GB622368A - Improvements in power transmission mechanisms - Google Patents

Abstract

622,368. Controlling change-speed gear. FORD MOTOR CO., Ltd. March 13, 1947, No. 7056. Convention date, June 26, 1946. [Class 80 (ii)] In controlling means for change speed gear comprising hydraulically operated friction band brake and friction clutch, controlled by a governor driven from the output shaft of the transmission, the clutch is engaged substantially simultaneously with the release of the brake but the latter is not released until the former has been engaged regardless of wear on the clutch friction faces., A change speed gear has brake bands A, B, C for low second and reverse epicyclic gear trains respectively, and a high speed clutch D engaged through a governor valve E and a manual selector valve 47 for the selection of low, downhill braking, forward and reverse. A pump 41 delivers fluid under pressure to the bore of the valve 47 which has radial ports 43, 44, communicable with ports 48, 49, 51 leading respectively to the engaging cylinders of the three brake. bands. A conduit 52 also passes pressure fluid from the pump through a " kick-down shift " valve 75 to a collar 68 surrounding a sleeve 63 having a pair of ports 64 and a toothed flange 61 engaged by toothed portions 59 of centrifugal weights 57 pivoted on pins 58 on a flange 56 rigid with the output shaft , 16 of the transmission. At a predetermined speed the sleeve 63 is rotated to align the ports 64 and 66 and so pass pressure fluid to the cylinder of the high speed clutch D, simultaneously the exhaust 77 is blocked by the sleeve 63 and fluid is also supplied through the conduit 39 to the cylinder 37 to disengage the brake band B by the differential pressure on the piston 36, the engaging pressure in the other end of the cylinder being provided from the pump through the manual selector valve 47 which is set for forward speed. Conversely when slowing down the sleeve 63 rotates to cut off the ports 64 and open the exhaust 77, thus dropping the pressure in the clutch cylinder and on the disengaging side of the piston 36 so that as the high-speed clutch D disengages and the brake band B engages.