GB564317A - Improvements in or relating to change speed gear mechanism, more particularly for vehicles - Google Patents

Abstract

564,317. Variable-speed gearing. BALLAMY, L. M., SHEEPSHANKS, R. H., and G.B. (NOTTINGHAM), Ltd. Feb. 18, 1943, No. 2744. [Class 80 (ii)] [Also in Group XXIX] In variable-speed gearing in which speed changes are effected by coupling gear-wheels to a driven shaft by hydraulically-actuated friction clutches, each clutch comprises a drum with an internal cylindrical surface against which an arcuate friction shoe is pressed by means of a hydraulic piston and cylinder mechanism carried by a support fixed to the shaft. As shown, a driving crank-shaft 11 has gears 45, 47, 50, meshing with gears 44, 48, 52, formed on cylindrical drums 41, 49, 53, freely mounted on a driven shaft 25. The inside of each drum co-operates with an arcuate friction shoe. As shown, for the drum 41, Fig. 2, a pair of shoes 72, 73 are pivoted at 74, 75 to a block 58 fixed to the shaft 25 and are forced outwardly to engage the clutch by levers 65, 66 connected to pistons 62 acted on by oil pressure in cylinders 60 formed in the block 58. In the case of the drums 49, 53, only a single shoe 88 is used and the piston which acts directly against an inclined surface 87, Fig. 3 (not shown), of the shoe is in the form of a ball 85. The pistons are loose fitting so that they are effective only while fluid pressure is being supplied thereto. The oil is supplied by a lubricating pump 22 via a pipe 24 and a duct 93 in the shaft 25, the distribution is controlled by an axially slidable valve 95, the interior of which is connected to the duct 93. A port 118 may register with a duct 119 to supply oil to the cylinder 120 of the clutch drum 53, and a port 115 may register with ports 83, 116, to actuate the clutch drums 41, 49. The valve 95 is adjusted axially by rack-and-pinion gearing 98, 99. When the valve 95 is in a neutral position so that the clutches are cut off from the oil supply, any oil in the clutch cylinders leaks away. A valve 123, Fig. 4, may be provided in the duct 93 to ensure that pressure fluid is supplied to the valve 95 only while one of the clutches is in operation. The valve 123 is held closed by a spring 124, and is opened by cam projections 126, 127, 128 on the valve 95 when the latter is in one of the clutch-actuating positions. In the latter positions, the valve 95 is held positioned by a spring-pressed ball 132 engaging a recess between a pair of the cam projections. Specification 562,169, [Group XXXI], is referred to in the Provisional Specification,