Hydrodynamic-mechanical drive and brake for vehicles

Abstract

A hydrodynamic-mechanical vehicle drive wherein an engine drives the primary portion of an input clutch whose secondary portion can receive torque with varying degrees of slip and rotates the pump of a counter-rotating hydrodynamic torque converter, either directly or through the medium of a differential. The turbine of the converter is adjacent to the inlet side of the pump and drives the input shaft of a reversing gearing which utilizes a friction clutch to drive the take-off shaft forwardly and a friction brake to drive the take-off shaft in reverse. The turbine and the pump rotate in the same direction during hydrodynamic braking and the pump is then rotated at a speed which depends on the degree of slip of primary portion of the input clutch relative to the secondary portion. The clutch or the brake of the reversing gearing operates without slip during hydrodynamic braking, and the converter has a guide blade ring which is disposed between the pump and the turbine, as considered in the direction of fluid flow in the converter chamber from the pump toward the turbine. The ring changes the direction in which the fluid circulates under the action of the pump. The control system of the drive includes a control valve or an analogous component which changes over the reversing gearing in response to a braking command, and means for automatically increasing the slip of the input clutch when the control valve changes over the reversing gearing.