailer, low-loader, semi-trailer, agricultural implement, ballasts, or other non-powered vehicle is referred to below as a combination.

[0009] Tractors are generally characterized by various connection points or attachment points, also called trailer couplings, for pulling or driving agricultural implements. Agricultural implements include, for example, plows, harrows, cultivators, seed drills, rakes, mowers, etc. Attachment points include, for example, front and rear trailer couplings using bolts, drawbars, hitch hooks, piton-fix, ball-head couplings, three-point hydraulics, quick-coupling triangles, fifth wheel couplings, and / or coupling rails or towing brackets.

[0010] Attachments and ballasting can affect the driving characteristics of a tractor. In general, the permissible axle loads, the maximum permissible total weight and the tractor's tire load capacity must not be exceeded when attaching implements to the tractor when driving on the road. In particular, the front axle of the tractor should be loaded with at least 20% of the tractor's unladen weight in order to ensure sufficient steering effect of the front axle even with attachments attached to the rear. Exceeding this limit may be permissible in field use if a tractor manufacturer specifies higher technical axle loads or a higher technical total weight. Heavy attachments are particularly those which, when attached to the rear of the tractor in field use, for example a plough in a working position, relieve the load on the front axle to such an extent that less than 20% of the unladen weight rests on the front axle.Traditionally, in such cases, ballasting was arranged at the front of the tractor and / or the heavy attachments were equipped with a fixed, i.e. non-removable, supporting support wheel and / or transport wheel. At one end of the field, however, such a heavy attachment may have to be lifted in order to turn the tractor together with the attachment. In this case, however, a conventional support wheel can no longer fulfil its supporting function, precisely when maintaining the tractor's steerability is particularly important. The auxiliary wheel device according to the invention is preferably attached directly to the tractor, in particular to a rear of the tractor, so that it does not have to be lifted together with the heavy attachment, for example at one end of the field. Rather, the auxiliary wheel device according to the invention can support the front axle, i.e. load it with at least 20% of the tractor's unladen weight, so that the tractor's steerability is maintained.

[0011] Conventional transport wheels for heavy attachments do not normally have a steering axle but are unsteered, meaning that the heavy attachment must be towed to and from the field using an articulated trailer coupling, while the heavy attachment is typically attached to the three-point hydraulic linkage in the working position. This means that conventional heavy attachments require additional effort during transport. The second rotational axis of the auxiliary wheel device according to the invention makes it possible to transport the heavy attachment, in particular without having to switch to an articulated trailer coupling, but simply by lifting or unlifting the heavy attachment. The auxiliary wheel device according to the invention can passively steer the tractor when cornering, simultaneously relieving the rear axle of the towing vehicle and loading the front axle of the towing vehicle.

[0012] Conventional pendulum support wheels on mounted reversible plows usually swing abruptly from one working position to another during a plow turn. This creates sudden, high torques and forces on the trailer coupling and / or tractor hydraulics, which can cause wear or damage. The auxiliary wheel device according to the invention is essentially attached directly to the tractor, so that sudden swinging during the turn is particularly avoided.

[0013] According to a further embodiment, the fastening device can comprise a trailer hitch. Furthermore, it can be preferred for the fastening device to comprise a slide plate for attachment to a trailer hitch of the tractor. The design of the fastening device as a trailer hitch essentially has the advantage of universal compatibility with tractors from different manufacturers. The design as a slide plate for attachment to a trailer hitch or a slide guide of the tractor essentially enables the simultaneous use of other trailer hitches of the tractor. For example, the auxiliary wheel device according to the invention can be attached to the trailer hitch and, at the same time, a mounted reversible plough can be attached to the three-point hydraulics of the tractor. The slide plate can be mounted on the slide guide so that it can be height-adjustable, for example in order to individually adjust the auxiliary wheel device according to the invention to a tractor.The slide plate engages the slide guide in a form-fitting manner. The slide plate and the slide guide can be releasably connected to each other using one or more bolts or screw bolts.

[0014] According to a further embodiment, the wheel suspension can comprise a steering column that supports the first auxiliary wheel so that it can be steered about the second axis of rotation. Furthermore, the wheel suspension can comprise a steering axle, at the distal end of which the auxiliary wheel can be arranged so that it can rotate about the first axis of rotation. The steering axle engages the steering column at its proximal end so that it can rotate about the second axis of rotation. To dampen steering movements of the auxiliary wheel, the wheel suspension can further comprise a friction element that frictionally engages the steering axle. A helical tension spring is arranged, in particular, eccentrically at the proximal end and acting on the wheel suspension in order to preload the friction element against the steering axle.

