Behaviour of a hydraulic motor on transition from standstill to motion. Due to its design and the related friction and leakage losses, during starting a motor outputs a significantly lower useful torque (starting torque) at the shaft than the theoretical torque.
The starting quality of a hydraulic motor is characterised by its starting torque, the pressure required on stating without load as well as the magnitude of the starting jerk (= speed jump) and the lowest rotation speed (slow running behaviour).
Along with the installation-related causes of friction (hydromechanical efficiency) these parameters depend on the kinematic relative delivery fluctuation of the motor and the speed-dependent leakage oil flow.
The starting behaviour of slow speed high torque motors is generally superior to that of high speed motors.