The invention relates to a wheel frame which is mounted to a work machine. The invention relates, more specifically, to a wheel frame provided with at least one wheel pair in which the wheels are arranged to be able to follow a track. More specifically, the invention relates to a wheel frame which can be directly attached to the hydraulic linkage of the work machine at the front of the machine and directly to the hydraulic linkage of the work machine at the tail of the machine. The hydraulic linkages at the front of the machine and at the tail of the machine are arranged to exert a pressure downwards towards the track so that some of the weight of the machine can be transferred to the wheel frames at the front and rear. In a special embodiment, the wheel frame is provided with an equipment frame for releasable attachment of a piece of equipment. The equipment frame may be displaceable relative to the wheel frame.

There is a need to move work machines along a track of a railway. Such work machines may be self-propelling and do not form parts of a train set. To keep the work machine on the track, the machine is provided, at the front and rear, with wheels that are arranged to follow rails such as a railway track. To prevent the work machine from derailing off the track, it is known that some of the weight of the work machine is transferred to the track wheels. There is not more weight transferred than for the driving wheels of the work machine to have contact with the rails, so that the work machine can move along the track. It is also advantageous for any other wheels of the work machine to have contact with the rails as well, to get sufficient friction during braking. Such a work machine may be a tractor, a lorry, an excavator or some other suitable machine.

To maintain the correct spacing of the wheels so that they will each follow a respective rail, it is known that the wheels are attached to a wheel frame. The wheel frame is attached to the work machine. To enable the wheel frame to be lifted or lowered relative to the work machine, it is known that the wheel frame is attached to arms that are moved hydraulically. For some of the weight of the work machine to be transferred to the wheels, it is a prerequisite that the hydraulic system acts on the arms so that these can exert a pressure downwards towards the rails. It is known that work machines are provided with a special adapted hydraulic linkage for such use. Such work machines therefore have to be adapted for this purpose. It may be a drawback that the dedicated hydraulic system with arms and a wheel frame is in the way when the work machine is to be used for its usual purposes. It is also a drawback that the mounting and dismounting of a dedicated hydraulic system take time.

Further, it is known that tractors are provided with a quick-connector attached to the ordinary hydraulic linkage of the tractor. The quick-connector is used to releasably attach implements to the tractor. Such a quick-connector is available in several de- signs, and the implements must therefore be provided with an attachment which is complementary to the quick-connector chosen. The quick-connector is releasably attached to the draft links and top link of the hydraulic linkage, but in ordinary use, the quick-connector is not detached from the hydraulic linkage.

Tractors have a hydraulic linkage at the rear, and many tractors also have a hydraulic linkage at the front. A hydraulic linkage is usually a three-point linkage with two draft links at the bottom and one top link at the top. A hydraulic linkage may also be a four- point linkage with two draft links at the bottom and two top links at the top. A tractor may have a four-point linkage at the front at a three-point linkage at the rear. Other work machines may also be provided with three-point linkages and four-point linkag- es.

There are three-point linkages and four-point linkages that only can actively lift. There are also three-point linkages and four-point linkages that can actively press downwards.

A wheel frame which is provided with a modified quick-connector connection is known. This wheel frame can quickly be attached to a work machine which is provided with a hydraulic linkage connected to a modified quick-connector. The quick-connector must be modified because common quick-connectors are designed to lift, but not to press downwards. A drawback of this solution is that the hydraulic linkage of the work machine cannot be used to carry out other tasks when the wheel frame is attached. Equipping a tractor with separate, hydraulically operated arms at the rear is also known. Each arm is provided, at its free end, with a wheel which is arranged to follow a rail. Such a tractor can use its ordinary hydraulic linkage to operate equipment. The drawback is that the separate arms are impractical when the tractor is to carry out work outside the track. The draft link and the top link of a hydraulic linkage are available in several designs. A draft link and a top link provided with hooks at their free ends are advantageous for quick connection of equipment directly to the hydraulic linkage. The hook tip of the draft link is moved in under a supporting pin on the implement which is to be connected. The draft link is then lifted so that the supporting pin is resting on the bottom of the hook. Such a construction is well suited for lifting the implement, but not for pressing the implement downwards. The hook bottom will then no longer be in contact with the supporting pin.

