Patent GB-847379-A (GB)
Title: Vehicle wheel anti-skid device
Inventor: BENT WILLIAM HAROLD
IPC: B60T8/74
Filed: 1956-05-09
Abstract: 847,379. Fluid-pressure brakes. DUNLOP RUBBER CO. Ltd. April 30, 1957 [May 9, 1956], No. 14337/56. Class 103 (1). In a rotary inertia device for the control of fluid pressure brakes to prevent skidding of a vehicle wheel, an annular rotatable housing encloses an annular flywheel which is rotatable relative thereto and a plurality of cam followers is associated with the housing each being spring urged into engagement with a cam surface associated with one radially extending side of the flywheel normally to maintain the flywheel and housing in a predetermined relative angular position, means being associated with the cam follower and operated by relative angular movement from the predetermined position and against the spring means to regulate the flow of pressure to the brakes. In the embodiment illustrated, an annular drum-member of rectangular crosssection, formed by two annular members 13, 14 and rotatable with wheel 3, encloses a flywheel 17 which is rotatable relative to the drummember. An annular radial ring cam 21 is located in a rectangular recess 18 in flywheel 17 to rotate therewith and is formed with four circumferentially equi-spaced depressions 22 having sloping sides 23 of equal length, and a stop 24 is provided at the outer end of each sloping side 23. A spring-urged cam-follower 25 is provided to co-operate with each of the depressions 22. Secured to one end of the non- rotatable brake housing 10 of a spot-disc brake of the kind described in Specification 688,382 is a valve mechanism 31, 33 having three conduits leading to the body; conduit 34 being connected to a source of hydraulic pressure e.g. a master cylinder, conduit 35 being adapted to be connected to a reservoir and the intermediate conduit 36 adapted to be connected to the brake operating piston and cylinder mechanism 12. A slide-valve 33 is provided with an annular groove 37 adapted to connect the inlet conduit 34 with the brake conduit 36, or the brake conduit 36 with the exhaust conduit 35. A lever 38 pivoted to the housing 10 has one end 39 in contact with the end of the slide valve 33; the other end 40 of the lever 38 abutting the rotatable annular member 30 to which the cam followers 25 are secured through a roller 41 rotatably secured to the end 40 of the lever. With normal rotation of the wheel, the flywheel 17 rotates with drum member rotating with the vehicle wheel and the cam-followers are located in the bottom of depressions 22 in annular cam 21 and the annular member 13 is in such an axial position relative to the housing 10 that the slide-valve 33, the axial movement of which is controlled by lever 38, connected to the inlet conduit 34 with the intermediate conduit 36 leading to the brakes such that hydraulic pressure may be applied to the disc brakes when master cylinder or like is actuated. Should the vehicle wheel skid, the wheel momentarily checks and the drum-member decelerates with it. The flywheel 17 overruns .the drum-member causing the cam followers 25 to move up the slopes 23 of the depressions 22 in the cam-surfaces 21 moving the annular member 30 axially outwardly against the drummember. This, acting through the lever 40 operates the slide valve 33 to connect the brakes conduit 36 to exhaust conduit 35 and thus relieves the braking pressure to allow the wheel to rotate normally once more. With the wheel rotating normally, the cam followers 25 again centralise in the depressions 22 of the cam 21 and the slide-valve 33 is moved back so that the brake can once more be applied. Specification 676,708 also is referred to.