[0015] It is further preferred that the wheel suspension essentially comprises at least one first rocker arm, also called a longitudinal control arm, which movably suspends the first auxiliary wheel. The rocker arm can be articulated at one end to the fastening device. At its other end, the rocker arm can be arranged on the steering column. In addition, the wheel suspension can comprise at least a second and / or third and / or fourth rocker arm, which movably suspend the first auxiliary wheel. The rockers can be articulated at one end to the fastening device at a distance from one another and connected to one another at their other ends and / or articulated via one or more struts. The fastening device, the rockers and / or the one or more struts can preferably form a closed kinematic chain.In particular, multiple rockers improve the transmission of forces, such as transverse forces, and torques from the first auxiliary wheel to the fastening device or to the tractor.

[0016] The wheel suspension further comprises an actuator for moving the first auxiliary wheel relative to a ground surface. The actuator comprises, in particular, a linear motor, a hydraulic cylinder, or the like. The hydraulic cylinder can be articulated at one end to the fastening device or to one end of the at least one rocker arm, and at its other end to another end of the second rocker arm, to a strut, or to the steering column. The hydraulic cylinder can raise or lower the first auxiliary wheel relative to the tractor or relative to the ground surface. The hydraulic cylinder is, in particular, controllable from the cab of the tractor. The contact pressure of the first auxiliary wheel relative to the ground surface can be adjusted by means of a pressure relief valve and / or a pressure accumulator for hydraulic fluid.

[0017] The first and second axes of rotation are preferably arranged relative to one another in such a way that they cause the first auxiliary wheel to caster. The term caster or caster distance is generally used to describe the component of a vector from a wheel contact point to a point of intersection of the steering axis or second axis of rotation through the road surface in the direction of an intersection line between the wheel center plane and the road surface. The wheel contact point is preferably located behind the point of intersection, viewed in the direction of travel, and is also referred to as positive caster, so that the first auxiliary wheel follows the second axis of rotation. The caster can generate a torque when cornering which counteracts this as a restoring torque. As a result, the auxiliary wheel device steers automatically back to a straight-ahead position. Caster generally improves straight-ahead stability of the first auxiliary wheel.

[0018] According to a further embodiment, the auxiliary wheel device may comprise a second auxiliary wheel which is arranged in particular at an acute angle to the first auxiliary wheel in order to effect a toe-in.

[0019] Furthermore, a tractor system according to claim 8 is provided, which in particular comprises a tractor and the auxiliary wheel device according to the invention. Advantageous developments of the invention are specified in the subclaims and described in the description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Embodiments of the invention are explained in more detail with reference to the drawings and the following description. They show: Figure 1A shows an embodiment of a perspective view of an auxiliary wheel device according to the invention, Figure 1B shows a sectional view of the embodiment of the auxiliary wheel device of Fig. 1A , Figure 2 shows an embodiment of a towing bracket according to the invention and Figure 3 shows an embodiment of a tractor system according to the invention. EMBODIMENTS OF THE INVENTION

[0021] In the Figur 1A An auxiliary wheel device 100 is shown. The auxiliary wheel device 100 comprises a first 102, a second auxiliary wheel 104, a wheel suspension 106 and a slide plate 108. The slide plate 108 serves for the removable attachment of the auxiliary wheel device 100 to a trailer bracket with slide guides (see Fig. 2 ), with the towing bracket mounted at the rear of a tractor. For attachment, the carriage plate 108 comprises four bolts 110 that engage in corresponding holes in the carriage guides.

[0022] The wheel suspension 106 further comprises a steering column 112 and a steering axle 114. The steering axle 114 engages the steering column 112 at one end, rotatable about a pivot axis 116. At another end of the steering axle 114, the auxiliary wheels 102, 104 are arranged on both sides, rotatable about a pivot axis 118.

[0023] The wheel suspension 106 also includes a first 120 and a second U-shaped swing arm 122. The first U-shaped swing arm 120 is pivotally connected to the carriage plate 108 at one end. The second U-shaped swing arm 122 is also pivotally connected to the carriage plate 108 at one end. The pivot points of the U-shaped swing arms 120, 122 on the carriage plate 108 are spaced apart from one another. The wheel suspension 106 further includes a V-shaped strut 124. The first U-shaped swing arm 120 is pivotally connected to one end of the V-shaped strut 124 at its other end. The second U-shaped swing arm 122 is pivotally connected to the other end of the V-shaped strut 124 at its other end. The slide plate 108, the two U-shaped rockers 120, 122 and the V-shaped strut 124 form a closed kinematic chain and resemble a parallelogram with joints at the corners.

