608,592. Motor-vehicle driving arrangements; controlling. HARBERS, H. C. April 4, 1945, No. 8352. [Classes 79 (ii), 79 (iii), 79 (iv) and 79 (v)] A motor vehicle chassis suitable for tanks comprises a main frame supported at its forward end by a four-wheel bogie unit, steerable relative to the frame, all four wheels of the bogie being driven from two half-shafts through a differential unit having its driving shaft vertical and coaxial with the steering axis, the said shaft being drivable from an engine supported on the frame in any steering position of the bogie unit. Fig. 1 shows the main frame F of a vehicle supported at its front end by a steerable bogie T. The bogie, Figs. 2 and 3, comprises two axles 16 located by radius rods 21 or torque arms 20 on the ends of which are mounted springs S. The springs are carried by housings 19 pivotally mounted in a pair of housings 19 mounted on brackets 22 fixed to a pair of beams 23 in turn fixed to the underside of a plate 24. The latter is provided with a circular spigot 26 which is rotatable in the plate 25 which is rigidly attached to the chassis frame. The drive to the hubs is transmitted by chains 34 and sprockets 32, 33 from the half-shafts of a differential unit mounted so that its input shaft 31 projects vertically through the plates 24, 25 and is coaxial with the steering centre. Power from the motor M is transmitted to the shaft 31 through a gearbox 36, a chain and sprocket K. The rear of the chassis is supported by a similar bogie unit, the input shaft of the differential in this case being horizontal and driven from a second motor M 1 and a hydraulic coupling 59. Steering of the front bogie unit is effected by hydraulic means consisting of a piston 40 reciprocally mounted in a cylinder 39, the piston-rod 41 being connected to the bogie at 42. Fig. 6 shows the hydraulic steering layout in which a pressure pump 38 pumps oil via valves V, V 1 , V 2 , selectively to either side of the piston, or the fluid pressure may be shut off from the piston and steering effected by differential braking. The brakes are hydraulically operated by three pedals 63, 67, 67a, Fig. 5, one for the rear bogie and one for each side of the front bogie. The pedals 67, 67a have extensions 69, 69a so that they can be operated as one.