GB753512A - Improvements in transmission systems, more particularly for vehicles - Google Patents

Abstract

753,512. Hydraulic transmission of power. EBERT, H. Oct. 16, 1953 [Oct. 18, 1952], No. 28660/53. Class 69 (2). An hydraulic transmission for vehicles comprises an hydrodynamic clutch in series with an hydrostatic infinitely variable gear. An impeller 5 of a Fottinger type clutch is integral with a driving-shaft 1, a driven member 6 being integral with a shaft 7. The shaft 7 drives a cylinder block 19 of a swash-plate type pump directly, and, through gears 20, 22, 23, 24 and a shaft 18 drives a cylinder block 29 of a second swash-plate type pump. Communication between the cylinders of the two pumps is permitted through kidney ports 35 in a control disc 34 which is fixed to a casing 51, 52 to which the output shaft 40 is secured. If the swash-plates are adjusted to give a maximum stroke to the pistons 45 of the first pump and zero stroke to the pistons 45<SP>1</SP> of the second pump, the shaft 7 is directly coupled to the output shaft 40. If the swash-plates are adjusted for maximum stroke of pistons 45<SP>1</SP> and zero stroke of pistons 45, the output shaft is coupled to shaft 18 and runs at reduced speed relative to shaft 7 due to reduction gearing 20, 22, 23, 24. The hydrostatic gearing is infinitely variable between these two limits. On starting the output shaft 40 is coupled to the shaft 7 through the reduction gearing, and just prior to that point at which a change in the reduction ratio of the hydrostatic gearing is necessary to prevent an increase in engine speed, the driving shaft 1 is clutched to shaft 7 by a disc clutch 10, 11, 12 engaged by means of a centrifugal pressure-operated control which is dependent upon the speed of the output side of the system.