Key element for the control of electromotors, especially for cranes and other hoisting equipment

A key element for controlling an electromotor, the key element comprising:

• a housing;
• a key switch pestle movably positioned within the housing;
• a Hall sensor positioned within the housing and connected to the electromotor for generating a control signal for controlling the electromotor;
• a permanent magnet attached to the key switch pestle and movably with the key switch pestle both towards and away from the Hall sensor, whereby, as the magnet moves towards the Hall sensor, an increased flux density is sensed by the Hall sensor thereby increasing the voltage of said control signals supplied to said electromotor;
• and
• an electric control circuit coupled between the Hall sensor and the electromotor for receiving the control signal from the Hall sensor and for providing an output voltage to the electromotor, the magnitude of the output voltage being dependent on the magnitude of the control signal, the electric circuit including a resistance decade for changing a slope of the output signal as the permanent magnet approaches the Hall sensor.