Mechanical Aids to Loading and Off-Loading

The time spent loading and unloading vehicles can be considerable and can therefore be costly in terms of vehicle time. Any aid to make this operation more efficient will reduce these costs and speed a vehicle’s turnaround time. Equipment that is suitable for most purposes is available, but the problem is to select the equipment most suitable for particular circumstances. To decide on the correct equipment, one must consider the following:

• Weights of materials to be handled • Quantities of materials to be handled • Nature of goods involved • Handling characteristics of the goods • Frequency of loading • Customers needs

Although in many cases vehicles are unloaded or loaded by equipment mounted on the loading bays, circumstances often require the ability of the vehicle itself to load and off-load. The following are examples of equipment used in both circumstances.

Equipment for Loading and Unloading Bays

Automatic dock levellers, or elevating platforms, are extremely helpful on loading bays because vehicle platforms vary by height. These levellers enable forklift trucks, barrows, and the like to be driven from the dock directly into the vehicle. Dock levellers may be built into the bay or be portable or power driven. Forklift trucks are widely used, and a wide range of models are available with an even wider range of fittings and adoptions (e.g., fittings for handling drums, coils, clamps for certain loads, crane hooks). Pallet loads are intended for forklift truck movement and palletisation is therefore advantageous. Cranes also have a wide range of uses in loading and unloading — particularly where large and heavy loads need to be moves — but cranes are unable to deal with large volumes. Installing cranes is costly and the amount of goods traffic unloaded must justify the high capital cost involved. Cranes do, however, have

freedom of movement within a certain area. The following are the main types of cranes available:

• Fixed jib. This crane has a single mast in a fixed position, therefore its operation area is limited. • Gantry type. This crane comprises load-bearing girders supported at each end and running on rails that gives the gantry its means of movement. On the girders is a trolley that houses the lifting mechanism that provides the traverse movement, therefore permitting traverse movement in all directions. Control is located in a suspended cabin or is maintained by a remotecontrol switch. • Wheeled type. These cranes are mounted on road wheels and are useful and mobile pieces of apparatus. Several types are available for purchase or hire. • Rail-mounted cranes. The use of these cranes is limited to areas where rails are laid. • Pully blocks and hoists. Although these are types of cranes, they are smaller than most and can usually be fixed where required for a particular job. Awkward and cumbersome loads can be unloaded with these cranes.

There are many types available, varying from traditional rape-blocks to the pul-lift types using a roller chain. • Telphers. Telphers are another type of crane that is useful for particular operations. They are cab-operated and run over a certain area on a mono, or single, overhead rail. Movement is, therefore, restricted to one direction.

When fitted with grabs, they are often used for loading loose materials such as sand, gravel, or coal.

Other loading equipment include the following:

• Pneumatic tubes are another means of handling loose materials in powder form and are often used for flour, sand, and similar materials. The tubes are laid from the loading bay to where the material is produced, and the material is sucked along the tube. • Pipelines are needed where liquids are involved. • Conveyors are also widely used in loading and off-loading materials and are particularly suited to high-volume loads, as movement is continuous and comparatively cheap. Conveyors may operate by gravity or by power. They may also be fixed or moveable. A fixed conveyor takes up considerable