12.11 SAFE USE OF MOBILE SUPPORTING STRUCTURES

When erecting mobile supporting structures, never force or hammer bolts or locking pins into place. Ensure bolt holes align; use only tools designed for this purpose and never place fingers in holes to check alignment, etc. Damaged or lost nuts, bolts, washers, etc., must only be replaced with identical items of the same size and grade. In the case of fold away and self-erecting supporting structure, do not place hands near to pivoting components which may have a scissor action. Similar attention is also necessary during dismantling operations.

Ensure the site will take the weight. The floor must be capable of sustaining the imposed point loads of the castors or jacks without movement. Where necessary, floor plates should be positioned under the mobile supporting structure to achieve these conditions. Caution must be exercised to avoid hidden dangers such as buried cables, pipes and ducts which may affect the load bearing capability of the floor on which the mobile supporting structure is to be used. In considering the point loads that will be imposed, due allowance must be made for the weight of the mobile supporting structure and its associated lifting equipment in addition to the load being lifted.

Ensure the surface is level and even. Jacks intended for the purpose may be used for minor levelling adjustments, but mobile supporting structure must not be used on slopes or inclines. Mobile supporting structures are usually fitted with light duty castors designed to sustain the load imposed by moving the mobile supporting structures only. They are unsuitable for sustaining any further load that may be imposed by the weight of the load or lifting operation. It is essential with such supporting structure that suitable jacks are used on every occasion of lift. Failure to observe these recommendations may result in the structure becoming unstable and the mobile supporting structure overturning.

Ensure the mobile supporting structure remains stable during the lifting operation. Steps must be taken to prevent inadvertent movement as this may endanger the operative or lead to the structure becoming unstable and overturning. If jacks are fitted, they should be in contact with the floor. If the wheels are fitted with brakes, these should be locked on prior to commencing the lifting operation. Similarly, rotational locks that may be fitted to castors should be in position to prevent the castor from swivelling.

The SWL of a mobile supporting structure is the maximum load for which it should be used and must not be exceeded. The weight of the lifting appliance should be allowed for in rating the mobile supporting structure. However, it should be noted that the weight of any slings and other lifting equipment form part of the load and hence may reduce the available effective lifting capacity.

Do not use the hoist hook to drag any load along the ground. Before lifting the load, ensure the lifting appliance chain or rope is vertically above the load. Failure to do this will result in the mobile mobile supporting structure moving and possibly overturning.

Never move a mobile supporting structure while lifting or suspending a load unless it is specifically designed for this purpose. They are usually designed for static use and the only permitted movement of the load is longitudinally along the runway via a suitable travelling trolley. The wheels and castors are fitted to facilitate positioning of the structure only. Attention to this point is important in operations such as loading and unloading vehicles. Unless the runway is long enough to allow unloading to the side then, after the load has been lifted clear, the vehicle should be moved to allow the load to be lowered and, if necessary, moved by another means. If further items are to be unloaded, the mobile supporting structure and vehicle should be repositioned for another lift to be made. Special mobile supporting structure can be manufactured that are suitable for movement under load, but they are comparatively uncommon. Unless the manufacturer confirms the mobile supporting structure is suitable for this purpose it should be assumed that it not. Such special mobile supporting structure are not covered by this section of the code and their use must be strictly in accordance with the manufacturer’s written instructions.

Exercise great care when handling partially suspended loads, such as when moving work pieces in and out of machine tools or removing chucks from lathes. This type of situation can lead to both swinging loads and shock loads and not only do these present a direct danger to the operative, but they can cause the mobile supporting structure to become unstable and possibly overturn.

Care must be taken when rotating loads suspended from mobile supporting structure. This should only be attempted when it can be guaranteed that the centre of gravity of the load will remain directly on the vertical centre line of the runway beam. Failure to observe this recommendation may result in load swing, shock load or the structure becoming unstable and possibly overturning.

Powered equipment may place higher dynamic loading on the structure than manual equipment, so conversion of a mobile supporting structure with hand chain hoist must take this into account. It should also be realised that the rating of the mobile supporting structure made allowance for this and for the weight of the hoist that was originally to be used on the mobile supporting structure. If a heavier hoist is fitted the mobile supporting structure may no longer be suitable for the marked SWL. If any doubt exists, consult a Competent Person.

In the case of multi-point lifting, either using two appliances on one mobile supporting structure or two separate mobile supporting structure, follow the recommendations given in section 1.9.2 Other Requirements (6 ) of this code, paying regard to the stability of the structure.

Prior to moving the mobile supporting structure, ensure any power supply systems are disconnected. The trailing ends of cables or hoses should be tied back to the structure so as not to be a hazard during the moving operation and to prevent them becoming damaged. Care must also be taken to ensure no danger arises from swinging hooks, chains or ropes.

When moving the unladen mobile supporting structure on its castors or wheels, use manual power only. Ensure the floor surface is clear of any particles or objects which may prevent the wheels from turning, e.g. stones or metal offcuts, as sudden or unexpected resistance to the movement may cause the structure to overturn. Ensure the moving operation pays due regard to any hazards and obstructions that may be present on the site, e.g. overhead cables. Ensure the structure is moved in such a way that it remains in a stable condition at all times. Jacks must be clear of the ground. Brakes or rotational locks should be released, though it is accepted that these may be used to assist with changes of direction.

Keep feet clear of wheels during the moving operation and away from jack bases when these are being lowered.

Never place ladders or climb on unrestrained mobile supporting structure as they may move and cause the ladder to topple. Great care must be taken to ensure the mobile supporting structure is not overturned during the erection or dismantling of lifting appliances, etc.