The invention has for its object to remedy or reduce at least one of the drawbacks of the prior art or at least provide a useful alternative to the prior art.

The object is achieved through the features that are specified in the description below and in the claims that follow.

The invention relates, more specifically, to a wheel frame for positioning a work machine on a track, wherein the wheel frame is provided with at least one pair of wheels, in which the first wheel is designed to follow a first rail of the track and the second wheel is designed to follow an opposite second rail of the track, the first wheel is attached to the wheel frame with a first axle, and the second wheel is attached to the wheel frame with a second axle, the spacing of the wheel pair is fixed by the wheel frame which is fixed to the first axle and the second axle, and wherein the wheel frame is provided with a plurality of brackets for movable arms between the wheel frame and the work machine, and wherein the brackets comprise two draft-link brackets and at least one top-link bracket for a hydraulic linkage, the hydraulic linkage being attached to the work machine, and wherein a first rotatable mounting sleeve may enclose a portion of the first axle and a first draft-link bracket may be fixed to the first mounting sleeve, and a first tensioning bracket may be fixed to the first mounting sleeve, so that a length-adjustable tensioner may be attached between the mounting sleeve and a draft link.

The first axle and the second axle may be separate axles. The first axle and the second axle may be connected so that they form a continuous axle. The continuous axle may be a rigid axle.

A second rotatable mounting sleeve may enclose a portion of the second axle and a second draft-link bracket may be fixed to the second mounting sleeve, and a second tensioning bracket may be fixed to the second mounting sleeve, so that a length- adjustable tensioner may be attached between the mounting sleeve and a draft link. The length-adjustable tensioner may comprise a turnbuckle.

The hydraulic linkage may consist of a three-point linkage. The hydraulic linkage may consist of a four-point linkage. The hydraulic linkage may also be of other designs. The work machine may have a hydraulic linkage at the front and a hydraulic linkage at the rear.

The wheel frame may be provided with at least one equipment mounting.

The wheel frame may be provided with an equipment frame. The equipment frame may be displaceable relative to the wheel frame. The wheel frame may comprise at least one actuator attached to the wheel frame and to the equipment frame. The wheel frame may include at least one guide and the equipment frame may include at least one slide arranged to be moved along the guide. The wheel frame may include at least two guides and the equipment frame may include at least two slides.

The equipment frame may be provided with the at least one equipment mounting. The at least one equipment mounting may be a quick-connector mounting. The quick- connector mounting may be formed as an upward-facing tip which provides space for a power-transmission shaft at the underside of the quick-connector mounting. This allows the equipment to be connected to the power take-off of the work machine via the power-transmission shaft also when the equipment frame is in its lower position.

The wheels of the wheel frame may be provided with a brake. The brake may be a drum brake. The brake may be a disc brake. Each wheel may be provided with a brake.

In what follows, examples of preferred embodiments are described, which are visualized in the accompanying drawings, in which :

Figures 1A-B shows a side view of a work machine provided with wheel frames at the front and at the rear according to the invention, the work machine being positioned on rails and the wheels of the wheel frames being in contact with the rails, figure 1A showing an equipment frame at the front in its lower position and an equipment frame at the rear in its upper position, and figure IB showing the same as figure 1A, but with the front equip- ment frame in its upper position;

Figure 2 shows a rear view, on a larger scale than figures 1A-B, of the work machine with the equipment frame in its upper position; Figure 3 shows, on a smaller scale, the work machine and an attached piece of equipment on the rear equipment frame, the work machine being positioned on a flat surface;

Figure 4 shows the same, on the same scale, as figure 3, but the work machine is positioned on a track as in figures 1A-B;

Figure 5 shows a rear view, on another and larger scale, of the wheel frame with the equipment frame in a lower position;

Figure 6 shows on the same scale as figure 5, a side view of the same as in figure 5;

Figure 7 shows the same as figure 5, the equipment frame being in a lower position; and

Figure 8 shows a section along line B-B in figure 7.

