METHOD AND APPARATUS FOR AN EMERGENCY LOWERING KIT

摘要

A method and apparatus are disclosed for lowering a load on a direct current hoist motor during an electrical power interruption, the method including but not limited to determining in a crane processor that the electrical power interruption has occurred; and providing a brake assist current to shunt field on the direct current hoist motor to produce a counter torque in the hoist motor.

主权项

1. A system for lowering a load on a direct current hoist motor during an electrical power interruption to the direct current hoist motor, the system comprising:
a crane processor in data communication with a non-transitory computer readable medium; a first computer program component that determines in the crane processor that an electrical power interruption to the direct current hoist motor has occurred; and providing a brake assist current to a shunt field on the direct current hoist motor to produce a counter torque in the direct current hoist motor; a second computer program component that electrically connects a variable resistance brake assist resistor in series with a dc power supply and the shunt field wherein a brake assist resistance value for the variable resistance brake assist resistor is controlled by the crane processor; and a third computer program component that varies the brake assist resistance value proportionately to a measured hoist hook speed to proportionately increase the brake assist value to proportionately provide counter torque with an increase in hoist hook speed.