The load carrying capacity of a forklift is indicated on the capacity data plate or name plate and should be found affixed to the forklift in a prominent location in view of the operator. This data plate will indicate the maximum lifting capacity of the machine to the full extension height of the mast and a specified load center for a given configuration. If the forklift configuration or the load characteristics have changed since the data plate was issued, if the data plate is unreadable, or if there are special new load handling conditions, a capacity plate should be changed or added to reflect the relevant forklift, attachment and load conditions. This is extremely important because a warehouse manager and a trained forklift operator will first look to this data plate and rely on this information for the maximum load that can be safely handled with the machine.
There are a multitude of factors that affect the lifting capacity of a forklift and these parameters, which are indicated on the capacity data plate, include:
- Make or Manufacturer
- Power Source
- Battery Weight (for electrics)
- Tire Type
- Tire Size
- Mast Lift Height
- Mast Carriage Type
- Attachment(s) Type
- Attachment(s) model
- Load Center of Gravity (CG or LC)
If any of these parameters are changed, particularly the attachments on the forklift carriage or the load center, the capacity plate should be checked for accuracy to ensure safe load handling.
Forklift Attachments Change the Capacity of the Lift Truck
A forklift attachment includes anything that is attached to the front carriage of a forklift or is attached to an attachment on the forklift. A typical forklift attachment configuration might include a hang-on side shifter and two forks. In this case, if the forks are removed and longer forks are added, the capacity of the machine could be drastically reduced. Or if the forklift is used to pick up a fork mounted attachment, such as a drum handler or fork extensions, then a capacity data plate must be changed or added to reflect the new configuration. OSHA safety regulations state that a forklift must have a legible capacity plate to reflect any attachment used on the lift.
Capacity Decreases the Higher the Forklift Lifts
Lift height or maximum fork height (MFH) has a significant effect on a forklift’s load carrying capacity, and forklifts with high masts will have a greater carrying capacity at lower lift heights than at the maximum lift height. For this reason forklifts with very high masts may have a dual capacity rating on the data plate; a maximum capacity up to a mid level lift height, and a lower capacity rating at the maximum lift height. This allows the forklift operator to work with heavier loads at low heights, i.e. loading and unloading trucks, cross-docking, etc., while using the same forklift to put away lighter loads to high storage locations.
If the Length of the Load is Longer, Lifting Capacity is Reduced
Because a forklift is using leverage to lift a load, any condition that adds weight to the front of the forklift and causes the load center (LC or CG) of the load to be moved further away from the forklift will contribute to a reduction in the residual carrying capacity of the machine. Attachments can cause these reductions, as well as the dimensions of the load and the load handling conditions. Load center typically refers to the horizontal distance to the load CG and is typically half the length of the load for symmetrical objects. To illustrate how attachments and load CG’s can affect residual carrying capacity, consider for example that a particular forklift with only forks on the carriage is rated at 5,000 lb capacity @ 24” load center on the data plate. This forklift will only be rated at 1,270 lb when equipped with a particular 8 foot long fork mounted jib boom because the boom adds weight and moves the load center out to 96 inches. In this case the forklift may employ a dual load center capacity rating on the capacity plate indicating a greater lifting capacity (2,750 lb) at a 4 foot load center and a lower capacity (1,270 lb) at the 8 foot load center.
Load Center also Effects Carrying Capacity
Small changes in load center can also greatly affect the carrying capacity. Consider the capacity of the same 5,000 lb forklift with 48” forks and rated at a 24” load center, drops to 3,660 lbs when 72” fork extensions are employed to lift a 6 foot long load.
Where to Check Your Lift Capacity
The main thing to consider is that every forklift has a legible capacity plate that accurately reflects the attachment configuration being used at the correct load center for the load being lifted and contact Professional Forklift Engineering Services at www.forkliftcapacitycalculator.com to check your lift capacity and get a professional engineering (PE) certified capacity rating plate on your forklift today.