In the figures, the reference numeral 1 indicates a wheel frame in accordance with the invention. The wheel frame 1 is releasably attached to a work machine 2 to guide the work machine 2 along a track 9. The wheel frame 2 is releasably attached to the hydraulic linkage 3 of the work machine 2. The work machine 2 is provided with a hydraulic linkage 3 at the front and a hydraulic linkage 3 at the rear. In the figures, a hydraulic linkage 3 of the three-point-linkage type is shown. In another embodiment, the hydraulic linkage 3 may be a four-point linkage. The front hydraulic linkage 3 of the work machine 2 may be of a different design from the rear hydraulic linkage 3 of the work machine.

The wheel frame 1 is shown in greater detail in figures 5 to 8. The wheel frame 1 is provided with at least one wheel pair 11. A first wheel 111 is attached to the wheel frame 1 with a first axle 17. A second wheel 113 is attached to the wheel frame 1 with a second axle 18. The first axle 17 may be connected to the second axle 18. The first axle 17 may be rigidly connected to the second axle 18 as shown in the figures. The wheel frame 1 is provided with a plurality of brackets 13 for movable arms 21. The movable arms 21 are part of the hydraulic linkage 3.

The wheel frame 1 further includes a guide 15 which is fixed to the axle 17, 18. In the figures, two guides 15 are shown. The guides 15 are provided with a tie bar 19 in their upper portions.

The first axle 17 is provided with a first mounting sleeve 6, 61 in a portion by the first wheel 111. The mounting sleeve 6 houses the first axle 17, and the mounting sleeve 6 is rotatable around the first axle 17. In its outer jacket surface, the first mounting sleeve 61 is provided with a bracket 13 in the form of a draft-link bracket 131 and a first tensioning bracket 63. The draft-link bracket 131 and the tensioning bracket 63 may be in approximately diagonally opposite positions on the mounting sleeve 6. The second axle 18 is provided with a second mounting sleeve 6, 62 in a portion by the second wheel 113. The mounting sleeve 6 houses the second axle 18, and the mounting sleeve 6 is rotatable around the second axle 18. In its outer jacket surface, the second mounting sleeve 62 is provided with a bracket 13 in the form of a second draft-link bracket 132 and a second tensioning bracket 64. The draft-link bracket 132 and the tensioning bracket 64 may be in approximately diagonally opposite positions on the mounting sleeve 6.

The tie bar 19 is provided with a bracket 13 in the form of a top-link bracket 133. In the figures, one top-link bracket 133 designed for a hydraulic linkage 3 of the three- point-linkage type is shown. The top-link bracket 19 may be provided with two top- link brackets 133 for a hydraulic linkage 3 of the four-point-linkage type.

The wheel frame 1 is releasably and directly attached to the hydraulic linkage 3 of the work machine 2 as is shown in figure 2. A draft link 211 is attached to the first draft- link bracket 131. A draft link 211 is attached to the second draft-link bracket 132. A top link 213 is attached to the top-link bracket 133. Figure 2 shows the wheel frame 1 attached to the tail of the work machine 2.

Figure 8 shows that, on its underside, the draft link 211 is provided with an attachment lug 66. Figure 8 also shows a hook 23 on the free end of the draft link 211. The hook 23 has a hook tip 24, a hook bottom 25 and a hook underside 26. The hook bottom 25 has been moved in under a supporting pin 27 by the hook tip 24 having been inserted first into the draft-link bracket 132 between the supporting pin 27 and the second mounting sleeve 62.

A length-adjustable tensioner 65 is attached, in one end portion, to the second tensioning bracket 64 and is attached, in its other end portion, to the attachment lug 66. The length-adjustable tensioner may consist of a turnbuckle 65' . The length- adjustable tensioner 65, 65' is shortened. Thereby the axle 18 is rotated around the supporting pin 27 until the second mounting sleeve 62 comes into abutment against the hook underside 26 of the hook 23. A firm contact is achieved between the draft link 211 and the second mounting sleeve 62 and thereby with the axle 18. A downward pressure from the draft link 211 is thus transmitted directly to the wheel 113. Correspondingly, the opposite draft link 211 is provided with an attachment lug 66 (not shown) and the wheel frame 1 is attached to the opposite draft link 211 in the same way.

