GB749625A - Improvements in or relating to fluid pressure operated friction clutches or brakes - Google Patents

Abstract

749,625. Friction brakes. HINDMARCH, T. July 16, 1953 [Aug. 13, 1952], No. 20372/52. Class 103 (1). [Also in Group XXIV] A friction brake or clutch, operable by the introduction of pressure fluid into a pressure cavity which forms a closed container both in the engaged or disengaged positions and which is expansible by the relative telescoping movement between members making fluid sealing engagement therebetween, is characterized in having two or more chambers or sets of chambers which are expansible under fluid pressure to engage and/or disengage the brake &c., and means to control the passage of fluid from one chamber to another chamber to control the rate of engagement &c., and/or torque carrying capacity of the brake &c. In one form, fluid under pressure is fed via a duct 9, 10, Fig. 1, into expansible chambers A, B to engage a clutch. The chambers A, B are connected by a hole 19 in a cylindrical spigot 18 which coacts with a similar spigot 17. Initial engagement of the clutch takes place due to the action of the pressure fluid in the chamber A, the hole 19 thus being opened by the axial separating movement of parts 2, 3 to allow the pressure of the fluid to build up in the chamber B to complete the engagement. Fluid under pressure is supplied through conduits 11, 12, 13 to a cavity 14 to disengage the clutch. In one modification the chambers A, B are connected by a valve V, Fig. 2, and the operating fluid can escape to the exterior of the clutch when the pressure in the duct 9, 10 falls sufficiently to allow a spring biased valve 22 to move radially inwards. Bleed holes 16 also connect the chamber B to the exterior of the clutch. The valve V can be arranged radially or axially, Figs. 4-7 (not shown), according to whether or not centrifugal force is to effect its action, and may be either of the spring biased type or may be of the type reacting only to the pressure acting upon it. Alternatively, the valve V may be of the non-return type, Fig. 8 (not shown). The restricting means between the chambers may be formed by the gaps between the spigots and more than two chambers A, B can be provided, Figs. 9, 10 (not shown). A considerable number of spigots, forming a labyrinth can be combined with a radially arranged valve, Fig. 12 (not shown). Each chamber B, &c. may contain an annular flexible piston 95, Fig. 14, tending to covre holes 98 when in the disengaged position. The clutch actuating mechanism may alternatively comprise a stepped piston 67, Fig. 17, in a corresponding cylinder 68 rotating with the clutch and to which fluid under pressure is admitted through a duct 66. The piston engages the clutch through springs 70 and levers 69. Similarly, annular stepped pistons may act upon springs to engage the clutch, Fig. 19 (not shown). Specification 622,153, [Group XXIV], is referred to.