| 摘要 |
1,268,932. Anti-skid braking systems. SIMMS GROUP RESEARCH & DEVELOPMENT Ltd. 2 March, 1970 [6 March, 1969], No. 11902/69. Heading F2F. In a braking system for a vehicle wheel including brake operating means, a pump 15 having a liquid output adapted to increase with wheel rotational speed is arranged to withdraw liquid from a reservoir 13 and return the liquid thereto after circulation through a conduit having a connection to the brake operating means, and brake applying means located downstream of the connection is operable to add a restriction into the conduit and arranged so that liquid pressure in the connection is increased. A leakage path by-passes the brake applying means and incorporates a variable restriction providing a resistance to liquid flow which decreases automatically with increased wheel rotational speed, and a fixed restriction in series with the variable restriction. As shown, depression of a brake pedal 1 results in fluid pressure from master cylinder 3 being applied via conduit 6 and annulus 7 in valve 5, conduits 10 and 11 to the brake applying means of the wheel 12, fluid fed by the pump 15 to a conduit 16, via conduits 29, 33 and conduit 28, to reservoir 13 and not being obstructed by tapered portion 8 of the valve 5. Further depression of the pedal 1, causes the portion 8 of the valves to obstruct the connection between conduits 33, 28 and fluid pressure generated by the pump is applied to the plug 31 in cylinder 30 comprising the brake operating means to apply the brakes; this generated pressure can leak back via conduit 28 via the leak off path provided through conduit 19. In the leak-off path is a spring- loaded shuttle 22 having tapered flats 23 which create with an annulus 25 a variable restriction in series with a main restriction 27. With high rotational wheel speeds a relatively high differential pressure is generated across a sensing restriction 17 to force the shuttle to the left as seen in the Figure to render the main restriction 27 unaffected with low rotational wheel speeds, the shuttle is urged by spring 24 towards the right when the restriction 17 controls the leakoff path. The restriction 17 may be incorporated in the housing of the shuttle 22. The system may be applied to each wheel of a vehicle, there being a pedal 1 and master cylinder 3 common to all systems, or applied to pairs of wheels and the pump may be driven directly by a wheel or some other part of the vehicle transmission.
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