If you work with forklifts, you should be familiar with the concept of load center distance.The load center distance is often described as the distance from the vertical face of the forklift tines to the load's center of gravity (similar to the concept of a counterbalance).
Calculating your forklift's load center distance
Manufacturers rate their forklifts to a max weight capacity at a specific load center distance and height. This information is typically found on the data plate of the forklift. Here's an example of the information you'd typically find on a data plate:
- Load Center Distance: 800mm
- Mast Vertical: 2500kg
- Forward tilt 1500kg
- Height: 5500mm
From the gathered data one can determine that the maximum weight the forklift can carry at any given time is 2500kg to a height of 5500mm only if back tilt is applied or as long as the mast is vertical. The load should have a max length of 1600mm (to make the load center distance 800 mm).
Typically, the load center of an evenly stacked load (such as pallets) will sit directly in the center of the load. With this information in mind, if a load is 1600mm in length then its load center will be 800mm.
For the sake of argument, let's say that the forklift's rated load center distance is exceeded. In such an instance the load can only be picked up if it falls well under the maximum rated weight capacity of the forklift. Keep in mind that some forklifts are capable of handling numerous load center distances. With that being said, however, some forklifts are only rated for a single load center distance.
Irregular and unevenly stacked loads
Irregular loads will play a significant role in how load center distance is affected. For example, even if the load is still 1600mm in length, the load center distance of the load will be increased outwards if the weight of the load is stacked opposite of the forklift.
To fix this issue, lift the pallet from the opposite side (if possible). You can also consider restacking the load. Keep in mind that when it comes to restacking, standard loads (such as boxes on a typical pallet) should be possible to accomplish. Irregular loads (such as heavy machinery overhanging on a pallet), may not be able to be restacked. In such an instance take extra precautions and ensure the load is well under the weight capacity.
Two more factors to consider: Forklift tines not fully inserted and Long Pallets
Load center distance can be significantly affected by not fully inserting the full length of a forklift's tines into a pallet before lifting and/or when using longer (or irregularly sized) pallets.
You'll want to avoid these scenarios whenever possible, but sometimes such situations are unavoidable in modern day workplaces where trucks are regularly loaded or when pallets of various sizes are used. To manage such loads properly, ensure the capacity of the load itself falls within the forklifts maximum rated capacity.
Sometimes you'll have little to no choice but to lift loads that exceed your forklift's load center distance regularly. In that case, your forklift must be rerated by either an authorized forklift specialist or the manufacturer to help determine your forklift's maximum safe lifting capacity at extended load center distances.
How does tilt affect load center distance?
Tilt can greatly affect your forklift's load center distance. This is a factor that many forklift operators often overlook.
Be mindful that tilt doesn't play a major role when a forklift is lifting a load at ground level as the effect to the load center distance is negligible at best. However, adding height to the equation will significantly affect the load center distance (this is especially the case with forward tilt).
When a load is moved forward and away from the forklift itself, the center of gravity of the load center will fall beyond the recommended load center distance. Thus, even if the forklift is handling a load that falls within its maximum lifting capacity, the forward tilt will reduce its overall lifting capacity. Because many forklift operators are unaware of this fact, tip overs are a common occurrence.
This is only for forward tilt, however. When there is back tilt, the load center distance is reduced thus adding more stability. Despite the added stability, it's not recommended to use fullback tilt to carry loads at significant heights. That is because the load will need to be returned to mast vertical before it can be stacked. Dropped loads and tip-overs can become a danger if the load is moved too quickly.
All attachments on a forklift must be approved by either a forklift specialist or the manufacturer. Your forklift's lifting capacity will also have to be rerated due to the added attachments, as these may affect your forklift's load center distance.
Attachments that have been known to affect a forklift's load center distance (and lifting capacity) includes the following:
- Fine tine extensions
- Drum lifters (claw, beak or clamp)
- Carpet spikes
- Much more
- Always avoid lifting a load if your forks aren't fully inserted. Not only can you drop the load, thus damaging the goods, but the added load center distance will ultimately reduce the lifting capacity of your forklift. You might even run the risk of breaking apart pallets carrying heavy loads if the forks aren't fully inserted.
- Keep in mind that using side-shift will have no affect on the load center distance. However, the load's center of gravity will shift sideways which can increase the chances of a tip over. This is especially the case if you're turning when the forks are raised or when turning too quickly.
- Avoid lifting a significant load at height with forward tilt. This can greatly increase your chances of forward tip over. You should also be careful with light loads as the chances of the load slipping off and falling (thus potentially damaging the goods within) are heightened. Both instances occur due to the fact that the load center distance is too great.
Featured Image Credit: MSGT JOSE LOPEZ JR / Released to Public Combined Military Service Digital Photographic Files
In Post image credit: SrA Justin Wright [Public domain], via Wikimedia Commons