GB2039836A

GB2039836A - Track Lines for Track-laying Vehicles

Info

Publication number: GB2039836A
Application number: GB7900800A
Authority: GB
Original assignee: Silentbloc Ltd
Current assignee: Silentbloc Ltd
Priority date: 1979-01-09
Filing date: 1979-01-09
Publication date: 1980-08-20

Abstract

Adjacent track links (10, 18) are connected by a joint including six rubber bearings (22), each having inner and outer layers (30, 24) of rubber, separated by a rigid steel sleeve (28). The six bearings (22) together occupy most of the width of the link (18); this gives good load- carrying capacity. By sharing the shearing movement between two layers of rubber, the fatigue life of the joint may be improved. <IMAGE>

Description

SPECIFICATION Track Links for Track-laying Vehicles This invention relates to track links for tracklaying vehicles, and is particularly concerned with the joints between adjacent links.

It is already known to use rubber-bushed joints to connect adjacent links of a track for a tracklaying vehicle; when the links pivot relative to one another, for example when the track passes around a sprocket, the pivoting movement is absorbed by shearing of the rubber. The rubber bushes are also placed under a radial load by any tension in the track, and this load results in a small relative movement of each link relative to its neighbour. It is important that the resulting increase in the length of the track should not be excessive, even when the track has been in use for a considerable period.

According to one aspect of the present invention, a track link for a track-laying vehicle is provided with an elastomeric joint for connection to an adjacent link, the elastomeric joint including at least two nested coaxial elastomeric sleeves each contained radially between rigid cylindrical surfaces.

With such an arrangement, the total radial thickness of the elastomeric sleeves can be made sufficient to absorb the relative pivoting movement of the track links, without the shear strain on the elastomer becoming excessive. At the same time, it will be appreciated that, since the radial flexibility of an elastomeric sleeve is roughly proportional to the inverse of the square of the radial thickness of the sleeve, a track link joint incorporating two nested elastomeric sleeves will be roughly twice as stiff against radial loads as a joint incorporating a single sleeve of twice the radial thickness.Also, and perhaps more importantly, it has been found that a joint incorporating two nested elastomeric sleeves survives much better under repeated pivoting movement than does a joint using only a single sleeve; specifically, a much larger number of cycles has to occur before stretching of a track using the joints becomes unacceptable.

In a preferred arrangement, the elastomeric sleeves occupy a major part of the width of the track link. In the remaining parts of the width of the link, connections may be made between a joint pin passing through the centre of the elastomeric sleeves and an adjacent track link.

These connections would be rigid connections, since the nested elastomeric sleeves can accommodate the whole of the pivotal movement; being rigid connections, they need not occupy much lateral space. Thus, by devoting most of the width of the track to the elastomeric sleeves, the load-carrying capacity of the joint can be maximised. It will be appreciated that, if an arrangement were used in which a joint pin was connected to both the adjacent track links by elastomeric sleeves, the radial thickness of these sleeves could be made no greater than in a track link embodying the present invention, but the load would be transferred from the joint pin to each of the links through elastomeric sleeves occupying only about half the width of the track. This would iimit the load-carrying capacity of the link.

The invention may be carried into practice in various ways, but one specific embodiment will now be described by way of example, with reference to the accompanying drawing, of which the single figure shows the joint between two links of a track of a track-laying vehicle, in sectional plan view (assuming that the links are both on a horizontal run of the track).

The link 10 on the right-hand side of the drawing has three lugs 12, of comparatively narrow axial extent, within which a closely fitting joint pin 14 is received, and retained in place by means of cross pins 16, one through each of the lugs 12. The link 18 on the left-hand side of the drawing has two sleeve portions 20 which surround the two parts of the joint pin 14 extending between the lugs 12. Tension loads in the track are transmitted between the two links through six rubber bearings 22 housed in the sleeve portions 20, three in each sleeve portion, around the joint pin 14. Each bearing 22 comprises an outer rubber sleeve 24, which is received in the annular space between an outer steel sleeve 26 and an intermediate steel sleeve 28, and an inner rubber sleeve 30 which is received in the annular space between the intermediate steel sleeve 28 and an inner steel sleeve 32.The outer steel sleeves 26 of the various rubber bearings 22 are an interference fit in the bore of the sleeve portions 20, while the inner steel sleeves 32 are a close fit on the joint pin 14; means (not shown) are provided to prevent rotation of the inner sleeves 32 about the joint pin 14.

The rubber sleeves 24 and 30 are, in this example, bonded to the steel sleeves 26, 28 and 32; however, it is alternatively possible for the rubber sleeves to be received under precompression between the sleeves 26, 28 and 32, so that the friction between the rubber and the steel is sufficient to prevent slipping between the rubber and steel.

Thus, when the two links 10 and 18 make a pivoting movement relative to one another, as for example when the track passes around a sprocket, the pivoting will be absorbed by circumferential shearing of the rubber sleeves 24 and 30. Since the amount of shearing is divided between the inner and outer rubber sleeves, the radial thickness of the rubber can be fairly small without the shear strain becoming excessive.This small thickness of rubber has advantages in keeping the deflection of the bearings 22 under a radially-directed force (i.e. tension in the track) to a minimum; since the radial flexibility of a single rubber sleeve is roughly proportional to the inverse of the square of the radial thickness of the rubber, it will be appreciated that two thin rubber sleeves in series are roughly twice as stiff under radial loading as a single rubber sleeve having twice the radial thickness. A further advantage resulting from the use of two radially thin rubber sleeves in series is connected with the torsional behaviour of the bearing; although there is not a great deal of difference in behaviour from a single thick rubber sleeve when the sleeves are new, it is found that the bearings using two thin rubber sleeves have a much longer fatigue life under repeated torsional movements than do bearings using a single thick rubber sleeve.

Claims

1. A track link for a track-laying vehicle, which link includes an elastomeric joint for connection to an adjacent track link, the joint including at least two nested coaxial elastomeric sleeves each contained radially between rigid cylindrical surfaces.

2. A link as claimed in Claim 1, in which the elastomeric sleeves occupy a major part of the width of the link.

3. A link as claimed in Claim 2, when connected to an adjacent link by means of a joint pin passing through the centre of the elastomeric sleeves, the joint pin having at least two rigid connections to the adjacent link, which connections occupy those parts of the width of the track link not occupied by the elastomeric sleeves.

4. A pair of track links for a track-laying vehicle, the links being connected by a joint substantially as herein described, with reference to the accompanying drawings.