12.1 FOREWORD

Mobile supporting structures are widely used in industry in conjunction with hand or power operated lifting appliances where a temporary runway structure is required to perform both lifting and linear moving operations. They represent a cost effective method of providing a lifting structure where the purchase of a permanent installation cannot be justified or where the load cannot be positioned under a fixed structure. Their portability allows convenient use in multiple locations, but also imposes certain restrictions on use. They are usually available up to 5 tonne capacity, although higher capacities can be manufactured and the code is not restrictive in this respect.

Mobile supporting structures are not intended for movement under load. They are mobile supporting structures which may be moved from one place to another to enable the runway to be positioned over the point of lift. The only intended movement of the raised load is along the runway.

It should be noted that special mobile supporting structures can be manufactured which are suitable for movement under load, but are uncommon due to their high cost compared to other methods of handling and moving loads. Caution must be exercised as such designs are often visually indistinguishable from standard mobile supporting structures designs. Unless explicitly confirmed by the manufacturer, assume the mobile supporting structure is of standard design. Such special mobile supporting structures are not covered by this section of the code and their use must be strictly in accordance with the manufacturer’s written instructions.

Typical examples of the use of mobile supporting structures are loading and unloading in yards and open areas, the installation/removal of plant and equipment and periodic maintenance purposes; in fact any application where a lifting point, runway or crane cannot conveniently or economically be permanently installed. There are currently only a small number of standards that cover mobile supporting structures, but those that do generally classify them as manually operated light cranes. As a mobile supporting structure is essentially a movable runway structure, it should be designed, manufactured and tested in accordance with those standards relevant to runways and manual light cranes as applicable.

It must be realised that a mobile supporting structure cannot on its own be used for lifting operations, or classed as a light crane, and only becomes an effective lifting structure when fitted with a hoist, hoist and trolley or similar lifting appliance.