GB2066187A

GB2066187A - Apparatus for removing and fitting a running pad of a track member of a crawler track

Info

Publication number: GB2066187A
Application number: GB8041306A
Authority: GB
Original assignee: Neuweg Fertigung GmbH
Current assignee: Neuweg Fertigung GmbH
Priority date: 1979-12-24
Filing date: 1980-12-23
Publication date: 1981-07-08
Also published as: FR2472442B1; GB2066187B; DE2952396A1; FR2472442A1

Abstract

Apparatus for pushing the running pad out of and into the shaped guide means of a track member of a vehicle crawler track, wherein, in the inserted condition, the running pad 24 is secured in position in the main body portion 25 of the track member by way of a securing tongue member 33 which is disposed in its edge region and which is let into the elastic profile of the running pad and which can be pressed away from its pad-securing position, which apparatus comprises a pressure fluid- actuated piston-cylinder unit 1, the free end of the piston rod 3 and both ends of the cylinder 2 being provided with downwardly directed (in use) abutments 4, 5, 6 for bearing against the running pad 24 and for bracing against the main body portion 25 respectively; and a second or auxiliary piston- cylinder unit 13 for releasing or pressing away the securing tongue member 33 of the running pad 24, the second unit 13 being connected with the main piston-cylinder unit 1 at one end with its axis parallel thereto. <IMAGE>

Description

SPECIFICATION Apparatus for removing and fitting a running pad of a track member of a crawler track The invention relates to apparatus for pushing the running pad out of and into the shaped guide means of a preferably two-part track member of a crawler track of vehicle, for example armoured vehicle, wherein, in the inserted condition, the running pads are secured in position in the main body portion of the track member by way of a securing tongue member which is disposed at the edge and which is let into the elastic profile of each running pad and which can be pressed away.

It is known for crawler tracks to be provided with running pads for the purposes of protecting the road surface. In this arrangement, the running pads are inserted into shaped guide means of the individual main body portions of each track member, and secured in position in the main body portion, so that they cannot be displaced laterally, by way of securing tongue members provided in the running pads.

For the purposes of replacing running pads, for example due to wear thereof, the securing tongue members are pressed away by driving in tapered pins, and then the pads are pressed or driven out of the guide means by means of a crobwar or a sledge hammer. However, replacing pads in this way involves a very great deal of work and is very highly labour-intensive.

Consequently, the present invention is based on the problem of providing an apparatus of the kind set forth hereinbefore, which can be operated by a single person and which permits running pads to be replaced in a short time.

According to the invention, there is provided a pressure fluid-actuated piston-cylinder unit, wherein the free end of the piston rod and both ends of the cylinder are provided with downwardly directed abutments for bearing against the running pad and for bracing against the main body portion respectively, and wherein associated with the pistoncylinder unit at one end, by way of a connecting arm means, with its axis parallel thereto, in a second auxiliary piston-cylinder unit for releasing or pressing away the securing tongue member of the running pad. In this arrangement, the hydraulic piston-cylinder unit is double-acting. In accordance with a further feature of the invention, the abutment on the piston rod is in the form of a lever which at its free end carries a pressure member which extends parallel to the piston rod.A further abutment is formed as a ring which engages around the cylinder at one end and which has a collar extending normal to the longitudinal axis of the cylinder. In a structurally simple form, the other abutment comprises a connecting arm means which has two bores which extend parallel to each other, with one end of the cylinder being mounted in one bore and the cylinder of the hydraulic auxiliary piston-cylinder unit being mounted in the other bore.

A preferred feature of the invention is that the auxiliary piston-cylinder unit has two pressure bars which are fixedly connected thereto and which extend parallel to each other and which serve for pushing the running pad into place, wherein, at its end which projects out of the cylinder, the piston rod has an inclined contact surface for releasing the securing tongue member and wherein, in the nonactuated condition of the auxiliary piston-cylinder unit, the pressure bars project beyond the contact surface. In this case, the auxiliary piston-cylinder unit is single-acting as it acts only in one direction, namely for pressing away the securing tongue member of the running pad, before the running pad is pushed from the main portion.In order now to ensure that the securing tongue member is actually pressed away or over-pressed by the contact surface before the actual operation of pushing out the running pad begins, the cylinder chamber has a lateral outlet port which is in communication with the cylinder chamber of the piston-cylinder unit by way of a through bore which is provided in the connecting arm means. This bore is so arranged that it is closed by the piston, when the auxiliary piston-cylinder unit is in a pressure-less condition.

However, because the auxiliary piston-cylinder unit is not actuated when a running pad is being fitted onto a main body portion and therefore the bore in the cylinder wall of the auxiliary piston-cylinder unit is closed by the piston, thereof, care must be taken to ensure that the oil which is displaced upon retraction of the piston-cylinder unit can also be discharged.

