GB932102A - Apparatus for augmenting hoist brake capacity - Google Patents

Abstract

932,102. Winch brakes; slewing jib-cranes. DOMINION ENGINEERING WORKS Ltd. June 24, 1960, No. 22198/60. Classes 78 (4) and 78 (5). A reversible mechanism operated by two normally alternatively-engaged clutches, e.g the slewing mechanism of a mobile crane, has provision for simultaneous engagement of both clutches for use of the mechanism as a supplementary brake on an associated hoisting drum. In a crane with two twisting drums 15, 16 (Fig. 2), on a common shaft 5 and a slewing control gear 38 driven alternatively by gears 35, 36 on a shaft 4, the two shafts 4 and 5 are coupled by gears 12, 13 and the former is driven, through transmission 3 and clutch 9, by a motor 2. Further mechanism, e.g. traversing mechanism, may also be coupled to that shown. Each drum is clutchable to its shaft 5 by a clutch 22 and each has its normal brake 18. Each gear 35, 36 also has its respective friction clutch 46, 47. The clutches and brakes are all operable in a conventional manner for normal lifting, lowering &c., but in use, if the supplementary braking, clutches 22, 46, 47 are all engaged and clutch 9 disengaged. To enable clutches 46, 47 to be engaged together the hydraulic control of Fig. 7 may be employed. In this, lever 69 of double valve 68 is operable to supply pressure fluid to one or other of clutch-operating cylinders 50, 50a. Operation of lever 91 of valve 66, however, shuts-off both cylinders from valve 68 and energizes them both simultaneously. An equivalent lever-operated mechanical linkage control system (Fig. 8, not shown), is also disclosed.