Patent GB-975527-A (GB)
Title: Improvements relating to motor vehicles
IPC: B60K17/10
Filed: 1961-11-03
Abstract: 975,527. Propelling by "stepping" action; vehicle suspension. K. SCHROTER, and F. GROSSE-SCHARMANN. Nov. 3, 1961 [Nov. 4, 1960], No. 39494/61. Headings B7D and B7H. A pair of driving wheels on a tractor is mounted so that they may be alternately reciprocatable relatively to the vehicle, the wheel which is being moved rearwardly relative to the direction of the vehicle's travel being provided with means for automatically locking it during this motion. Reference is made to four and six wheel tractors of which all the wheels are driven and are so mounted and provided, their operation being cyclic. In a tractor having two driven wheels 3, mounted for swinging about a horizontal transverse axis as shown in Fig. 1, the wheels are driven by hydraulic motors 21 and 22, Fig. 7, receiving pressure fluid from a pump 12 driven by an internal-combustion engine 10, supply and return lines 20 and 23 being provided, there being connections 24 and 25 to a pair of cylinders having pistons 15 acting upon a swashplate controller 14 of the pump 12, the pistons also being acted upon by springs 16 adjustable by screws 18 so as to give a constant output. The wheel mountings may be reciprocated by hydraulic rams 27 and 29, respectively, supplied with fluid from a pump 13 driven by the engine 10 and having its output similarly controlled through the agency of controller 14-biased off centre by a spring 19, and a pair of pistons 15 and cylinders connected by lines 31 and 32 connected to the fluid pressure lines 26 and 28 connecting the pump 13 and the rams 27 and 29. The tractor is set for forward and reverse travel according to the setting of the swashplate controller 14 of the pump 12 determined by its associated adjustment screws 18. For forward travel, fluid is supplied through the line 20 to the motors 21 and 22 and a supply of pressure fluid from the pump 13 will be provided, say in the line 26 connected to the ram 27. The rams 27 and 29 are connected on the connecting rod side by a conduit 30 and the pressure lines 26 and 28 are connected by lines 33 and 34 to opposite ends of a control valve 35 in the return line 23, whereby, when the line 26 is under pressure, so operating the ram 27 so as to propel the vehicle forwardly by moving its associated wheel mounting backwardly, relatively to the vehicle, the valve 35 is moved downwardly as shown in Fig. 7, whereby the return line from motor 21 is blocked and this motor becomes hydraulically locked, so braking the wheel. The whole output of pump 12 now passes through motor 22 so that its associated wheel moves twice as quickly and travels forwardly relatively to the vehicle, transmitting a force to the vehicle through the ram 29, the piston of which is moved forwardly in the cylinder so generating a pressure in line 28. At the end of the travel of the piston in ram 29, the pressure in line 28 becomes zero, and under the influence of the pressure in line 26, the controller 14 of motor 13 becomes reversed and a similar operation to the opposite hand now takes place. For travel in the reverse direction, the output of motor 12 is set accordingly and the connections between the pumps 12 and 13, valve 35 and rams 27 and 29 are appropriately interchanged. The rams may be single acting with no provision for reverse travel. For operating the vehicle without the stepwise action, the pump 13 is set at zero output and the valve 35 is centred under the action of springs 36 and 37, the position of the suspension units being hydraulically locked by the rams 27 and 29. In a modification, Fig. 12, the wheels are mechanically driven through a differential gear 73 and telescopic cardan shafts 72, the stepwise reciprocation being produced by rams 74 alternately supplied with pressure fluid, and, in this case, the wheel braking effect is produced by the normal wheel brakes, the wheel cylinders of which are acted upon by the difference in the pressure being supplied to and returning from the rams 74, whereby the appropriate braking effect is produced. The forward and rearward movement of the wheel suspensions produces different angles of tilt, and when not used propulsively may be utilized, under the control of a tilt valve, to correct the vehicle inclination, e.g. when travelling on a slope. The suspensions may also be moved simultaneously and locked in position to provide a vehicle of differing wheel base-lengths. The suspension device may comprise a king-pin 54 for a steerable wheel, the steering connection 51 being mounted near the rocking axis 54A so that the steering link 52 generates a conical surface in the wheel movements whereby the steering is unaffected. In an alternative wheel mounting, Fig. 11, the suspension device includes a hydraulic suspension unit 66 and a coil or air spring 67, the wheel being reciprocated by a ram 62, and the suspension and ram being mounted upon a member 63 pivotally mounted at 65 for steering. It is also stated that wheel braking effects may be provided by the provision of one-way clutches at the wheels.