For this purpose, the connecting arm means has an oil connection which opens into the through bore. In this arrangement, the oil connection is provided with a return conduit which opens into the tank conduit, by way of an interposed non-return valve. Desirably, a multi-way valve is used for switching the apparatus according to the invention, the valve having a pump and a tank connection and a respective connection for the oil connection of the hydraulic piston-cylinder unit and a connection for the conduit which leads to the annular chamber of the pistoncylinder unit.It is desirable for the design of the apparatus according to the invention to be such that, during retraction movement of the piston rod of the piston-cylinder unit for the purposes of fitting a running pad, the oil flows to the tank solely by way of the oil connection in the connecting arm means, by-passing the auxiliary piston-cylinder unit, and, during extension movement of the piston rod for removing a running pad, the oil flows from the cylinder chamber of the auxiliary piston-cylinder unit into the cylinder chamber of the piston-cylinder unit by way of the bore, only after extension of the piston rod and after the securing tongue member has been lifted by the inclined contact surface.It is further proposed that, during extension movement of the piston rod, the oil flows to the tank solely by way of the conduit which is connected to the annular chamber of the piston-cylinder unit.

An embodiment of the invention will now be described in greater detail by way of example with reference to the accompanying diagrammatic drawings, in which: Figure 1 shows a side view of an apparatus according to the invention, Figure 2 shows a partly sectional view of the apparatus of Figure 1, Figure 3 shows a view in section taken along line Ill-Ill in Figure 1, Figure 4 shows a view in section taken along line IV-IV in Figure 2, and Figure 5 shows a circuit diagram.

Reference numeral 1 denotes a double-acting hydraulic piston-cylinder unit in which abutments 4, 5 and 6 are fitted both on the two ends of the cylinder 2 and also on the end of the piston rod 3, which projects from the cylinder. In the arrangement shown the abutment 4 comprises a bent lever 7 which is screwed to the piston rod 3 and which is proivded at its free end with a pressure member 8 mounted parallel to the piston rod 3. The abutment 5 comprises a ring 9 which is fixedly fitted on the cylinder 3 and which has a downwardly facing collar or bracket 10. Finally, the third abutment, the abutment 6, comprises a connecting arm means 11 in which there are two bores. The bores are disposed parallel to each other and one receives one end of the cylinder 2 and the other receives the cylinder 12 of a hydraulic auxiliary piston-cylinder unit 13.The cylinder chamber 14 of the cylinder 2 and the cylinder chamber 15 of the cylinder 12 are in communication with each other by way of a bore 16 in the connecting arm means 11, while the connecting arm means 11 also has an oil connection 17 for the bore 16. As can be seen best from Figure 2, the auxiliary piston-cylinder unit 13 is single-acting and therefore has only one oil connection 18. In this arrangement, the piston 19 is held in the basic position by the spring 20 and, in that position, closes the bore 16. In Figure 2 of course, the piston 19 is shown in the extended position in which the bore 16 is in communication with the cylinder chamber 15 and the oil can flow across into the cylinder chamber 14 of the piston-cylinder unit 1.As can also be seen from Figures 1 to 3, at its forward end which projects out of the cylinder 12, the piston rod 21 has an inclined contact surface 22. In the retracted condition (Figures 1 and 3), the contact surface 22 is disposed behind two pressure bars 23 which are welded to the connecting arm means 11 on the sides thereof, while in the extended position the surface 22 projects forwardly beyond the pressure bars 23 (see Figure 3).

If now a running pad 24 is to be fitted onto a main body portion 25 of a two-part track member 26 of a crawler track, the running pad 24 is first put into the position shown in Figure 3, and then the pistoncylinder unit 1 is fitted in such a way that the pressure member 8 bears against the main body portion 25 and the pressure bars 23 bear against one edge of the running pad 24. The valve 26 is then actuated so that the oil delivered by the pump 28 passes by way of the throttle non-return valve 29 into the annular chamber 30 of the cylinder 2 whereby the cylinder 2 is moved in the direction indicated by arrow A.During this movement, the pressure bars 23 and the pressure member 8 move towards each other and in so doing push the running pad 24 into the shaped guide means 32 of the main body portion 25 until the securing tongue member 33 which is provided at an edge of the running pad 24 and which is fixedly connected to the running pad comes to lie and engages behind the collar 34 of the recess 35. The running pad 24 is then secured to the main body portion 25 so that it cannot be pushed out laterally, especially as the end of the running pad 24 which is remote from the securing tongue member 33 has been pushed against the abutment 36 of the main body portion 25.In this operation, the oil which is displaced from the cylinder chamber 14 during the pushing movement of the piston 31 flows back into the tank 39 by way of the oil connection 17, the throttle non-return valve 37 and the tank line 38.

Return flow by way of the conduit 18 was not possible because the bore 16 was closed by the piston 19.

