IE54201B1 - Track sets for vehicles - Google Patents

Abstract

A track set for connection to an axle assembly (12) of the traction wheels of a vehicle or a trailer consists of a track set frame (6), a drive wheel (4), two track wheels (8,19), a track mat (3) and a track mat tensioning mechanism (9). The track wheels (8,19) are located at the forward and rearward ends of the track set respectively. The drive wheel (4) is adapted to be connected to the traction axle (12) and is located between and above the track wheels (8,19). The tensioning mechanism (9) comprises two rollers (5,20), one located forward of and the other to the rear of the drive wheel (4). The rollers (5,20) are spring-loaded to urge the track mat (3) mainly downwards so that the contact angle between the track mat (3) and the drive wheel (4) is maximised. The interval between the teeth of the drive wheel (4) is substantially larger than the meshing element of the track mat (3) entering this interval, and the pitch of the track mat (3) is larger than the pitch of the drive wheel (4). The track set enables various kinds of standard type land vehicles, such as agricultural, forest and bog tractors and their trailers to be converted into track- borne vehicles, and operates reliably even in difficult conditions.

Description

This Invention relates to a track set for a vehicle, consisting of a track set frame, at least two track wheels, a track mat and a track tensioning mechanism and attachable to the axle assembly of the traction wheel of a vehicle and/or trailer.

When aiming to Increase the transporting capacity of 5 transport equipment travelling over soft ground areas, such as woodland or bogs, one is compelled to replace conventional designs based on the use of wheels with track sets. In the track set designs of track-borne vehicles known In the art, the traction or drive wheel 1s usually placed at one end or -the other of the track assembly. However, providing for mechanical power transmission 1n this design calls for an expensive and complicated chassis construction of the vehicle.

Another track set design known in the art Is that 1n which the drive wheel has been disposed centrally 1n the track assembly. It 1s then easier to provide for proper power transmission, but the length of the track assembly 1s limited.

This Is because a large enough contact angle 1s required between the drive wheel and the track mat.

When a track set Is desired which enables various kinds of standard type land vehicles such as agricultural, forest and bog tractors and their trailers to be converted Into track-borne vehicles the track set must be directly connectable to the axle assembly of the traction wheel of the -25 4 2 0 1 vehicle or trailer. This precludes the disposing of the drive wheel to be located at either end of the track set.

An efficient enough track set cannot be achieved by those drive wheel designs either 1n which the drive wheel 1s placed In the central region of the track set, to serve this purpose, because a centrally placed drive wheel can only be used In the case of short track sets.

The present invention alms to eliminate the abovementioned drawbacks and to provide a track set which 1s substantially superior in efficiency to any design of the prior art, and which 1s connectable to the axle assembly of the traction wheel of a vehicle or trailer.

According to the tnventlon there is provided a track set for a vehicle, consisting of a track set frame, a drive wheel, at least two track wheels, a track mat and a track mat tensioning mechanism, said track set being connectable to the axle assembly of the traction wheels of a vehicle and/or trailer and two track wheels of the track wheels of said track set being located In the lower part of the track set, one track wheel being located at the forward end of the track set and the other track wheel being located at the rear end of the track set, wherein the drive wheel Is adapted to be connected to the traction axle of the vehicle and 1s located asubstantlally in the central part of the transverse width of the track mat of the track set between and above the track wheels located at the ends of the track set, wherein the tensioning mechanism comprises -3two rollers, one being located forward of the drive wheel and the other rearward of the drive wheel, and wherein the rollers of the tensioning mechanism are spring-loaded to urge the track mat mainly downwards so that the contact angle between the track mat and the drive wheel 1s maximised.

Preferably, the rollers of the track mat tensioning mechanism are disposed on the ends of levers rotatably carried on the axle assembly of the drive wheel. According to a preferred embodiment, the levers of the tensioning mechanism are loaded with at least one spring to be tumable with respect to each other, the rollers being disposed to urge the track mat against the drive wheel so that the contact angle between the track mat and the drive wheel Is maximised.

The tensioning mechanism 1s preferably tumably carried on the axle assembly of the drive wheel in such a manner that 1t is freely tumable with varying tension of the track mat on different sides of the drive wheel depending on the direction of rotation of the drive wheel and on the operating conditions.

The material of the track mat desirably consists of fabric-reinforced rubber belt and the material of the drive wheel and/or the track wheels Is desirably polyamide. The track set may further comprise, 1n addition to the track wheels, one or more carrying wheels located between the track wheels. The or each carring wheel is preferably made of polyamide. -454201 The invention will now be further described, by way of example, with reference to the drawings, 1n which : F1g. 1 is a side elevation of a tractor and trailer on which have been mounted track sets according to one embodiment of the Invention; Fig. 2 1s a side elevation of a second embodiment of a full track set according to the invention for mounting on a tractor.

Fig. 3 1s a part-sectioned plan view of the track set shown In Fig 2; and HO Fig 4 shows a detail of a track set according to the invention with the drive wheel and the track mat tensioning mechanism schematically indicated.

Referring now to F1g. 1, In the agricultural tractor 1 therein depicted, track sets according to the Invention have been mounted to replace Its rear wheels, and on the axle of the trailer 2. It is seen in Fig. 1 that 1n order to maintain the track mat 3 1n engagement with the drive wheel 4, tensioning wheels 5 and 20 have to be used, In this embodiment, the track set is symmetrical with reference to the vertical plane passing through the axle.