[0024] A yoke-like strut 126 is arranged at the other end of the second U-shaped swing arm 122 and reinforces an open side of the U of the U-shaped swing arm 122. Two double-acting hydraulic cylinders 128, 130 are arranged on either side of the wheel suspension 106. First ends of the hydraulic cylinders 128, 130 are each hinged to either side of the first end of the first U-shaped swing arm 120. Other ends of the hydraulic cylinders 128, 130 are each hinged to the ends of the yoke-like strut 126. The hydraulic cylinders 128, 130 are arranged similar to a parallelogram diagonal. When the double-acting hydraulic cylinders 128, 130 retract, they displace the parallelogram or the wheel suspension such that the auxiliary wheels 102, 104 are lifted off a surface 136 (see Fig. 1B ) are raised. When the double-acting hydraulic cylinders 128, 130 extend, they move the parallelogram or the wheel suspension in such a way that the auxiliary wheels 102, 104 rest on the ground 136 (see Fig. 1B ) can be lowered.

[0025] Attachments and ballasting can affect the driving characteristics of the tractor. In general, the permissible axle loads, the maximum permissible total weight and the tire load capacity of the tractor must not be exceeded when attaching implements to the tractor when driving on the road. The front axle of the tractor should be loaded with at least 20% of the tractor's unladen weight in order to ensure sufficient steering effect of the front axle even with attachments attached to the rear. Exceeding this limit may be permissible in field use if a tractor manufacturer specifies higher technical axle loads or a higher technical total weight. Heavy attachments are particularly those which, when attached to the rear of the tractor in field use, for example a plough in a working position, relieve the load on the front axle to such an extent that less than 20% of the unladen weight rests on the front axle.Traditionally, in such cases, ballasting was arranged at the front of the tractor and / or the heavy attachments were equipped with a fixed, i.e. non-removable, supporting support wheel and / or transport wheel. At one end of the field, however, such a heavy attachment may have to be lifted in order to turn the tractor together with the attachment. In this case, however, a conventional support wheel can no longer fulfill its supporting function, precisely when maintaining the tractor's steerability is particularly important. The auxiliary wheel device 100 can be connected directly to the tractor, in particular fastened to a rear of the tractor, so that it does not have to be lifted together with the heavy attachment, for example at one end of the field. Rather, the auxiliary wheel device 100 can always support the front axle, i.e. load it with at least 20% of the tractor's unladen weight, so that the tractor's steerability is maintained.

[0026] Conventional transport wheels of heavy tractor attachments normally do not have a steering axle but are unsteered, meaning that the heavy attachment must be pulled on an articulated trailer coupling for transport to and from the field, while the heavy attachment is typically attached to the three-point hydraulic linkage in the working position. This means that conventional heavy attachments require additional effort during transport. The pivot axis 116 of the auxiliary wheel device 100 makes it possible to transport the heavy attachment, in particular without having to switch to an articulated trailer coupling, but simply by lifting or unlifting the heavy attachment. The auxiliary wheel device 100 passively steers when the tractor corners, simultaneously relieving the load on the rear axle of the tractor and loading the front axle of the towing vehicle.

[0027] Conventional pendulum support wheels on mounted reversible plows usually swing abruptly from one working position to another during a plow turn. This creates sudden, high torques and forces on the trailer coupling and / or tractor hydraulics, which can cause wear or damage. The auxiliary wheel device 100 can be attached directly to the tractor, preventing sudden swinging during the turn.

[0028] According to a further embodiment, the rotational axis 116 and the rotational axis 118 are arranged relative to one another in such a way that they cause a caster of the auxiliary wheels 102, 104. The caster or caster distance is the component of a vector from a wheel contact point to a point where the rotational axis 116 intersects the ground 136 (see Fig. 1B ) in the direction of a line of intersection between the wheel center plane and the ground 136 (see Fig. 1B ). The wheel contact point is preferably located behind the intersection point, also referred to as positive caster, as seen in the direction of travel, so that the auxiliary wheels 102, 104 trail the rotational axis 116. This caster can generate a torque when cornering that counteracts this restoring torque. As a result, the auxiliary wheel device 100 automatically steers back to approximately a straight-ahead position. Caster generally improves the straight-ahead stability of the auxiliary wheels 102, 104.

