Truck Tipping Forward

Operators must be taught the principles of the stability triangle. This principle can be compared to a seesaw. If one end of the see-saw has a heavier load than the other, the heavy load will go downward. The determination of whether an object is stable is dependent on the moment of an object at one end of the system being greater than, equal to, or smaller than the moment of the object at the other end of the 

The stability triangle is illustrated by using an invisible dot situated within a triangle under the lift truck. 

There are several additional situations where operators could lose stability. 

The lateral stability of the lift truck is determined by the position of action in relation to the stability triangle. This is represented by a vertical line that passes through the combined center of gravity of the vehicle and the load. When the vehicle is not loaded, the location of the center of gravity of the truck is the only factor to be considered in determining the stability of the truck. 

As long as the line of action of the combined center of gravity of the vehicle and the load falls within the stability triangle, the truck is stable and will not tip over. The truck becomes unstable and may tip over if the line of action falls outside the stability triangle. 

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A-3.2. The longitudinal stability of a counterbalanced powered industrial truck depends on the vehicle s moment and the load s moment. In other words, if the mathematic product of the load moment (the distance from the front wheels, the approximate point at which the vehicle would tip forward) to the load s center of gravity times the load s weight is less than the vehicle s moment, the system Is balanced and will not tip forward. However, if the load s moment is greater than the vehicle s moment, the greater load-moment will force the truck to tip forward. 

When a lift truck tips over onto its side like the incident shown in Figure 10-1, or goes forward or backward off a dock, the operator can be ejected. When this occurs the operator can easily be crushed by the... 

The capacity of each forklift is identified on the manufacturer s data plate the load center is also identified on the nameplate. Load centers are usually 24 inches forward from the mast. If a load is within the capacity of the lift truck but its load center is greater than 24 inches, the lift truck may not be able to safely handle the load. Overloads are another problem for lift trucks. Damage to chains, truck components, and other truck parts can easily occur if overloaded. The truck can tip forward, as demonstrated in Figure 10-13, with the counterweight raised off the floor, which could injure employees and damage property. 

A load that is heavier than the rated capacity of the lift truck will cause the lift truck to tip forward. The distance between the backrest to the center of the load determines if a load can be lifted safely. If a load is within the capacity of the lift truck but too far out on the forks, the lift truck can tip forward. Forks must be placed completely under a load and the mast must be tilted back for load stabilization. When the load moment is greater than the vehicle moment, the greater load moment will force the truck to tip forward. 

The training of operators must include classroom interaction and the use of visual aids. Many of the various details of lift truck movement such as tipover, tip forward, counterbalance, stability triangle, lateral and longitudinal stability must be discussed. Trainees must know each model s specific details for operation. Couple this with the different kinds of lift trucks counterbalance, narrow-aisle, walkies, stock-chasers, etc., and it s obvious that there are many details involved in operating a powered industrial truck. 

After positioning the device, the truck is slowly driven forward (creep speed) and the maximum deflection is recorded as the tyres pass the tip of the arm. The vehicle continues to move forward for some metres (approximately 7 more metres) and the minimum deflection is recorded. 

In a study of 804 injuries and incidents involving narrow-aisle lift trucks, tipover accounted for 127 of the reported claims, or 16 percent of the total. In the case of a narrow-aisle truck tipover incident, the truck can tip three different directions forward, rearward, and onto its side. Of the 127-tipover incidents, 64 percent involved tipover onto the side of the lift truck, 12 percent were forward tipovers, and 11 percent were rearward tipovers. Those that occurred in an unknown direction accounted for 13 percent of the total incidents. 

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