GB638990A - Improvements in or relating to power transmission apparatus - Google Patents

Abstract

638,990. Friction clutches ; reverse-gear ; gearcasings. HOBBS TRANSMISSION, Ltd. Jan. 20, 1948, No. 4801/47. [Class 80 (ii)] A reverse or change-speed gear includes two coaxial friction disc-clutches 6, 7 engaged, through diaphragms (or pistons) 9, 16 respectively by oil-pressure in spaces 12, 15 in a common rotary input member 1, and such engaging pressure is due to centrifugal force on the liquid, each space being connected through a constantly open exhaust-dust 32 to an outlet near the axis to obtain the maximum centrifugal pressure. An engine-driven pump 33 supplies the spaces 12, 15 through a transverse piston selector-valve 39 at a pressure which is sufficient only for filling the spaces, which are each supplied from the selectorvalve through a respective duct 26 and a pressure-responsive local exhaust-valve 23, which latter is moved radially inwards against spring- pressure by the pump-pressure so as to close off an exhaust port 30, through which the space normally drains at its outer periphery for clutch disengagement, and open the supply-duct 26 to the pressure-space for clutch-engagement. The local-exhaust valves 23 are centrifugally balanced by the liquid in their supply ducts 26. During operation oil escapes continuously at the constantly open exhaust ducts 32, and this, together with a continuous feed through a lubricating- duct 46, passes radially outwards through grooves 54 in the presser-plate 8 of the engaged clutch, thus cooling the clutch and diaphragm, and also passing over the friction surfaces of the disengaged clutch. Cooling water may also be circulated through a duct 51 in the oil-sump 71. Insulator-plates 13 are provided between the diaphragms and the spring-disengaged presser plates 8. In the reverse-gear shown the input flywheel 1 drives a parallel output shaft 5, either through the clutch 7 and a reverse-pair 61, 59, or through the clutch 6 and a forward train comprising a concentric wheel 56, meshing through a stepped idler on a countershaft (Fig. 2, not shown) with the same output-wheel 59. The clutch-supply pump 33 is on a parallel shaft driven by the engine-flywheel 1 through a gear-pair 35, which may include an idler to cater for opposite rotation of the engine, and the shaft is extended to form a power take-off 62, provided with a synchromesh clutch 64. To permit' installation on the engine with the output shaft 5 below (as shown) or at either side, each side-plate and the lower cover-plate 71 can be interchangeably mounted on the gear-casing. so that the oil-sump 71 can always be at the bottom, and the selector valve 39 can be operated from either end through one side cover-plate.