GB846354A - Epicyclic change-speed gearing for motor vehicles - Google Patents

Abstract

846,354. Change-speed epicyclic gear. SIRA SOC. INDUSTRIALE RICERCHE AUTOMOTORISTICHE. April 30, 1958 [May 4, 1957], No. 13797/58. Class 80 (2). In a motor vehicle change-speed epicyclic gear having gradual clutch engagement, as for automatic starting, plates 40, 41 of friction clutches driving suns 44, 48, respectively, are selectively clutched to an input cylinder 10, in opposition to undulating wire springs 19, by the centrifugal pressure of oil supplied constantly to chambers 13, 14 of actuating pistons 15, 16, through conduits 34, 35, 39, the chambers 13, 14 being selectively evacuated for declutching through peripheral valve ports 23, 24 opened by the attraction of spring-loaded closure-rings 25, 26 by electromagnets 30, 31 energized through slip-rings 32, 33. The strength of the springs loading the rings 25, 26 limits the centrifugal oil pressure to avoid excessive friction clutch loading at high speeds by allowing some of the oil to escape from the chambers. The diameter of the conduits 39 and the shape of the chambers are suitably chosen to avoid shocks due to excessively sharp clutching or slipping due to slow clutching. The suns 44, 48 mesh intermeshed planets carried by a freely-mounted carrier, one planet meshing a ring-gear 49 fast on a final output shaft 2. Electromagnetic brakes 53, 54 hold the carrier and sun 48 respectively. Two reduced ratios, direct drive and one reverse are as follows:-First speed, clutch 40 drives the sun 44, brake 53 holds the carrier. Second, clutch 40, and brake 54, hold the sun 48. Direct drive, clutches 40, 41. Reverse, clutch 41 driving the sun 48, and brake 53 on the carrier. In neutral, the clutch 40 remains filled. During gear-shift, gripping the shift lever energizes the clutch magnets 30, 31 to ensure the draining of both chambers and the release of both clutches, and engine speed is maintained above that required for centrifugal clutch engagement by means not described.