6.10.3 Maintenance
A routine preventive maintenance programme should be drawn up which can be combined with the maintenance programme that will be necessary for the associated power supply system and control equipment. This should meet the requirements set out in the manufacturer’s installation and maintenance instructions in addition to any requirements of the particular site due to the conditions of service. In any event attention should be given to the following points:
Load chains should fit snugly into the pockets of the load wheel and as the load wheel turns the chain should enter and leave the pockets freely. This action is assisted by a chain guide and stripper which should be checked for correct fitting and operation. The chain should be lubricated in accordance with the manufacturer’s instructions. Recommended further guidance on the maintenance of load chains may be found in ISO 7592. (Some examples of chain hoists using roller chain may still exist. These have the limitation that the chain will only articulate in one direction and different maintenance procedures will apply. Such hoists are not covered by this section of the code and the advice of a Competent Person should be sought.)
Wire rope should coil correctly onto the drum. It must move freely on and off the drum in a single layer with no crossing of the strands. The correct number of full turns of rope must remain on the drum when the bottom hook is in its lowest position and the limit has operated. This will vary between 2 and 3 full turns dependent on the hoist design and the manufacturer’s instructions must be followed. If any doubt exists ensure 3 full turns remain. Commonly, a rope guide and band is used to assist the rope to coil correctly these should be checked for correct fitting and operation. The wire rope should be lubricated in accordance with the manufacturer’s instructions.
The recommended grade of acid free chain or wire rope lubricant should always be used. Care should be taken to ensure it penetrates between the wires of wire rope or the bearing surfaces of the chain. Under certain conditions of use, such as where there is a risk of contaminating other goods or products or in dusty atmospheres where dirt is liable to mix with the lubricant and adhere to the chain or wire rope, a suitable dry lubricant may be used. Details are available from the hoist supplier.
In all but the most special of cases, the bottom terminal fitting will be a swivel hook. They must swivel freely, bearings and swivels should be lubricated in accordance with the manufacturer’s instructions. In the case of multi-fall hoists, the pulley sheave or loadwheel must be checked for free movement and the axle pin and bearings should be lubricated in accordance with the manufacturer’s instructions. Safety latches should be in good working order and the spring should cause the latch to close completely.
The suspension fitting will vary with the design of the hoist. Hooks, eyes and similar suspension fittings may be fitted with swivels or be arranged to rock in one plane only. They must articulate freely and swivels or rocker pins must be lubricated in accordance with the manufacturer’s instructions.
Trolley wheels must movefreely, wheel bearings, axle pinsand drivegears should be lubricated in accordance with the manufacturer’s instructions. Anti-tilt devices must be correctly set to the underside of the beam and should be reset if necessary. Further guidance in respect of trolleys is given in x-svn:///svn/leea/dita/xml/topics/TOP_00000000/TOP_00000323.html of the code.
The pendant cable control should be suspended on a wire, chain or cord internal or external to the cable, which ensures that no load is imposed on the cable, cable glands or terminals. This should be inspected on a regular basis. The cable should be visually checked and if necessary tested to ensure that there has been no deterioration of insulation or breakdown of the cable particularly at gland entries. The control unit should also be checked for its general condition, legibility of legends and correct operation.
Hoisting and travel limits should be checked to ensure that they are correctly set and that the limit mechanism and switches operate freely and correctly. Ensure any necessary lubrication of shafts and linkage points is undertaken.
In the case of any hoist arrangement which incorporates contactors, whether internal to the hoist or as part of the control gear, they should be checked for wear and signs of arcing. They should be cleaned, maintained or replaced in accordance with the manufacturer’s instructions.
The slipping clutch, where fitted, is a safety device so its correct operation is essential. It should be checked and if necessary reset in accordance with the manufacturer’s instructions.
Various types of gearboxes are used in the construction of electric power operated hoists. Some are filled with oil, which may require regular ‘topping up’ and occasional draining and replacement. Others are packed with grease and may be sealed for life or require periodic repacking. It is therefore of the utmost importance that lubrication of the gearbox is undertaken strictly in accordance with the manufacturer’s instructions. Similarly, various types of bearing may be used. These should be checked for freedom of movement and if necessary lubricated in accordance with the manufacturer’s instructions.
Dependent on the application and type of brake fitted, the wear rate will vary. As this item is most critical to the safe operation of the hoist, regular inspection and adjustment in accordance with the manufacturer’s instructions are essential. They should be subjected to regular functional checks and any undue noise investigated.
The general condition of the hoist should be maintained in good order. It should be cleaned of any dirt which may have accumulated, paying particular attention to load wheels, pulleys, etc. where such accumulations may impede the correct operation of the hoist. Only cleaning agents recommended by the hoist manufacturer should be used, taking care to follow his instructions.