Operating a loaded lift truck on a ramp introduces heightened hazards due to shifting forces. The danger stems from the change in the lift truck’s center of gravity as it navigates an incline, significantly increasing the risk of a lateral or longitudinal tip-over. Strict safety protocols are mandatory for operators to maintain control and stability when ascending or descending a grade. These procedures ensure the combined weight of the machine and its load is managed safely.
Understanding Lift Truck Stability on Ramps
Lift truck stability is defined by the stability triangle, an imaginary area formed by the two front wheels and the center point of the rear axle. The machine stays upright as long as the combined center of gravity (CG) of the truck and load remains within this triangle. While the CG is stable on flat surfaces, a ramp dramatically changes this equilibrium, threatening the truck’s longitudinal stability (resistance to tipping forward or backward).
Navigating a ramp causes the combined CG to shift toward the downhill side, moving it closer to the edge of the stability triangle. Driving up a ramp shifts the CG backward, and driving down shifts it forward. This increases the likelihood of a tip-over if the load is positioned improperly, especially on grades exceeding 10 percent. Operational rules are designed to counteract this destabilizing effect and maintain the CG within the safe zone.
Pre-Operation Checks Specific to Ramp Use
Before ascending or descending a ramp, specific checks must be completed to ensure safety. The ramp must be inspected, starting with verification of its load capacity rating, especially for portable yard ramps or dock plates. The surface needs to be free of debris, such as loose gravel, oil, water, or ice, which could compromise tire traction and lead to skidding.
The load requires careful attention before approaching the incline. It must be securely centered and stable on the forks, and tilted back against the carriage to prevent shifting during travel. Operators must consult the truck’s data plate to ensure the combined weight of the load and the truck does not exceed the ramp’s rated capacity.
The Golden Rule: Maintaining the Load Uphill
The most fundamental instruction for driving a loaded lift truck on a ramp is keeping the load upgrade, meaning the forks and load must always face the uphill direction. This rule applies whether the truck is ascending or descending. When the load is oriented uphill, gravity keeps it pressed securely against the mast and carriage, preventing it from sliding off the forks.
To follow this rule, the operator must drive forward when ascending a ramp. Conversely, the operator must drive in reverse (back down the ramp) when descending, ensuring the load remains pointed toward the higher ground. This procedure is required by safety regulations, such as OSHA standard 29 CFR 1910.178(n)(7)(iii) for grades exceeding 10 percent. Maintaining the uphill orientation of the load is the most effective way to preserve longitudinal stability.
Procedure for Driving Up a Ramp (Loaded)
When ascending a ramp with a load, the operator must drive forward slowly, keeping the load facing the incline. The forks should be raised only enough to clear the ramp surface (typically 4 to 6 inches) to prevent scraping and keep the combined center of gravity low. The mast must be tilted slightly back to reinforce the load’s grip against the carriage, countering its tendency to shift backward.
A constant, slow speed is crucial throughout the ascent. The operator must avoid sudden changes in acceleration or direction, as rapid acceleration causes instability and sudden braking can cause the load to shift forward. Maintaining a steady pace prevents momentum from destabilizing the truck. If the load obstructs the forward view, a spotter must be used.
Procedure for Driving Down a Ramp (Loaded)
When descending a ramp with a load, the operator must drive in reverse, backing down with the load still facing the uphill direction. This ensures the load remains on the uphill side of the truck, preventing it from sliding forward off the forks. The operator must turn their head to face the direction of travel to maintain clear visibility down the ramp.
To control the descent, the operator should primarily use the truck’s engine for braking, known as compression braking, which offers smoother deceleration. Relying solely on the foot brake, especially with a heavy load, can lead to excessive heat, brake fade, or sudden skidding. The descent must be executed at a constant, slow speed, maintaining a safe distance from the ramp’s edge to avoid a lateral tip-over.
Critical Safety Considerations for Ramp Driving
Several operational constraints must be strictly followed when driving on any incline to mitigate the risk of accident. A lift truck must never be turned while on a ramp or incline. Any lateral movement will shift the center of gravity outside the stability triangle and lead to an immediate tip-over. All directional adjustments must be completed on flat, level ground before approaching the grade.
Operators must maintain a significant distance between their truck and any other vehicle on the ramp to prevent collisions. Speed must be kept to a minimum, allowing the operator time to react to any change in the environment or loss of traction. The operator should sound the truck’s horn when approaching the crest of the ramp or any blind spot to alert others.