GB851628A - Improvements relating to change-speed gear - Google Patents

Abstract

851,628. Hydro-mechanical variable-speed gear. DAIMLER-BENZ A.G. Aug, 7, 1958 [Aug. 7, 1957], No. 25313/58. Class 80 (2). [Also in Groups XXIX and XXXIV] A change-speed gear for vehicles comprises an hydrodynamic torque converter 10 the pump 20 of which is driven by a planet carrier 39 of an epicyclic gear 11 having a ring gear 16 fast with an input shaft 14; the ring gear and sun gear 22 being fast with the pump 17 and turbine 24 respectively of a turbo coupling which is filled to drive the ring and sun gears at the same speed to lock the epicyclic gear so that the pump 20 of the converter is driven at the speed of the input shaft, and is emptied to give reduced ratio drive of the pump 20, the ring gear being held stationary by a free-wheel 26. The converter turbine 29 is fast with a driven shaft 30 which can be clutched to an output shaft 34 by a clutch 32 for direct drive, and which drives the output shaft 34 in reverse on disengaging clutch 32 and engaging a clutch 62 to lock the planet carrier of an epicyclic gear 12 having a sun 31 fast with the driven shaft 30 and a ring gear fast with the output shaft 34. In order to provide hydrodynamic as well as engine braking, the ring gear 22 and turbine 24 are held stationary by engaging a clutch 25. The engine and pump 17 are driven by way of epicyclic gear 11 from the torque converter with a stepped-up speed of rotation. The hydrodynamic braking can be adjusted by regulating the filling of the turbo coupling, this is effected by controlling the rate of supply of liquid; the pressure in the coupling opens a throttle valve (not shown) so that a constant flow is provided through the coupling for cooling purposes. The coupling is supplied with liquid through a duct 58, the pressure in the duct moving a piston valve 57 inwardly to close an exhaust port 60. If the pressure in the duct is removed, e.g. by kick down, piston 57 flies outwards under spring and centrifugal action, so that port 60 is opened to rapidly empty the coupling. The coupling pump 17 is secured to the torque converter housing 15, which is fast with the input shaft, by means of a sleeve 36 having a flange 37 secured to the housing 15 by bolts 38 which also secure the ring gear 16, the flange 37 is of sufficient diameter to allow the epicyclic gear 11, and other parts subject to wear, to be removed from the housing.