One of the major causes of forklift truck accidents is the lack of knowledge or misuse of forklift truck’s weight limit or rating capacity. Forklift trucks basically operate as a seesaw. On one end is the counterweight and on the other end is the load. The front axle is the fulcrum. The rule is that the force of the counterweight is always greater than the force of the load. This stops the forklift from tipping over.
Forklift trucks have a safe lifting capacity and height specified by the manufacturer on the rating or data plate. However, this does not mean that the forklift truck can lift any weight to the maximum height safely. The dimensions of the load, the position on the forks and the weight distribution affects the maximum load that can be lifted.
The maximum load that can be lifted is stated on the rating/data plate at a specified load centre. If load centre is not at the optimum level, the forklift cannot lift the maximum load.
Load Centre
Load centre is the balance point of a load or centre of gravity of the load, of an evenly balanced load whilst sitting on the forklift truck forks. If the load is evenly balanced on a pallet and butted up to the carriage, then the horizontal centre of gravity is half the distance from one end of the pallet. On a typical 48 inch x 48 inch (1.22m x1.22m) pallet, the horizontal centre of gravity or load point is 24 inches (0.61m).
However, how high you stack a load is also very important to achieve maximum load and height. For maximum load, the vertical centre of gravity for a balanced load should not be more than the horizontal centre of gravity, that is, for a 48 inch x 48 inch pallet, the vertical centre of gravity should not be more than 24 inches high.
In the diagram above, for maximum load capability for a balanced load, centre of gravity in the vertical direction (C) should be no greater than the horizontal centre of gravity dimension (B).
If you divert from the optimum load centre, the weight and height capability of a forklift truck reduces considerably. Often the loads are not perfectly balanced and may not be in a symmetrical shape. Therefore, the operator needs to factor in all the different parameters when lifting a load.
Rating Plate of a Forklift Truck
Forklift Truck Attachments
Sometimes forklift truck attachments such as fork extensions, booms and rotating heads are necessary to lift certain loads. However, adding attachments alters the load centre and the lifting capability of a forklift truck due to the additional weight of the attachment itself and because an attachment generally extends the truck’s load centre. It is important to seek expert advice and recalculate the loading capacity of a forklift truck after adding attachments. Fitting an attachment to a fork lift truck will reduce the truck’s rated capacity, this is known as de-rating. To indicate this reduction in capacity, a new rating plate specifically relating to the attachment for the forklift truck, must be secured to the truck before it is used with the attachment.
Forklift trucks are large heavy piece of equipment and hence paying attention to load capacity of the vehicle is important to avoid accidents, injury and damage to the goods being lifted.
Useful Links:
The Provision and Use of Work Equipment Regulations 1998 (PUWER)
Wallace School of Transport is a fully accredited RTITB company with over 50 years’ experience. You can be trained either at your own work site or at Wallace Centre in Park Royal. If you have any questions, call Wallace Forklift Training on 020 8453 3440, choose option 3 or click here to email us.