Single failure proof crane
AssigneeEderer Incorporated
InventorCharles W. Clarke
Life of this patent
Estimating the term…
Abstract
A synergistic safety system is incorporated in a crane driven by a high-speed motor which requires both an energy-absorbing torque-limiting device in the speed reduction unit and a drum emergency holding device. The energy-absorbing torque-limiting device transmits the static and dynamic torque required to rotate or hold the drum against the maximum carried load, but will slip at a pre-determined setting to absorb high-speed rotational energy of the drive train and/or torque of the drive motor in the event a two-blocking, load hang-up, overload, or engagement of the drum emergency holding device occurs. The drum emergency holding device is set automatically when the energy-absorbing torque-limiting device is actuated and/or any drive train component fails, which are detected by one or more sensing sub-systems.
Claims14
A safety system for a hoisting crane having a drum, a cable on the drum, a high-speed motor, a load drive train coupling the motor to the drum, said load drive train including a speed reduction unit, the improvement comprising:
- emergency holding means for stopping instantaneously rotation of the drum, said holding means being located outside of the load drive train so that the drum will not rotate where a failure occurs in any portion of the load drive train,
- said speed reduction unit having at least higher-speed and lower-speed reducing stages, passive energy-absorption torque-limting means located in and comprising a part of the higher-speed stage for allowing continued movement of the higher-speed stage and motor when the drum is stopped by the holding means and for dissipating the kinetic energy of the higher-speed stage and motor until the motor and higher-speed stage are brought to rest,
- means for detecting a failure of said load drive train,
- means for engaging the holding means in response to said detecting means when a failure condition is detected.
A safety system for a hoisting crane having a drum, a cable on the drum, a high-speed motor, a load drive train coupling the motor to the drum, said load drive train including a speed reduction unit, the improvement comprising:
- passive auxiliary emergency holding means for rapidly stopping rotation of the drum, said holding means being operative in an emergency hazard condition,
- said speed reduction unit having at least higher-speed and lower-speed stages,
- passive energy-absorption torque-limiting means located in and comprising a part of said higher-speed stage for uncoupling and allowing continued movement of the higher-speed stage and motor for dissipating the kinetic energy of the higher-speed stage and motor when the drum is stopped,
- means for detecting a failure of said load drive train, and
- means for engaging the holding means in response to said detecting means when an emergency condition is detected.
Dependencies are inferred from the claim text.