DIFFERENTIAL TRANSMISSION MECHANISM FOR A CONSTANT SPEED DRIVE

摘要

The differential transmission mechanism has an output differential (10). A first hydraulic displacement unit (18) having a normally fixed, approximately maximum displacement is connected to the output differential. A second hydraulic displacement unit (16) which is of variable displacement is connected to an input shaft (12). Additional components of the output differential are connected to the input shaft (12) and to an output shaft (14). An output shaft speed sensing device (32) controls the displacement of the variable displacement hydraulic displacement unit (16) to achieve a constant output speed. A sensor and control (74) responds to a reduced speed of the input shaft (12) to reduce the displacement of the fixed displacement unit (18) to effectively make the latter displacement unit a smaller, faster unit and extend the constant output speed range at the low end of the input speed range.