GB892604A - Hydro-mechanical change-speed transmission - Google Patents

Abstract

892,604. Change-speed control. BORG-WARNER CORPORATION. May 25, 1959, No. 17742/59. Class 80 (2). In a hydro-mechanical transmission for a vehicle comprising an hydraulic torque converter 22 and a double-planet epicyclic gear 21 provision is made for under-drive and overdrive to be transmitted through the converter, and for a direct drive to be established at an intermediate speed. The arrangement shown includes a converter bridging clutch 16 operated by an hydraulic piston 44; a multi-disc clutch 17 operated by an hydraulic piston 64 against a spring 66, and with an outer drum 56 engageable by a band brake 18, and an inner drum 62 integral with a sun pinion 47 meshing with planet pinions 51; a second brake 19 engageable with a drum 58 integral with the second sun pinion 48 meshing with planet pinions 50; and a third brake 20 engageable with a drum integral with the planet carrier 52. Pressure liquid for operation of the clutches and brakes is supplied by pumps 68, 69 on the driving and driven shafts 10, 11, respectively. Underdrive is effected by engaging clutch 17 and brake 18, to lock the clutch and hold the converter reactor member 26 and sun pinion 47 stationary, so that the drive is transmitted from the drive-shaft 10, through converter 22, quill shaft 12, over planet pinions 51 and annulus 49 to the output shaft 11. For overdrive brakes 18, 19 are engaged to hold sun pinion 48 stationary, the drive then being transmitted by planet pinions 50. For the intermediate direct drive, clutch 16 is engaged. For reverse drive, clutch 17 and brake 20 are engaged, to hold planet carrier 52 stationary, reactor 26 then driving in the reverse direction through a sprag clutch 29. Augmented engine braking may be obtained by simultaneously engaging clutches 16, 17 and any one of brakes 18, 19, 20, or by engaging clutch 17 and brake 20 with clutch 16 disengaged.