Types of Lift Trucks
Counterbalanced Lift Trucks
Counterbalanced lift trucks are used extensively throughout industry and are available in various capacities. The counterbalanced lift truck is an all-purpose lift truck that is adaptable to most operations and operating conditions.
The Industrial Truck Association has separated the numerous types of lift trucks into seven classes. However, since this blog is about counterbalanced lift trucks, only Classes 1, 4 and 5 will be discussed.
Electric Motor Rider Truck
One of the more common counterbalanced lift trucks is the electric motor rider truck or Class 1. The Class 1 lift truck is designed for indoor use and is available in either sit-down or stand-up mode. Most sit-down models have four wheels; however, a three-wheel version is available for more maneuverability. The stand-up lift truck has three wheels, allowing it easy access to narrow aisles, and allowing for the loading and unloading of boxcars and trailers. This lift truck is powered by a lead acid battery that acts as a counterweight when lifting heavy loads.
Internal Combustion Engine Rider Truck
The combustion engine lift truck is more commonly used than the electric, battery powered lift truck, as it can be fuelled by gasoline, diesel or propane. This lift truck can be equipped with solid or cushion tires (Class 4) for mainly indoor work or pneumatic (air-filled) tires (Class 5) for outdoor applications where greater traction is required.
The Main Parts of a Lift Truck
Lift trucks have a number of main parts; some moving and some stationary. These include:
- The cabin and overhead guard.
- The counterweight.
- The drive wheels and steering wheels.
- The carriage and backrest.
- The mast (or upright channel).
- Tilt cylinders and single-action lift cylinders.
- Forks and other lifting attachments.
Static and Dynamic Conditions
Lift truck balance is affected by both static and dynamic conditions. Static conditions include the size and shape of the load, the position of the load on forks, the lift height, the amount of tilt, and tire pressure. Dynamic conditions include acceleration, speed, braking, ramps and other uneven surfaces.
Centre of Gravity and Load Centre
Lift trucks operate on a lever principle, much like a teeter-totter. The front wheels act as the fulcrum or pivot point, balancing the load on one side with the counterweight on the other. If this counterbalance capacity is exceeded, the lift truck will tip forward.
The capacity rating refers to the maximum weight that can be safely raised and moved by a lift truck, while taking into consideration a specific load centre being raised to a specific height. All lift trucks are required by law to display a legible capacity plate. A capacity data chart is used to determine the lift truck’s capacity in relation to its load centre. When using any lift truck, always ensure the floor will support the weight of the load.
Overloading and Improper Loading
If the load exceeds the rated capacity, the steering wheels will come off the ground and the load will tilt forward. This can also happen if a rated load is placed too far forward of the fulcrum point or if the lighter part of the load is closest to the backrest.
Stability and Centre of Gravity
With no load on the forks, the centre of gravity will be located towards the rear of the truck. The lift truck has moving parts and therefore its centre of gravity will move as well. When the lift truck is carrying a load, the truck and load have a combined centre of gravity. The stability of the lift truck is determined by the location of the centre of gravity. The stability and the combined centre of gravity are affected by the size, weight, shape, and position of the load. Tilting of the mast will also have an effect on stability.
Lift truck operators must be trained in the operation of the specific lift truck they will be using on the job. The lift truck operator’s main responsibility is to operate the lift truck safely, according to training, company policies and procedures, and manufacturer’s specifications. Unsafe operation of a lift truck could result in death or injury to the operator or others, as well as damage to the lift truck or property.
NORCAT offers Lift Truck Awareness training online for $29.95. This program provides the theory portion of training, which lift truck operators require prior to practical training.