Patent GB-588665-A (GB)
Title: Improvements in or relating to vehicle braking systems to assist steering
IPC: B60T13/36
Filed: 1944-10-19
Abstract: 588,665. Motor vehicle driving arrangements. BOLDT, W. F. Oct. 19, 1944, No. 20259. [Class 79 (ii)] [Also in Group XXIX] In a fluid pressure braking system having a driven member on each side of the vehicle and a brake actuated by a fluid motor associated with each member, a main valve is provided through which either fluid motor may be subjected to pressure or may be put at atmospheric pressure, the main valve control lever having means for locking it in either position and other means for automatically releasing it when fluid pressure is released from the operated motor. The main valve may be interconnected with the steering gear so that the resulting one-sided braking assists steering automatically, or an over-riding manual control may be used whereby one-sided braking or braking' equally on both sides may be effected, e.g., by a foot pedal. In Fig. 1 air from a compressor 1 passes to a storage tank 3, foot valve 5, to the main valve 7 and thence to either or both of conduits 8, 11 leading to power cylinders 10, 12 for actuating the brakes 9, 13 on one or both sides of the vehicle. The main valve 7 is also connected to the normal steering arm 16 by a flexible cable 33. Fig. 4 shows the main valve 7 in section and Figs. 5 and 6 are sections on lines 5-5 and 6-6 of Fig. 4. The hand lever 28 is pivotally mounted on the end of the shaft 20 which is provided with two cams 21-22 located in chambers 23, 24 separated and sealed by packing rings 25, 26, 27, the other end of the shaft 20 being resiliently connected through a coil spring 32 to the rotatable cap 30 carrying an arm 30a which is connected via the flexible cable 33 to the steering box, the arrangement being such that. the shaft 20 is rotated clockwise or anticlockwise in accordance with movements of the normal steering gear unless the shaft 20 is positively held against rotation: Chamber 23 'is in permanent communication with conduit 11 and chamber 34 with conduit 8. Each chamber has a pair of cylinders above, the diagonally opposite cylinders 36, 37 being in communication with one another and with the supply conduit 6 via passages 43, 44, the remaining two cylinders 35, 38 being open to the atmosphere via ports 45, 46. Each cylinder contains a spring-pressed valve which can be lifted off of its seat by one of the cams 21, 22. In the position shown in Fig. 4-6 with the hand lever 28 vertical, valves 51 and 55 are lifted whereby air from the supply line 6 passes to conduit 8 and 11 so that operation of the foot valve 5 causes brakes on both sides of the vehicle to be applied. Slight rotation of the shaft 20 in a clockwise direction by the hand lever 28 will close valve 51 and open valve 47 whereby pressure is released from conduit 8, the remaining two valves 55, 59 remaining as shown; thus operation of the foot valve causes brakes 13 only to be applied. Similarly, slight rotation of the shaft 20 in an anticlockwise direction will cause brakes 9 only to be applied on operation of the foot valve 5. The shaft 20 may be locked in the position shown, whereby the connection with the steering mechanism is rendered inoperative, by rocking the hand lever 28 about its pivot so that a recess 82 in its lower end engages a fixed pin (not shown). The bottom end of the hand lever 28 is formed with inclined sides so that when the shaft 20 and hand lever are being controlled by the steering mechanism the lever may ride over the fixed pin. The shaft 20 may also be automatically locked in its left hand or right hand positions by means of one of a pair of plungers 75, Fig. 4, which is ejected against the spring 77 so that its end engages the recess 82 in the lower end of the hand lever 28 when compressed air is admitted into the chamber 70. The chamber 70 is in communication with the conduit 11 and the second similar chamber is in communication with the conduit 8, so that when the hand lever 28 is moved to rotate the shaft 20 to operate the brake on one side or the other, one of the plungers 75 is ejected to lock the parts in,that position until the hand lever 28 is swung about its pivot on the end of the shaft 20 to disengage it from the pin 75 and move it to the vertical position, whereupon pressure is released and the pin 75 withdrawn by the spring 77.