GB2152885A - Endless track for vehicle - Google Patents

Abstract

An endless track for a light tank or armoured personnel carrier includes a plurality of interconnected molded flexible track sections (14). Each track section (14) has embedded therein cables (26) passing through cross bars (24) and connected at their ends to attachment bars. The attachment bars of adjacent track sections are interconnected by pins 42. Each track section has road contacting portions 20, traction ribs 16, and openings for receiving sprocket teeth. <IMAGE>

Description

SPECIFICATION Endless vehicle tracks Endless tank tracks have taken a wide variety of different forms. Some such tracks are described in patents to Russ 3,582,154; Chaumont 3,883,191 and Pilliod et al 4,351,380. Links for endless traction belts are disclosed in a patent to Kubaugh 2,234,927.

A military armored personnel carrier is presently being used with a 15 inch wide link type track incorporating rubber blocks on metal links connected with rubber bushings on a hex-through bolt.

In accordance with the present invention, an endless track, e.g. for light tank or carrier, is formed by a plurality of interconnected track sections each having a plurality of cross bars with cable lengths extending through the cross bars. The ends of the cables are connected to attachment members to permit the track sections to be interconnected. The cross bars, cables and attachment elements are bonded into a homogeneous section by cast elastomer (e.g. polyurethane). The invention resides in the individual track sections and in the endless track made up therefrom.

Preferred embodiments of the invention are described below, by way of example only, in conjunction with the accompanying drawings, in which: Figure 1 is a side view of a typical tank which may use the type of tank tracks built in accordance with the present invention; Figure 2 is an isometric view of the tread side of a track section, partly in cross section, in accordance with the present invention; Figure 3 is an isometric view of a portion of some of the interior elements making up the track section in accordance with the present invention; Figure 4 is a cross-sectional view, taken along lines 4-4 of Figure 2; Figure 5 is an isometric view of the road wheel side of a track section, in accordance with the present invention; Figure 6 is a cross-sectional view, taken along lines 6--6 of Figure 1;; Figure 7 is a cross-sectional view taken along lines 7-7 of Figure 1; and Figure 8 is an isometric view, partly broken away, of some of the interior parts of a track illustrating another type of connection, in accordance with the present invention.

Referring to Figure 1, a tank 10 includes an endless track 12. In the particular embodiment described, the track consists of six identical track sections being approximately 67.8 in. (172 cm) long and 3 in. (7.6 cm) deep forming an effectively continuous band on each side of the tank 10.

The present invention is directed towards the sections or segments forming the continuous track and will be described in connection with the subsequent Figures. One section of the endless track is illustrated by a section 14 in Figures 2 and 5. The track section comprises a molded urethane body, or other suitable elastomeric material, having fabri cated steel and stainless parts embedded therein.

Figure 2 illustrates the tread side of the track section. Figure 5 illustrates the road wheel side of the track section.

Referring to Figure 2, the track section 14 in cludes a plurality of traction ribs 16, cast sprocket holes 18 and road contact portions 20. Referring to Figure 5, the road wheel side of track section 14 includes a plurality of track guides 22, with the sprocket holes 18 also being illustrated.

Referring to Figure 3, the various elements embedded in the urethane casting are illustrated. A plurality of rectangular tubular cross bars 24 are provided. In the embodiment illustrated, each track section 14 consists of 10 such cross bars 24.

A plurality of cables 26 pass through openings in the cross bars 24. In the embodiment illustrated, the cables 26 may be made of steel and be eight in number. Attachment plates 28 including means therein for receiving the cables 26 are disposed at each end of the track section. The various cross bars, steel cables and attachment bars are bonded into a homogeneous element by cast urethane or other materials having similar properties.

The track section 14 has two cast sprocket holes 18 between each cross bar 24 and between the longitudinal cable 26 to accept the driving sprocket, generally located within the tank vehicle tread skirts. The road wheels, inside the tank vehicle tread skirts, are aligned on the track 14 by guides 22 welded to the cross bars 24 and attachment bars 38.

The road contact portions 20 are directly under the road wheel line of contact and has a virtually continuous contact with the road. The cross-section has variations that accommodate the passing of cross bars with no change in total tread spring rate thereby eliminating the link spacing frequency vibration characteristic of the link and pin type treads. The urethane material under the road wheels has a high surface to volume ratio to allow dissipation of heat.

The space from the road wheel contact to the edge of the treads include the traction ribs 16 of a space link track configuration that are slightly lower in height than the road contact portion.

Therefore, no contact is made when operating on smooth surfaces thereby eliminating objectionable noise and vibration. At the same time, when the vehicle is operating in soft terrain, the space link traction ribs 16 make contact with the soil and provide maximum soil shear area for maximum traction. Since the track sections are molded of urethane, variations of tread pattern can be easily made to optimize performance during the operation of the tank.

When the plurality of track sections 14 are joined together to form a complete track 12 for one side of the vehicle, the attachment points blend into the continuity of the individual track sections so that the action of the attachment points under the road wheels and around the side sprockets and idle wheel is smooth and does not disturb drive or suspension elements.

As illustrated in Figure 3, the cables 26 terminate in swage fittings 30 secured by tapered sprockets 32 in a hinged type replacement bar 34. The attachment bars 36 also include swage fittings connected to the ends of the cables 26.

The attachment bar 36 includes projecting sections 38 disposed to fit into projecting sections 40 forming part of the attachment bar 34. The attachment bars 34 and 36 provide a hinge like arrangement and both bars have openings therein to receive a pin 42 therethrough to complete the connection of one track section 14 to the next track section. The hinge pin 42 transfers track tension from section to section while allowing flexing of the attachment point as they pass around the drive sprocket and idle wheel and under the road wheels.

