Patent GB-1126782-A (GB)
Title: Improvements in or relating to steering gears for tracked vehicles
IPC: B62D11/16
Filed: 1966-06-24
Abstract: 1,126,782. Differential gear. ZAHNRADFABKIK FRIEDRICHSHAFEN A.G. 24 June, 1966 [30 June, 1965], No. 28431/66. Heading F2D. [Also in Division B7] In a differential driving and steering gear for tracked vehicles wherein a travelling drive from an engine 1, via a change speed gear 2, and a steering drive from the engine 1, via a steering shaft 22 and direction reversing trains 32, 33, are connected in parallel to the track chain driving sprockets 4 via epicyclic summation gears, the steering drive is taken through a bevel wheel 19 and contra-rotating bevel wheels 20, 21 which latter are selectively connectible to the steering shaft 22 either through mirror-imaged reducing gear trains 27 surrounding the steering shaft, or, for smaller radius steering (with turning on the spot possible with suitable choice of gearing), directly. The control elements of the drives from the contra-rotating bevel wheels 20, 21 to the steering shaft 22 may include hydraulically, mechanically or electromagnetically actuated disc clutches, which, for infinitely variable steering radii, may be slipping clutches; brakes; and, to obviate changeover overlap, one-way clutches and brakes. A brake 34 acting directly on the steering shaft is provided for stabilization during straight-ahead travel. As shown, the mirror-imaged trains 27 comprise planets 30 on carriers reacting on one-way detents 31; rings 29 connected to the steering shaft 22; and suns 28 connectible to the contrarotating bevel wheels 20, 21 by clutches 24, 26. The epicyclic gears are by-passed by clutches 23, 25. In Fig. 2 (not shown), the arrangement is similar to that shown except that the clutches rendering the trains operative are disposed between the ring gears and the steering shaft. The carriers may be fixed or may react on oneway detents. In Fig. 3 (not shown), the suns and rings are respectively connected to the contrarotating bevel wheels and the steering shaft; the planet carriers are brakeable either directly or through one-way clutches; and the epicyclic trains are lockable by clutches between the carriers and the rings. In Fig. 4 (not shown), the rings are fixed; the suns are connected to (or connectible to through one-way clutches) the contra-rotating bevel wheels; the carriers are connectible to the steering shaft by clutches and one-way clutches in series (or clutches only); and the trains may be by-passed by clutches. In Fig. 5 (not shown), the suns and carriers are connected respectively to the contrarotating bevel wheels and the steering shaft; the rings are brakeable ; and the trains may be by-passed by clutches. In Fig. 6 (not shown), the rings and carriers are respectively fixed and connected to the steering shaft; the suns are connectible to the contra-rotating bevel wheels by clutches and one-way clutches in series; and the trains may be by-passed by clutches. In Fig. 7 (not shown), the suns and carriers are respectively connected to the contrarotating bevel wheels and the steering shaft; the rings are brakeable ; and the trains are lockable by clutches.