GB1103063A - Improvements in braking systems for vehicles - Google Patents

Abstract

1,103,063. Hydraulic brakes. GIRLING Ltd. 22 March, 1965 [21 March, 1964], No. 12046/64. Heading F2F. [Also in Division B7] In an hydraulic braking system for motor vehicles means responsive to movements of the steering mechanism of the vehicle is provided for cutting off the supply of fluid under pressure at a predetermined non-central position on the steering mechanism when the vehicle is travelling in a curved path. As shown in Fig. 2, the means comprises a valve assembly formed by two axially spaced pistons 26, 27 movable in response to the movement of the steering mechanism via a toothed quadrant 41, movable angularly in response to the steering movements of the vehicle, which meshes with a gear-wheel 38 and through a crank-pin 37 moves the valve assembly. The valve assembly has a central enlargement 31 which operates in a fixed sleeve 15 to control flow of fluid under pressure between a suitable source such as a master cylinder via port 11, passages 12, 13, grooves 17, 18, ports 19, 21, the bore 14, and the passages 22 and 23 to the outlets 24 and 25 so that liquid is supplied to the brakes on both front wheels of the vehicle simultaneously and at the same pressure. Small deviations of the steering mechanism will not effect the uniform application of the brakes as the axial spacing between the ports 19 and 21 is greater than the axial length of the enlargement 31. Should the brakes be applied with greater steering movement of the wheels and assuming a right-hand turn is being made the valve assembly will be moved to the right and the enlargement 31 will close the ports 21 and cut off the supply of liquid under pressure to the brake on the lefthand wheel which is the outside wheel of the vehicle. At the same time the piston 27 moves to the right and the effective volume of the part of the bore between the enlargement 31 and the piston 27 is increased so that the pressure therein is reduced and the braking effort applied to the left-hand wheel is correspondingly reduced to avoid locking or skidding of the outside wheel on the turn. As the pressure in the right-hand end of the bore 14 is reduced the inlet pressure on the left-hand end acting on the piston 26 applies to the valve member an increasing centralizing force which assists in the return of the steering mechanism to its mid-position. One-way valves 44 and 45 prevent liquid from being trapped if the brakes are released with the wheels in a turned position. In a modification (not shown) the outlets 24, 25 may be connected respectively to the brakes on both the front and rear wheels on opposite sides of the vehicle so that if the brakes are applied when the steering mechanism is operated the braking effort on both outside wheels is relieved. To meet the requirements of weight transfer when the steering mechanism is in its predetermined non-central position the brake fluid is supplied to the brake on the wheel on the inside of the curved vehicle path at a pressure less than full pressure and the supply is cut off before the full pressure is reached.