Patent ID: 7353959

Claim:
A crane for lifting a load, the crane comprising: a hoisting mechanism that includes a trolley mechanism at a front of the crane with a first load sensor and a trolley mechanism at a rear of the crane with a second load sensor; an actuator subsystem including an actuator for moving at least one component of the crane; a sensor for detecting a load lifted by the hoisting mechanism, the sensor providing a load signal indicating a magnitude of the load; and a controller in communication with the actuator subsystem and the sensor, wherein the controller varies a speed of the actuator by comparing the load signals from the respective first and second sensors to a predetermined threshold, causes the actuator to operate at a high speed if both of the load signals from the respective first and second sensors are lower than the predetermined threshold, and causes the actuator to operate at a low speed if either of the load signals from the respective first and second sensors is higher than the predetermined threshold.