Infinitely-variable hydrostatic transmission for road vehicle has motor and pump linked by pressure regulation valve dependent on engine braking

摘要

An infinitely-variable hydrostatic transmission has a closed hydraulic circuit with a hydraulic pump (P) and a hydraulic motor (M) linked by a high pressure oil passage (53) and a low pressure oil passage (52). An oil pressure regulation valve (130) for the motor brake which releases hydraulic pressure from the low-pressure passage into the high-pressure passage if the hydraulic pressure in the low-pressure passage is less than a pre-determined value during engine braking action.