Emergency stop circuit for a direct current elevator drive

A direct current elevator drive comprising:

• a direct current motor for moving an elevator car and a counterweight in an elevator shaft and having an armature winding and a field winding;
• a braking resistance connected across said armature winding by a normally open switch contact;
• a plurality of control switches connected between said armature winding and said field winding;
• an emergency stop control connected to said control switches whereby during an emergency stop, said switch contact is closed to direct current flowing in said armature winding into said field winding to generate a torque for deceleration of an elevator car and a counterweight driven by the drive, said emergency stop control selectively varying the current flow through said field winding thereby selectively controlling the deceleration of the elevator car and the counterweight;
• and
• said emergency stop circuit including a deceleration sensor connected to said emergency stop control for sensing deceleration of the elevator car and providing a signal representing the deceleration of the elevator car and wherein said emergency stop control varies the current flowing in the field winding according to a difference between a deceleration value sensed by said deceleration sensor and a preset deceleration value.