If a running pad 24 is to be pushed out of a main body portion 25 (see Figure 2), the hydraulic pistoncylinder unit is moved into such a position that the back of the lever 7 bears against the main body portion 40 which is adjacent to the main body portion 25, and the inclined contact surface 22 is disposed in front of the aperture in the collar 34 (this position is not shown). The valve 27 is then actuated in such a way that the oil flow delivered by the pump 28 passes by way of the throttle non-return valve 37 and the oil connection 18 into the cylinder chamber 15 of the auxiliary piston-cylinder unit 13 and moves the piston 19 in the direction indicated by arrow B, in which case the inclined contact surface 22 pushes under the securing tongue member 33 and lifts it out of the recess 35.During this movement, the piston 19 has opened the bore 16 (the position shown in Figure 2) so that the further flow of oil delivered passes into the cylinder chamber 14 and the cylinder 2 is displaced. When this occurs, the collar 10 bears against the running pad 24 which is to be pushed out, and presses it out of the guide means 32 of the main body portion 25, in the direction indicated by arrow C. The securing tongue member remains lifted by the contact surface 22 so that it cannot come to bear against the collar 34 from the interior, and impede the ejection movement. The oil which is displaced by the piston during the ejection operation flowed back into the tank by way of the line 41, the throttle valve 29 and the tank line 38.

In order to avoid over-pressure both during the operation of fitting a running pad and also during the operation of removing a running pad, a so-called by-pass line is branched from the pump line 42 and leads to the tank 39, with a pressure restricting valve 43 being incorporated in the by-pass line.

The pump 28 may be operated by means of an electric motor which is driven by the current from the battery of the crawlertrackvehicle. It will be appreciated that a separate internal combustion engine may also be used.

Claims

1. Apparatus for pushing the running pad out of and into the shaped guide means of a track member of a vehicle crawler track, wherein, in the inserted condition, the running pad is secured in postion in the main body position of the track member by way of a securing tongue member which is disposed in its edge region and which is let into the elastic profile of the running pad and which can be pressed away from its pad-securing position, which apparatus comprises a pressure fluid-actuated piston-cylinder unit, the free end of the piston rod and both ends of the cylinder being provided with downwardly directed (in use) abutments for bearing against the running pad and for bracing against the main body portion respectively; and a second or auxiliary piston-cylinder unit for releasing or pressing away the securing tongue member of the running pad, the second unit being connected with the main pistoncylinder unit at one end with its axis parallel thereto.

2. Apparatus according to claim 1, wherein the main piston-cylinder unit is double-acting.

3. Apparatus according to claim 1 or 2, wherein the abutment on the piston rod is formed as a lever which at its free end carries a pressure member which extends parallel to the piston rod.

4. Apparatus according to any one of claims 1 to 3 wherein the cylinder abutment at the piston rod end is in the form of a ring which engages around the cylinder and which has a bracket extending normal to the longitudinal axis of the cylinder.

5. Apparatus according to any one of claims 1 to 4 wherein the cylinder abutment at the closed end comprises a connecting arm means which has two bores which extend parallel to each other, an end of the cylinder being mounted in one bore and the cylinder of the hydraulic auxiliary piston-cylinder unit being mounted in the other bore.

6. Apparatus according to any one of claims 1 to 5 wherein the auxiliary piston-cylinder unit has pressure bars which are fixedly connected thereto and which extend parallel to each other, for pushing a running pad into place; at its end which projects out of the cylinder, the piston rod has an inclined contact surface for releasing the securing tongue member; and in the non-actuated condition of the auxiliary piston-cylinder unit, the pressure bars project beyond the contact surface.

7. Apparatus according to any one of claims 1 to 6 wherein the auxiliary piston-cylinder unit is singleacting.

8. Apparatus according to any one of claims 1 to 7 wherein the auxiliary cylinder member has a lateral outlet port which communicates with the main cylinder chamber of the piston-cylinder unit by way of a through bore provided in the connecting arm means.

9. Apparatus according to any one of claims 1 to 8 wherein when the auxiliary piston-cylinder unit is in a pressure-less condition, said port is closed by the piston.

10. Apparatus according to any one of claims 1 to 9 wherein the connecting arm means has an oil connection which opens into the through bore.

11. Apparatus according to any one of claims 1 to 10 wherein the oil connection is connected two a return conduit which opens into a conduit by way of a interposed non-return valve.

12. Apparatus according to any one of claims 1 to 11 wherein there is provided a multi-way valve which has a pump and a tank connection, and a respective connection for the oil connection of the auxiliary piston-cylinder unit and for the conduit which leads to the annular chamber of the pistoncylinder unit.

13. Apparatus according to claims 11 or 12 wherein during retraction movement of the piston rod of the main piston-cylinder unit for the purposes of fitting a running pad in position, the oil flows solely by way of the oil connection to the tank, by-passing the auxiliary piston-cylinder unit.

14. Apparatus according to any one of claims 1 to 13 wherein during extension movement of the piston rod for pushing a running pad out, the oil passes from the cylinder chamber of the pistoncylinder unit into the cylinder chamber of the piston-cylinder unit by way of the bore only after extension of the piston rod and after the securing tongue member has been lifted by the inclined contact surface.

15. Apparatus according to any one of claims 1 to 14 wherein during extension movement of the piston rod, the oil flows solely by way of the conduit to the tank.

16. Apparatus for pushing the running pad out of and into the shaped guide means of a track member of a vehicle crawler track, substantially as hereinbefore described with reference to the accompanying drawings.