Figures 1A-B, 3 and 4 show that the wheel frame 1 is attached to the front of the work 5 machine 2 in a manner corresponding to that at the tail of the work machine 2.

The wheel frame 1 may be provided with an equipment frame 4. The equipment frame 4 may be displaceable relative to the wheel frame 1. The equipment frame 4 may be provided with a plurality of equipment mountings 41. The equipment mounting 41 may be a quick-connector mounting 411. A piece of equipment 8 may be releasably i o attached to the equipment frame 4 as shown in figures 3 and 4. The equipment 8 is shown as an implement case 81. The equipment 8 may be connected to the power take-off (not shown) of the work machine 2.

The quick-connector mounting 411 is formed as an upward-facing tip which provides space for a power-transmission shaft (not shown) at the underside of the quick- 15 connector mounting 411. This allows the equipment 8 to be connected to the power take-off of the work machine 2 via the power-transmission shaft also when the equipment frame 4 is in its lower position.

The wheel frame 1 may be provided with an actuator 5 for displacing the equipment frame 4. It may be advantageous for the wheel frame to be provided with two actua- 20 tors 5 as shown in figures 2, 5-7. The actuator 5 may be of a known type such as a hydraulic cylinder. The actuator may also be a rotating screw, a pitch rack or an electric actuator. The actuator 5 may be connected to the hydraulic system or electric system of the work machine 2 in the usual way. The actuator 5 may be controlled from the work place of the work machine 2.

25 In one end portion, the actuator 5 is attached to the axle 17, 18. In its other end portion, the actuator 5 is attached to an actuator bracket 51, see figures 5 and 7. The actuator bracket 51 is fixed to the equipment frame 4. The equipment frame 4 is further provided with a slide 45 which follows the guide 15. In the figures, the slide 45 is shown as a sleeve surrounding the guide 15. The slide 45 may also be of other de-

30 signs. In the figures, two guides 15 and two slides 45 are shown. The number of

guides 15 and slides 45 may be one or more than two.

The wheel frame 1 can be releasably connected to a hydraulic linkage 3 of a standard type. If necessary, the hydraulic linkage 3 must be modified to be able to press downwards. The work machine 2 needs no further adaptations. The wheel frame 1 being disconnected, the work machine 2 can be used in the usual way and without the drawbacks of extra adaptations.

The wheel frame 1 with the equipment frame 4 has the advantage of enabling equipment 8 to be lifted and lowered independently of the hydraulic linkage of the work machine 2. This is shown in figures 1A-B, 4, 5 and 7.

When the work machine 2 is driving on a road 99 or some other flat surface as shown in figure 3, the wheel frames 1 at the front and rear are raised up. When driving on a track 9 as shown in figures 1A-B, 2 and 4, the wheel frames 1 have been lowered so that the wheels 111, 113 are in contact with the rails 91, 93. The wheel frames 1 at the front and rear are pressed against the rails 91, 93 so that some of the weight of the work machine 2 is transferred to the wheels 111, 113 at the front and rear.

The wheel frame 1 has the advantage of equipment 8 that is secured to the wheel frame 1 is resting on the wheel frame 1. The wheel frame 1 is thus carrying all of the weight of the equipment 8 and some of the weight of the work machine 2. The work machine 2 will constitute a counterweight to the equipment 8.

It should be noted that all the above-mentioned embodiments illustrate the invention, but do not limit it, and persons skilled in the art may construct many alternative embodiments without departing from the scope of the attached claims. In the claims, reference numbers in parentheses are not to be regarded as restrictive.

The use of the verb "to comprise" and its different forms does not exclude the presence of elements or steps that are not mentioned in the claims. The indefinite article "a" or "an" before an element does not exclude the presence of several such elements.

The fact that some features are indicated in mutually different dependent claims does not indicate that a combination of these features cannot be used with advantage.