Harry Ferguson Limited

Gkn Transmissions Limited

Frederick J Walker

Anthony P Rolt

Oswald Webb

Brian Colin Pagdin

Viscous shear couplings for controlling the action of an interaxle or interwheel differential gear in a vehicle transmission are described. The couplings comprise a pack of interleaved annular plates which are free to float axially in an annular enclosure containing a viscous liquid. The enclosure incorporates a spring-loaded piston shiftable to vary the enclosure volume. The quantity of viscous liquid, in the range 85% to 100% of the minimum volume at ambient temperature, and the spring strength are chosen to give a predetermined pressure build-up within the enclosure with rise in temperature during shearing of the viscous liquid to tailor the torque-transmitting characteristics of the coupling to particular needs.

Viscous shear couplings

A vehicle anti-skid braking system is described wherein the brake-applying effort of a driver on a hydraulic master cylinder is assisted or opposed by a reversible servo-booster in accordance with the instant condition of an anti-lock sensor and an associated switch-over valve means. The booster incorporates two shiftable diaphragm actuators only one of which operates to assist braking effort, but both of which operate to oppose braking effort thereby to reduce the possibility of a driver overriding anti-skid operation during 'panic' braking. A modified system provides only a single diaphragm actuator for opposing a driver's braking effort under skid conditions.

Vehicle anti-skid braking apparatus

A control coupling in which an enclosure houses first and second sets of mutually interleaved elements in a viscous fluid. The first and second sets of elements are arranged for rotation about a common axis and for driving connection with first and second rotatable members respectively. The quantity of liquid within the enclosure and the construction of the enclosure are such that, at a predetermined working temperature of at least 100.degree. C, the pressure of the liquid in the enclosure rises substantially above ambient. At least one set of the elements is free to move in directions parallel to the common axis of rotation and at least one set of the elements is provided with facings of friction material.

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Banbury, United Kingdom

Frederick J Walker