GB720022A - Improvements in or relating to hydraulically actuated friction engaging devices - Google Patents

Abstract

720,022. Friction clutches. HOBBS TRANSMISSION, Ltd. Sept. 29, 1952 [Oct. 11, 1951]. No. 23685/51. Class 80 (2). [Also in Group XXXIV]. In a friction clutch or brake e.g. for a changespeed gear, wherein a driven disc 6 is clamped to a driving housing 10 by liquid pressure applied in a housing-space 22 to act through a rubber-like diaphragm 20, or one or more pistons, and a heat insulator-plate 19, on a presser-plate 18, and one or more (two shown) air cavities 8 in the housing 10 communicate permanently with the liquidpressure space 22 through openings 111 near the outer periphery for aircushioned clutch-engagement, as in Specification 637,269, the crosssectional area of the openings 111 is considerably less than (e.g. less than half) that of the inlet-opening which feeds pressure liquid to the space 22, whereby a reduced engaging pressure can be built up in the liquid-space 22 before that pressure is reached in the air cavities 8, resulting in reduced delay in clutch engagement. Liquid pressure reaches the space 22 from a pump 25, driven by the engine or housing 10, through a manually controlled valve 26 passages 27, 28, and an outwardly spring-pressed pressure-responsive local exhaust-valve, Fig. 2 (not shown), which, together with a centrifugal valve for automatic clutch disengagement at idle speeds, is as described in Specification 628,499. Specification 637,251 also is referred to.