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Hoists and Lifts

Hoists And Lifts: Every hoist or lift shall have the safe working load plainly marked on it and no load greater such load should be carried on it.

 Hoists And Lifts:

Every hoist or lift shall have the safe working load plainly marked on it and no load greater such load should be carried on it.

The cage of every hoist or lift used for carrying persons should be fitted with a gate in each side from which access is afforded to a landing and such gates should be fitted with interlocking or other efficient devices ensure that they cannot be opened except when the cage is at the land and the cage cannot be moved unless all the gates are closed.

Every hoist and lift shall be of good mechanical construction. Some material and adequate strength, properly maintained and examined by competent person at least once in every six months.

Wherever the cage is supported by rope or chain, there shall be at least two ropes or chains separately connected with the cage and balanced weight and each rope chain with its attachments should be capacities of carrying the whole weight of the cage together with the maximum load.

 Hoists And Lifts

Efficient devices should be provided and maintained capable of supporting the cage together with the maximum load in the even of breakage of the ropes, chains or attachments. There should also be an efficient automatic device to prevent the cage from over-running. Bombay Lift Act and Rules provide more details.

Lifting Machines and Types of Lifting Machines:

Overhead Travelling Cranes:

  • In the use of overhead cranes, great care should be taken for the safe and adequate means of access. It is necessary that all ladders and steps should be provided with secure hand holds and foot holds.
  • Stairways are preferable to ladders. Proper landing or stages should be provided at the point of transfer from ladder to the driver’s cabin,
  • While any person is employed or is working on or near the wheel track of a travelling crane in any place where he would be liable to be struck by the crane, effective measures shall be taken to ensure that the crane does not approach within 6,m of the place.

Jib Cranes:

  • A jib crane means a stationary or mobile crane in which suspension rope is v Supported by a projecting, horizontal or inclined member known as a jib. V It is important that capacity of the jib cranes clearly showing the maximum safe working load for the various inclination of the jibs or various positions of the trolley on a horizontal jib should be marked on the sides of the jib or on the mast or on the pillars.
  • A number of accidents have occurred due to overloading of jib cranes. It should be fitted with automatic indicators which will give efficient sound signals whenever the load being moved is in excess of the safe working load.

Bridge and Gantry Cranes:

  • These are similar to travelling cranes except that they run on rails at ground level instead of on elevated runway girders. Gantry Cranes have short spans, while bridge cranes may have spans Up to 100 m or more.
  • Bridge carries usually used for handling coal of ore. Sweep guards on nip between rail and wheels, rail clamps to prevent movement due to wind safe height of electric contact rals, operator’s cabin to be fireproof and weatherproof, 1m side clearance with the truck wheels of gantry cranes, skew switches to prevent excessive distortion of the bridge etc, are some of the safety measures.

 Hoists And Lifts

Inspection and testing of heavy duty:

  • E.O.T crane include deflection test over load test, operation test, insulation test, warning light test, earthling. And bonding check, hoist and track limit switches check, proximity warning device check, braking and locking check. Control gear check, guarding and weather protection, means of access, buffers and wire ropes of sufficient capacities.
  • All control mechanism, safety devices, leakage in air or hydraulic system, jokes and ropes, electrical apparatus, travel and steering devices should be properly checked.
  • Preventive maintenance is most desirable. Moving parts should regularly lubricated. A crane should not left unattended. Crane operators must fully trained for safe operation.

Monorails:

  • This system consists of one or more independent trolleys supported from or within and overhead truck from which hoists suspended. Monorail hoists used to raise, lower and transport materials.
  • They of three groups-hand operated, semi hand operated and fully power operated. Rail stops at the ends of monorail tracks are desirable.

Crabs and Winches:

  • These may hand operated or electrically driven Portable crabs and winches-must securely anchored against the pull of the hoisting rope or chain.
  • A dog to lock the-gears and a brake or safety lowering devices, crank-pin and gear guards are necessary.

 Hoists And Lifts

Pully-blocks or Chain Hoists:

  • These spur-geared, screw geared and differential chain hoists. They may be portable, portable but permanently hooked onto a monorail trolley. Or built into the trolley as an integral part.
  • Suitable for many operations on which a block and tackle fitted with manila rope used and stronger and more dependable than rope tackle. The ‘Spur geared type is the most efficient.
  • Screw geared and differential hoists are self-locking to automatically hold a load in position. Load carrying parts should made of steel. The load safety factor of chains should not be less than 5.

Derricks:

  • Main types are stiff-leg. A-frame, gay, ginpole and the breast derrick. With all derricks, every part should firmly anchored. Striking Lifting machines from mast, boom, still pulley block and swivel hook should be prevented.

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