May17

The Truth Behind Rated Capacity and Lift Trucks

Many people are surprised when they find out that the advertised or list capacity of a lift truck (often denoted by model name or number) and its actual lift capacity are not always one and the same. While lift trucks are often sold as a 5,000 lb. model, the actual lift capacity depends on a number of factors including lift height, mast tilt and the presence of attachments. To understand the difference between the listed capacity and rated capacity of a lift truck, it's important to understand the mechanics of the lift truck.

The Function of the Fulcrum

Put in its simplest terms, forklifts operate as levers where the force applied to either side of the fulcrum or pivot point is a function of their relative distance from the fulcrum. Here, an object placed further away from the fulcrum will move faster than object placed closer to the fulcrum. As a result, the force applied to the closer object must be greater as power is a product of velocity and force. On a forklift, the heavy counterweight at the rear is situated further away from the front axle fulcrum than the mast and load, allowing it to act as a counterbalance. For a forklift to lift its full listed capacity, the distance between the load and the fulcrum must remain within an ideal range and at a pre-defined load centre (24" by ANSI standards).

The Impact of Mast Tilt, Lift Height and Attachments

As long as the load is kept at a certain distance from the fulcrum point (as defined by the manufacturer's specifications), the forklift's listed capacity and its actual capacity remain the same. If you increase the distance between the load and the fulcrum, however, a forklift's capacity begins to decrease in relation to the distance between the load and the fulcrum. Since both the tilt of the mast and the overall lift height of a load increase the distance between the load and the fulcrum, both factors reduce the rated capacity of a forklift, also known as down rating or de-rating. This principle also applies to attachments such as telescoping booms and carpet poles, where the additional weight of the attachment and the increased distance between the load and the fulcrum reduce the lift capacity of a forklift.

Helpful Tips

To avoid the safety risks and issues associated with exceeding a forklift's lift capacity, remember the following helpful tips:

  • Consider lift heights, attachments and load centres during the purchase process
  • Purchase a lift truck with a greater load capacity than necessary
  • Ensure specification plates are up-to-date, legible, and accurate
  • Educate operators on the importance of down rating and how to read and understand a forklift specification plate
  • Make sure operators know load weights or purchase a scale to weigh load
  • Make sure specification plates are updated whenever major alterations are made, such as adding an attachment, extra valves, etc.

Share On :

Recent Posts


Join the Conversation

Steve

Thanks for the advice. You'd think that a 5,000 lb. truck is a 5,000 lb. truck, regardless of the brand.

Lucas Liftruck

Hi there, that's exactly why we made this post. Just because a forklift is a "5,000 lb." unit doesn't mean that's its lift capacity. A lot of factors go into it including attachments and lift height.

Leave your comment