Patent GB-577144-A (GB)
Title: Improvements in or relating to self-propelled tracklaying vehicles
IPC: B62D49/06
Filed: 1943-12-17
Abstract: 577,144. Endless-track vehicles. ROADLESS TRACTION, Ltd., JOHNSON, P. H., and TRIPP, L. W. Dec. 17, 1943, No. 21229. [Class 79 (i)] An endless-track vehicle is provided with an endless track 3 of the "locked girder" type and a driving wheel 1, Fig. 1, which engages the front part of the track so that the groundengaging or laid part of the track is driven in compression, track-engaging means or teeth 24 on the driving wheel being kept out of engagement with the wheel-engaging means or rollers 23 on the unlaid part of the track, whereby it is ensured that under normal circumstances the wheel exerts no pull on the track, for which purpose the pitch of'the teeth 24 is made greater than the pitch of the wheel-engaging rollers 23, the effect being that the drive is practically concentrated at the point A. The whole of the load may be borne by the driving wheel 1 and idler 2, as shown in Fig. 1 ; alternatively, an intermediate load-bearing roller 33, Fig. 7, may also be provided. This roller is carried by a lever 34 pivoted at 35 to the vehicle chassis and pressed on the track by a spring 40 having a screw-and-nut adjustment 37. The upper run of the track is kept slack, and the amount of slack is adjusted by means of a screw-andnut adjustment 44 for the idler 2. In the arrangement shown in Fig. 3, a tractor 5 has road wheels 6 in front and a pair of tracks 3 at the rear. The driving sprockets 1 (not shown) are at the front of the tracks and are driven in the usual manner from the engine and gear-box through shafts in the axle casing 9. The idlers are mounted on a fixed shaft 10 secured to a tail member 11 "of the tractor. The tracks and their driving and idler wheels may be readily removed and replaced by ordinary road wheels if and when it is desired to convert the tractor into a four-wheeled vehicle, and vice versa. Endless-tracks. A suitable girder track is shown in Figs. 1, 4 and 6 and comprises alternate internal and external links 12, 13 pivoted together at 14. Each link has a ground plate 15, the internal links 12 have side plates 16 welded to their ground plate, and the external links have side plates 17 welded to their ground plates. The side plates 16 are slotted at 18 to receive abutment plates 19 welded in position, roller-path plates 20 being welded flush with the tops of the side plates 16. Hollow bosses 21 are welded to the side plates around the . hinge-pin holes 22. Rollers 23 for engaging the driving teeth 24 are mounted on the hinge pins between the bosses 21. The side plates 17 of the external links are slotted at 25 to receive abutment plates 26 welded in position, and roller-path plates 27 are welded flush with the tops of the side plates 17. The ends of the side plates 16, 17 are formed with abutment faces 28 adapted to engage the undersides of the abutment plates 19, 26 to limit the opening- out of the track. The ground plates 15 are formed with spuds 29 to engage the ground, and detachable grousers 30 may be bolted to some of these spuds. Other constructions of track may be employed, for example those described in Specifications 248,839, 306,431. [both in Class 79 (i)], 559,876 and 569,336.