Forklift Load Centre
Believe it or not, you need a bigger truck to lift 1 tonne of feathers than you do to lift 1 tonne of lead. This is because of the forklifts load centre.
The load centre of any Forklift Truck represents the tipping point at the rated capacity. This is measured in how far the centre of gravity of load, along the forks a load can be carried, and to what height the load tips the vehicle over, referred to as the tipping point of a vehicle.
A simplified way to look at the load centre is to compare how far along the length the object that you are loading takes up. Most forklift trucks will be rated at having a 500mm load centre. If you were loading a block of lead weighing 1000KG, it would be around 500 x 500 x 500, and the load centre will be much smaller than the rated 500mm due to the density of lead.
However if you were to take a box of feathers, be it 2M x 2M x 2M, the load centre could be as much as 1000mm – twice the capacity of a 1 Tonne truck.
Understanding this and, many other dangers, is why forklift operators should be trained.
Most trucks will include a load centre diagram [See A] on the specification sheet with details on the trucks rated capacity, load centre and lift height from ground (unless specified otherwise on the plate). Load centre applies additionally to JIB’s, Cages and Crane attachments, of which these details will be usually stamped on a plate or on a sticker.
Reading these diagrams can take some getting used to and will differ per manufacturer on how much information is included to help the operator. Depending on where the loaded item is on the forks, this determines the load centre. If the Forklift had a set of 1 Metre forks attached, the load center would be 500mm; 600mm for 1.2 Metres; 1000mm for 2 Metres etc.
For the above specification plate, the important details are stamped as follows:
A – From ground the maximum lift height is 7450mm
B – At the maximum lift height, the rated lift capacity is 2320KG at a load centre of 500mm
B – At the maximum lift height, the rated lift capacity is 2190KG at a load centre of 600mm
B – At the maximum lift height, the rated lift capacity is 1730KG at a load centre of 1000mm
A load curve for these details would be something similar to this:
Depending on the load curve chart, some Forklift Trucks have a decreased lift height for the load carried at different heights. On the above chart the following applies:
At [A]3.3 Metres the rated capacity for a load centre of [B] 600mm is 4000KG and at [A]4.0 Meters the rated capacity for the same load centre is 3665KG.