Referring to Figure 8, a second means for connecting the various sections is illustrated. The split cross bar arrangement includes attachment bars 44 and 46. The attachment bar 46 is designed to interlock with the attachment bar 44. A projection 48 is adapted to fit into a recess 50 in the attachment bar 44. A U-shaped connecting pin 52 is then inserted into openings 54 and 56 to securely lock the plates 44 and 46. Unlike the previous connecting arrangement, the second attachment means acts as an additional cross bar with cable flexing allowing the tread to conform to the drive sprocket, idle wheels, and road wheels.

The arrangement illustrated in Figure 8 acts as a turn-around and termination point for a continuous cable 58 looped from one end of a track section eight times to form the tension element of the tracks.

In both embodiments relating to the attachment bars, the failure of several cables due to fatigue, unusual loading, or enemy action will not incapacitate the tank. Thus, the maximum drive torque from the sprocket can be transmitted by any one of the eight cable elements in each section.

Referring to Figures 6 and 7, drive torque for moving the tank 12 is transmitted from the mechanism within the tank 10 by ten drive sprocket teeth 60.

The drive sprocket teeth engage the sections 14 of the track 12 in two rows at all times. The area around the holes in the tread is reinforced with extra urethane to reduce stresses in this area. By engaging the drive teeth directly in the compliant urethane, the drive torque is spread out over all of the engaged drive holes rather than just the one or two holes that are first to engage.

The strength of the urethane alone is sufficient to carry maximum torque drive in the embodiment illustrated, and impact loads up to the maximum track rating. However, the elastic properties of an all urethane tread is inappropriate for a track vehicle, so the steel cables embedded in the urethane carry the load and still allow excellent flexibility.

The drive sprockets 60 are attached to cylindrical elements 62 and 64. No cushions are needed since these cylindrical elements contact the urethane inner surface of the tread. Ten spherical tipped cyWin- drical drive teeth are attached to each cylindrical element. These 20 teeth engage the two holes on the track section to deliver torque and provide sprocket guidance.

The cross bars 24 in the track section 14 are not directly attached to the steel cables that pass through them, but are held in place by the molded urethane forming the track. The cross bars 24 distribute the load from the road wheels to the full width of the track when the tank is operating in soft soil, and engage ununiform rought terrain, spreading local point loads over the eight cable elements to reduce local stress concentration.

To accommodate an extra track width of two inches, for example, the arrangement illustrated in Figure 6 may be slightly modified as illustrated in Figure 7.

Referring to Figure 7, a one inch spacer 65 is added between the carrier and the final drive unit to move the tread center lines out one inch. At the road wheel and idle wheel, a two inch spacer 66 is incorporated between the two halves of the respective wheels 62 and 64 to similarly move the tread center line out one inch and also to accommodate a wider more rounded track guide.

The resulting wider stance of the road wheel provides a more suitable track interface with negotiating rough terrain, and provides better capture of the track guides as the track twists on uneven ground.

While the track embodying the present invention has been described in connection with tanks, it may be used in connection with other vehilces such as, for example, armored personnel carriers.

The invention thus provides an improved track for a light tank or personnel carrier; the track can be smoother running, less noisy and of lower weight than many previous tank tracks; it can also be more reliable and capable of higher speeds and require less maintenance. Tracks according to the invention can permit interfacing with many conventional tanks with little modification to the vehicles.

Claims (17)

1. A track section for an endless track for a vehicle, the track section comprising a plurality of cross bars transverse to the section, a plurality of cable lengths passing through said cross bars longitudinally of the section, a pair of transverse attachment bars attached to the ends of said cable lengths at the ends of the section, and a molded elastomeric material embedding the cross bars, cables and attachment bars therein to form a homogeneous track segment.

2. A track section according to Claim 1 including a plurality of sprocket openings disposed between the cross bars for receiving driving means.

3. A track section according to Claim 1 or 2 having a tread side including a plurality of traction ribs and road contact portions, and a road wheel side including a plurality of track guides.

4. A track section according to Claim 3 wherein the cross bars are embedded by the molded elastomeric material in the areas of the traction ribs.

5. A track section according to Claim 4 wherein a plurality of guides are welded to the cross bars on the road wheel side and embedded by the molded elastomeric material in the areas of the track guides.

6. A track section according to any preceding claim wherein the cable lengths pass through openings in the attachment bars and are held in place by fittings at the ends of the cables extending into the attachment bars.

7. A track section according to any of Claims 1 to 5 wherein the cable lengths are provided by a continuous cable looped through the attachment bars to form the plurality of cable lengths passing through the cross bars.

8. An endless track made up of sections according to any preceding claim joined end to end.

9. A endless track according to Claim 8 wherein the track sections are connected together by the attachment bars joined to form hinge-like arrangements.

10. An endless track according to Claim 9 wherein the hinge-like arrangements include hinge pins connecting the attachment bars to transfer track tension between the sections while allowing flexing of the attachment areas as they pass around a drive sprocket and idle wheel and under the road wheels within the vehicle.

11. An endless track according to Claim 9 wherein the hinge-like arrangements are formed by interlocking attachment bars secured by U-shaped connecting pins.

12. An endless track according to any of Claims 9 to 11 wherein road contact portions are disposed directly under the road wheel line of contact and have cross-section variations to accommodate the cross bars.

13. A track section substantially as hereinbefore described with reference to Figures 2 to 5 of the accompanying drawings.

14. A track section substantially as hereinbefore described with reference to Figure 8 of the accompanying drawings.

15. An endless vehicle track substantially as hereinbefore described with reference to Figures 2 to 5 of the accompanying drawings.

16. An endless vehicle track substantially as herein before described with reference to Figure 8 of the accompanying drawings.

17. A tracked vehicle substantially as hereinbefore described with reference to Figures 2 to 8 of the accompanying drawings.