Patent classifications
B66D3/22
MULTIPLE BRAKE HOIST FOR OVERHEAD CRANE
A multiple brake hoist system includes a hoist for lifting and lowering a load and a power supply for supplying electrical power to the hoist. The power supply is configured to retain electromagnetic and capacitive energy upon deactivation. Primary and secondary brakes engage the hoist upon deactivation from the power supply. The primary and secondary brakes are connected to the power supply in a fail-safe configuration to maintain a non-engaged state on the hoist during activation of the power supply. The primary brake establishes an engaged state on the hoist upon deactivation from the power supply. The secondary brake establishes an engaged state on the hoist after a predetermined time-delay associated with consuming the predetermined amount of electromagnetic and capacitive energy of the power supply upon deactivation. In this manner, the primary and secondary brakes prevent a differential torsional stress between the mechanical components upon deactivation of the power supply.