Electric traction grip
Rail traction - Force-controlled grip

The operation of rail vehicles involves adjusting traction and braking forces to achieve and maintain the speeds required for line operation (equation (1) ), while limiting acceleration and deceleration, and their time derivative (jerk) for passenger comfort. Traction motor control is therefore essentially torque control.

The conversion factor between electromagnetic torque and resulting rim force can be calculated using the relationship : $F=\eta \frac{C}{\rho r}$