GB878552A - Improvements in or relating to power transmission systems - Google Patents

Abstract

878,552. Change-speed and clutch control. ROLLS-ROYCE Ltd. Oct. 29, 1958 [Nov. 27, 1957], No. 37055/57. Class 80 (2). In a vehicle transmission of the type comprising a torque converter, a first clutch to connect the impeller and the converter input shaft, a second clutch for direct drive, and an over-running clutch between the turbine and power output shaft, control means is provided to ensure that in changing to direct drive from drive through the converter the second clutch is first engaged and the first clutch is disengaged only after the second clutch is fully disengaged. In the rail vehicle transmission shown the input shaft 10 may be coupled to the output shaft 11 through the converter 18 and a free-wheel device 15 by a clutch 13, or directly coupled thereto by a second clutch 14. The clutches are of the hydraulically operated disc type, the pressure liquid supply from inlet 30 to the clutch supply pipes 23, 25 being controlled by a piston valve 35, which may be operated manually or, as shown, by pneumatic rams 41, 42, 43 acting in series, the air supply from a cylinder 44 being controlled by solenoid shuttle valves 45, 47 operated by a hand switch 50a. In the neutral position shown a land 35c of the piston valve cuts off both pipes 23, 25 from supply inlet 30. Upon moving switch arm 50a to position O 1 valve 45 admits air through a pipe 46 to ram 41, which moves land 35c to place inlet 30 in communication with pipe 23 for engagement of converter drive clutch 13. For direct drive switch arm 50a is moved to position O 2 so that air is admitted through pipe 48 and opening 52 to ram 42, land 35c then placing inlet 30 in communication with both pipes 23, 25, so that both clutches are engaged. At the same time air from pipe 48 leaks through an orifice 57 in a vent valve 56, and passes through opening 55 to act upon the third ram 43 which, after a predetermined time interval, moves so that a second land 35b cuts off pipe 23 from inlet 30 to disengage the converter drive clutch 13. Upon moving contact 50a from position O 2 to O 1 chamber 51 is vented and air supplied through pipe 46 to ram 41; valve 56 opens to allow escape of air from chamber 54 and a spring 36 moves piston valve 35 and rams 42, 43 to the right to restore the converter drive.