What are the overhead crane safeties?

An Engine Room Crane is a very important tool for the maintenance and overhaul of the marine equipment. This is because the marine equipment has weight which is too heavy and beyond the capacity of human to lift it.
The cranes come in various configuration and capacity. Generally, a E/R crane has SWL of 0.5-15 tonnes. On a medium size ship, its SWL is 5 tonnes.

Pic Courtesy: oriental precision


FIG.: Engine room crane

Safeties in engine room crane:
  1. Electromagnetic fail safe brakes

The brake pads are always in applied state and pushed by magnetic springs when not in operation or when there is a power failure.

As the crane is operated or the power is supplied, the spring gets pulled inward or compressed due to the electromagnetic effect of the current. This allows the crane to be operated normally.

As soon as power failure occurs, solenoid is demagnetized and brake is applied on the rotor. It is provided so that load do not fall in case of power failure.

  1. Limit switch on the forward, aft, port, starboard, hoisting and lowering prevents movements more than the allowed limits.
  2. Overload trip.
  3. Dead man’s handle.
  4. Emergency stop provided in remote
  5. Guards over the pulley.
  6. Locking device on the lifting hook.
  7. Mechanical locking (to avoid crane movement during heavy weather)
  8. Mechanical stoppersare provided for both directions in case the electrical distance limit trips fail.
  9. The motor is fitted with thermal protection trip. When the motor windings get overheated, trip will activate saving the winding from burning.
  10. The controls switches of the crane are push button type. While pressing only the power is supplied.

About the author

Anand Gautam

Anand Gautam is a marine engineer, Graduated from M.E.R.I. Mumbai. He likes to sail onboard ship and is one who is passionate about his job. He loves to share his knowledge, information, and ideas to everyone in a simplified way just for his satisfaction.

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