In Figs. 2 and 3 1s depicted a track set according to the Invention Intended to constitute the full track set of an agricultural tractor. In this embodiment, the track set has greater length forward of the drive axle 12, extending up to the front axle, 14, to which it has also been connected by a suspension. ;5 In other respects the construction is equivalent to that shown in F1g. 1. The track set consists of a frame 6, the drive wheel 4, track wheels 8 and 19, carrying wheels 7, »5= 4 2 0 1 the track mat 3 and a track mat tensioning mechanism 9. The tensioning mechanism 9 comprises levers 21 and 26 loaded by springs 17 and 23, the tensioning rollers 5 and 20 being mounted on the ends of these levers. The frame 6 of the track set 1s connected to the rear axle 12 of the tractor by means of a pivot element 10 and to the front axle 14 by means of a linkage rod 11. The carrying wheels 7 are mounted on arm members 27, pivotally carried on the frame 6 of the track set by means of respective pivots 15. The drive wheel 4 is' affixed by a drive wheel fixing element 13 which replaces the tractor's rear wheel. The tensioning mechanism 9 1s rotatably carried in the drive wheel fixing element 13.

The track mat 3 consists of a track belt 18 and of meshing elements 16. Parts 3a and 3b of the track mat are connected to each other by track pieces 3c and, as shown in Fig. 3, the central part of the transverse width of the track mat 1s maintained in engagement with the drive wheel 4 by means of the tensioning rollers 5 and 20 of the tensioning mechanism 9. The tensioning force 1s adjustable by means of the springs 17 and 23. It 1s advantageous to set the rigidity of the springs such that the mechanism allows the track mat on the traction side to straighten and to yield in resPonse to roughness of the ground, to stones, stumps or the like, and at the same time prevents oscillation of the track mat due to sudden Impact loads. The Interrupted lines 1n Fig. 2 Indicate the movements of the track mat 3 and of the tensioning mechanism 1n different loading cases. ^g· 4 Illustrates the co-operation between the track set -654201 drive wheel 4 and track mat 3 of the track set according fo the invention. With a view to obtaining play-free operation, the dimensioning of the track mat 3 and of the drive wheel 4 has to be adjusted so that the pitch of the track mat 3 § when the track mat is on the drive wheel 4 is wider by a suitable amount than the tooth pitch PVpj of the drive wheel. Hhen this condition is met, sliding will occur between the tooth 24 of the drive wheel 4 and the meshing element, or track pad 16 of the track mat 3 which 1s 1n engagement, for which reason the bottom of HO the tooth interval 25 will·be scraped clean. By proper selection of the dimensioning of the drive wheel 4 and track mat 3, a desired magnitude of the contact angle β between them Is obtained for accomplishing play-free operation e.g. 1n connection with reversal of direction and of unexpected loads. It is seen In F1g. 4 that as a drive wheel 4 rotates through the contact angleB the track pad 16 of the track mat 3 slides 1n the tooth Interval 25 of the drive wheel 4 so that the track pad 16 moves from one boundary to the other of the tooth Interval 25.

It will be evident to a person skilled 1n the art that different embodiments of the Invention may vary within the scope of the following claims.

Claims (10)

1. A track mat set for a vehicle, consisting of a track set frame, a drive wheel, at least two track wheels, a track mat and a track mat tensioning mechanism, said track set being connectable 5 to the axle assembly of the traction wheels of a vehicle and/or trailer and two track wheels of the track wheels of said track set being located in the lower part of the track set, one track wheel being located at the forward end of the track set and the other track wheel being located at the rear end of the track set, wherein the drive wheel is adapted to 10 be connected to the traction axle of the vehicle and is located substantially in the central part of the transverse width of the track mat of the track set between and above the track wheels located at the ends of the track set, wherein the tensioning mechanism comprises two rollers, one being located forward of the drive wheel and the other rearward of the drive 15 wheel, and wherein the rollers of the tensioning mechanism are springloaded to urge the track mat mainly downwards so that the contact angle between the track mat and the drive wheel is maximised.

2. A track set according to claim 1, wherein the rollers of the track mat tensioning mechanism are disposed on the ends of levers 20 rotatably carried on the axle assembly of the drive wheel.

3. A track set according to claim 2, wherein the levers of the tensioning mechanism are loaded with at least one spring to be turnable with respect to each other, the rollers being disposed to urge the track mat against the drive wheel so that the contact angle between the track 25 mat and the drive wheel is maximised. -854201

4. A track set according to any one of claims 1 to 3 wherein the tensioning mechanism is tumably carried on the axle assembly of the drive wheel in such a manner that 1t is freely turnable with varying tension of the track mat on different sides of the drive wheel depending on the direction of rotation of the drive wheel and on the operating conditions.

5. A track set according to any one of claims 1 to 4, wherein the material of the track set consists of fabric-reinforced rubber be!to

6. A track set according to any one of claims 1 to 5, wherein the material of the drive wheel 1s polyamide.

7. A track set according to any one of claims 1 to 6, wherein the material of the track wheels is polyamide.

8. A track set according to any one of claims 1 to 7, wherein the track set comprises, In addition to the track wheels, one or more carrying wheels located between the track wheels.

9. A track set according to claim 8, wherein the or each carrying wheel is made of polyamide.

10. A track set for a vehicle substantially as described herein with reference to the drawings.