A ship is a huge floating structure which is propelled with the help of a main engine, along with several other machinery and systems inside the engine room which require proper operation and continuous maintenance. Maintenance and repair of engine room machinery requires moving of heavy parts from one place to another. As individual parts of main engine and machinery of ship weighs in tonnes, engine room crane operation and safety plays a major contribution for the continuous operation of the ship. In this article we will learn about one such equipment which helps immensely in this process – the engine room crane.
General Description of Engine Room Cranes
The merchant vessels are fitted with engine room cranes mainly as per the main engine specification. This is done so that the crane can lift all the individual parts of the engine during routine maintenance. Normally, the capacity range for these cranes is from o.5 to 15 tonnes.
Sometimes two cranes are fitted in an engine room, where in space and reach is a problem, to simplify the lifting operation. One crane with two hoists is also commonly fitted onboard.
The engine room crane consists of a motor coupled with wire drum so that the motor can lift or lower the crane hoist by winding or unwinding the wire over the drum. The whole system is then fitted in a trolley.
Two pathways are built with a rack and pinion arrangement, both in transverse and longitudinal direction of the engine room and over the main engine, where the trolley is placed so that the whole unit can move fore-aft and port starboard.
A remote is provided so that the crane can be operated from any position, thus allowing the user to keep a safe distance from the lifted load. It is the duty of the responsible engineer onboard to operate the crane and to have regular checks on the safety and working of the crane. Second engineer is responsible for operation, maintenance and safety checks of the engine room crane.
Safety Features of Engine Room Crane:
1) The most important safety feature of the crane is the electromagnetic fail safe brakes which do not allow the crane to fall with the load even when there is failure of power. For this:
- Normally centrifugal brakes are used which are fitted inside the rotating drum.
- 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.
2) Emergency stop is provided in the remote so that the operator can stop the crane at any time.
3) The motor is fitted with distance limit switch in both transverse and longitudinal direction so that the travel of the trolley and hence crane should not overshoot the rack’s end.
4) Mechanical stoppers are provided for both directions in case the electrical distance limit trips fail.
5) The up and down travel of the hook is also attaches with automatic stopper to avoid overloading of the motor.
6) The motor is fitted with thermal protection trip. When the motor windings get overheated, trip will activate saving the motor winding from burning.
7) Load limit switch is also fitted which will trip the motor if the load to be lifted is above the crane capacity.
8) It’s the responsibility of senior officers to operate the crane and to make sure all the personnel involve in any lifting operation are at a safe distance during operation of the crane.
9) Additional tools like i-bolts, shackle, wire sling, belts etc. used for lifting must be checked before use.
10) It should be noted that no one walks or stand below the crane when it is in the loaded condition.