Stall torque is the

torque In physics and mechanics, torque is the rotational analogue of linear force. It is also referred to as the moment of force (also abbreviated to moment). The symbol for torque is typically \boldsymbol\tau, the lowercase Greek letter ''tau''. Wh ...

produced by a mechanical device whose output rotational speed is zero. It may also mean the torque load that causes the output rotational speed of a device to become zero, i.e., to cause stalling. Electric motors, steam engines and hydrodynamic transmissions are all capable of developing torque when stalled. Stall torque is often expressed in units of kg·cm.

Electric motors

Electric motor An electric motor is a machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a electromagnetic coil, wire winding to gene ...

s continue to provide torque when stalled. However, electric motors left in a stalled condition are prone to overheating and possible damage since the current flowing is maximum under these conditions. The maximum torque an electric motor can produce in the long term when stalled without causing damage is called the ''maximum continuous stall torque''.

Hydrodynamic transmissions

A hydrodynamic torque multiplier (torque converter) produces stall torque when the load prevents the turbine (output stage) from rotating while the pump (input stage) is being driven. In most cases, damage due to overheating occurs if the stall condition persists for any significant length of time.

Combustion engines

In the case of a petrol (gasoline) or

Diesel engine The diesel engine, named after the German engineer Rudolf Diesel, is an internal combustion engine in which Combustion, ignition of diesel fuel is caused by the elevated temperature of the air in the cylinder due to Mechanics, mechanical Compr ...

, the stall torque may refer to the torque load that causes the engine to stall. The actual amount of torque is dependent on engine

RPM Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or r⋅min−1) is a unit of rotational speed (or rotational frequency) for rotating machines. One revolution per minute is equivalent to hertz. Standards ISO 80000-3:2019 def ...

and throttle opening.

References

{{Reflist Mechanics Machines