A torque motor is an electric motor which can continuously provide a steady torque force even while stalled. Torque motors are used where a steady feedback force is required, for operating throttles and other controls, as actuators for direct drive mechanisms, in motion control systems and many more applications.
These motors are brushless, the payload is connected directly to the rotor (there is no transmission). It is possible to describe them as rolled-up linear motors or as servo-drive motors with many magnetic poles.
High Torque at Low Speeds
Conventional motors achieve high torque only when turning at sufficient RPM. A torque motor, in order to serve its purpose, must provide adequate torque at very low RPM or even when completely and continuously stalled. It is the large number of poles and the large hollow shaft (or bore) which ensure supply of the required torque.
Direct Drive and Frameless
As described above, torque motors provide power directly and not via any type of gearbox, they are therefore classified as a special class of direct drive motors. Another feature of such motors is that they do not need a housing, bearings or any feedback providing devices. Lack of cover (housing) is a trait they share with frameless motors.
Peak Torque and Continuous Torque
Contrary to conventional motors, which are selected according to power output, torque motors are sized and selected purely based on torque. the motor selected must provide a high enough peak torque (the maximum torque that the motor can supply) and sufficient continuous torque (the amount of torque the motor can supply indefinitely even when stalled).