Forklift jacks are lifting aids designed specifically to raise forklift vehicles for wheel changes, and are hydraulically actuated by a hand-operated pump. The lifting mechanisms are generally of a scissor arrangement, with the lifting arm equipped with a contact pad notched or profiled to afford positive contact on the vehicle lifting points. The characteristic that sets a forklift jack apart from other vehicle jacks is its low general profile designed to accommodate the low ground clearance typical on forklifts. Forklift jack lifting capacities differ, but the average maximum rating is in the region of 8,000 to 9,000 pounds (3,629 – 4,082 kg). There are many different makes and models of forklift jack on the market, all with differing specifications and capacities, but similar functioning in general.
Forklifts often form the backbone of many large material handling operations and generally log a considerable number of running hours. Due to the small turning circles and repetitive nature of most material handling routes, forklift tire wear is a serious issue for most operators. Changing tires on a forklift is not an easy task though, as the vehicles typically sit low off of the ground and are relatively heavy for their compact size. This requires the use of a specialized jack to lift the vehicles for tire changes. The forklift jack is specially designed to handle both the very low ground clearance and heavy weights involved with lifting these little workhorses.
Most forklift jack types are of a conventional scissor design with two sets flat arms of approximately equal length pinned together in such a way that they can move in the same fashion as a pair of scissors. The opposite lower ends of each pair of arms rest on the ground, with one set typically fitted with steel casters allowing the jack to be pushed around. The other contact points are fitted with a broad foot pad, which affords positive contact on the ground reducing the risk of the jack tipping over during lifting. The upper ends of the foot pad arms are attached with rotating pins to the hydraulic pump body. The upper ends of the caster or lifting arms are equipped with a notched lift pad profiled to afford positive contact with the lift points on the vehicle.
The ram or actuator of the hydraulic pump attaches to the lifting arms near the casters. The jack is typically hand-operated using a pump handle and, when actuated, the ram is pushed out of the pump cylinder under considerable pressure. Due to the fact that the pump body attaches to one set of the jack arms and the ram to the other, this action causes the “scissors” to open, effectively raising the lift pad with each pump stroke. A combination of the mechanical advantage of the hinged arms and the power of the hydraulic pump lends the forklift jack its excellent lifting potential. Once the forklift wheel has been changed, a release knob situated on the top of the hydraulic pump is turned, allowing the fluid to slowly bypass back to the reservoir, thereby lowering the vehicle again.