[0029] According to a further embodiment, the auxiliary wheel 102 is arranged at an acute angle to the auxiliary wheel 104 to effect toe-in. The acute angle is, for example, in a range of 1-20°, with the second auxiliary wheel 104 having a further axis of rotation arranged at a correspondingly obtuse angle to the axis of rotation 118.

[0030] in the Figur 1B A sectional view of the auxiliary wheel device 100 is shown, with the section passing through the rotation axis 116 and the carriage plate 106, bisecting the auxiliary wheel device 100. To dampen a steering movement of the auxiliary wheels 102, 104, the wheel suspension 106 includes a friction element 132 that frictionally engages the steering axle 114. A coil tension spring 134 is arranged eccentrically at one end of the steering axle 114 and engages the wheel suspension 106 to preload the friction element 132 against the steering axle 114.

[0031] In the Figur 2 A trailer hitch 200 is shown. The trailer hitch has two parallel slide guides 202, each with a plurality of holes 204. A height-adjustable slide plate is mountable in the slide guides 202 to individually adjust an auxiliary wheel device to a tractor. The slide plate engages positively in the slide guides 202. The slide plate and the slide guides 202 can be releasably connected to one another using one or more bolts or screw bolts. The trailer hitch 200 is welded or bolted to the tractor at the rear.

[0032] In the Figur 3A towing vehicle system 300 is shown. The towing vehicle system 300 includes a tractor 302, the auxiliary wheel device 100, and a heavy attachment 304 attached to a three-point hydraulic linkage 306 of the tractor 302. The heavy attachment 304 is shown in a raised or transport state. The attachment 304 is so heavy that it would relieve a front axle of the tractor 300 to such an extent that the tractor 302 would no longer have sufficient steering capability. The auxiliary wheel device 100 is lowered onto a base 308 and supports the front axle in such a way that the steering capability of the tractor 302 is restored. LIST OF REFERENCE SYMBOLS

[0033] 100Auxiliary wheel device 102First auxiliary wheel 104Second auxiliary wheel 106Wheel suspension 108Slide plate 110Bolt 112Steering column 114Steering axle 116Pivot axle 118Pivot axle 120First U-shaped swing arm 122Second U-shaped swing arm 124V-shaped strut 126Yoke-type strut 128Double-acting hydraulic cylinder 130Double-acting hydraulic cylinder 132Friction element 134Coil tension spring 136Subsoil 200Towing bracket 202Slide guide 204Bores 300Tractor system 302Tractor 304Heavy attachment 306Three-point hydraulics

Claims

1. An auxiliary wheel apparatus (100) configured for tractors (302) with: at least one first auxiliary wheel (102, 104) and a wheel suspension (106), wherein the wheel suspension (106) has a first rotating axis (118) about which the first auxiliary wheel (102, 104) is mounted for rotation, and wherein the wheel suspension (106) has a second rotating axis (116) about which the first auxiliary wheel (102, 104) is mounted in a steerable manner; and a fastening apparatus (108) arranged for removable fastening to the tractor (302), characterized in that the wheel suspension (106) comprises an actuator (128, 130) configured to move the first auxiliary wheel (102, 104) with respect to a ground in the mounted state of the auxiliary wheel apparatus (100).

2. The auxiliary wheel (100) apparatus according to claim 1, characterized in that the fastening apparatus (108) comprises a hitch apparatus (108).

3. The auxiliary wheel apparatus (100) according to claim 1 or 2, characterized in that the fastening apparatus (108) comprises a carriage plate (108) for fastening to a hitch bracket (200) of the tractor (302).

4. The auxiliary wheel apparatus (100) according to one of the preceding claims, characterized in that the wheel suspension (106) comprises a steering column (112), which supports the first auxiliary wheel (102, 104) in a steerable manner about the second rotating axis (116).

5. The auxiliary wheel apparatus (100) according to one of the preceding claims, characterized in that the wheel suspension (106) comprises at least one first swing arm (120, 122), which movably suspends the first auxiliary wheel (102, 104).

6. The auxiliary wheel apparatus (100) according to one of the preceding claims, characterized in that the first (118) and second rotating axes (116) are arranged relative to one another in such a way that they cause a trailing effect of the first auxiliary wheel (102, 104).

7. The auxiliary wheel apparatus (100) according to one of the preceding claims, characterized in that the auxiliary wheel apparatus (104) has a second auxiliary wheel (104), which is arranged at an acute angle to the first auxiliary wheel (102) in order to create a toe-in effect.

8. A tractor system (300) with a tractor (302) and an auxiliary wheel apparatus (100) according to one of the preceding claims.