Patent GB-541098-A (GB)
Title: Improvements in steering arrangements for motor road vehicles
IPC: B62D7/15
Filed: 1940-05-10
Abstract: 541,098. Vehicle steering-gear. TAPP, E. T. J. May 10, 1940, No. 8488. [Class 79 (v)] Relates to vehicles of the kind in which the front wheels only may be steered, the front and rear wheels may be steered in opposite directions for normal four-wheel steering, and the front and rear wheels may be steered to parallel positions for diagonal movement of the vehicle. According to the invention one pair of wheels F or one axle is provided with normal steering connections 1 .. 5 and the other axle is provided with two steering arms 19, 20 coupled respectively to independent drop arms 15, 16, means being provided whereby both said drop arms can be locked against movement so that the wheels F alone are steered, and either one of the arms 15, 16 can be coupled to the steering gear, the other being released from its lock, to impart the desired steering action to the rear wheels R when the wheels F are steered. In the construction shown the drag link 4 of the steering gear is extended rearwards by a link 10 connected to a drop arm 11 fixed on a shaft 12 passing through hollow half-shafts 13, 14 on which the arms 15, 16 respectively are fixed. Each of the shafts 13, 14 has a sliding dog-clutch member 28 or 29 splined thereon and adapted to engage either a fixed clutch member 28A, 29A in the casing 21 or a central clutch member 30 fixed on the shaft 12. The clutches 28, 29 are controlled by forks 31, 33 sliding on a fixed bar 34 and provided with rollers 39, 40 engaging cam slots in a disc 43 fixed on a shaft 44 operated by a hand lever 51. In the position shown each of the drop arms 15, 16 is locked by its clutch 28, 29 and the front wheels only are steered, the drop arm 11 oscillating idly. When the rear wheels are to be swivelled for steering oppositely to the front wheels the hand lever 51 is moved from its central notch 54 to a notch 53 and rotates the cam disc 43 to a position in which the clutch 28 is disengaged from the locking member 28A and is left in the neutral position, while the clutch 29 is disengaged from its locking member 29A and is engaged with the member 30 thereby locking the drop arm 16 to the shaft 12 and the drop arm 11 leaving the drop arm 15 free. Similarly, in order to make all the wheels turn to parallel positions, the hand lever is moved to a notch 55, the clutch 29 is released and clutch 28 is locked to the member 30, thus locking the drop arm 15 to the shaft 12 and drop arm 11 and leaving the arm 16 free. The three set positions of the cam disc 43 are determined by a spring catch (not shown) engaging any one of three notches in the disc. Instead of locking the clutch members 28, 29 to the fixed casing 21 they may be locked together. The shaft 44 may be torsionally flexible so that the hand lever 51 may be moved to change the steering conditions even when the wheels are not in the straight-ahead position, the clutch members being moved by the torsion of the shaft as soon as the wheels are in this position. When applied to a vehicle having more than four wheels the controls carried by the clutch casing 21 may be linked to more than one axle in known manner.