Hydraulic motor designed to run smoothly at very low rotation speeds without any need for transmission.
The term slow speed high torque motor is not strictly defined, but it is restricted to a rotation speed range not exceeding 1 to 150—250 rpm (although this does not mean that controlled "high speed motors" cannot operate in this range too).
Based on this definition, slow speed high torque motors are always piston motors (valve-controlled or multi-stroke hydrostatic motors) which deliver a torque level in keeping with the speed (up to 100,000 Nm and more).
Slow speed high torque motors, despite their relatively large size, are associated with very low inertia torque, very good starting performance and very high efficiency (Figure L 7).
Alternative: high speed motor with transmission.
Figure L 7: Efficiency of a slow speed high torque motor and a high speed motor