Safety When Driving Equipment onto Trailers

Richard L. Parish, PhD, PE

Many turf professionals move mowers and tractors from one job site to another using trailers or trucks. Loading equipment onto trailers and trucks presents a safety challenge. Loading the right way can reduce the risk of overturn and operator injury.

Overturn Hazard: Most mowers and tractors used by turf professionals have a low center of gravity and are not easy to overturn, but an overturn is still possible when driving up or down a loading ramp onto a trailer or truck. Overturns primarily occur because of the torque on the drive wheels. When driving up a slope, the load on the uphill axle is decreased and the load on the downhill axle is increased. If the downhill axle is the powered axle, the torque driving the axle will tend to rotate the machine around that axle. The problem can also occur when backing down a loading ramp. If the brakes are applied while descending, the brake torque on the driving axle can cause the machine to rotate about that axle.

Drive Axle Up! The easy way to avoid this problem is to keep the drive axle uphill while loading and unloading. If you keep the drive axle uphill, any tendency to overturn will lift the driving tires, causing the tires to lose traction, and thus immediately stop the overturning tendency. With a tractor, the rear axle is the driving axle so you need to keep the rear of the tractor pointed up the ramp. Always back a tractor up a ramp and drive down forwards. The same situation is true for a mid-mount ZTR mower. The rear axle is the driving axle, so back up the ramp and drive down. With a front deck rider, the situation is different. The front axle drives and the rear axle steers, so you should drive up and back down.

Remember; the critical point is to keep the drive wheels of your tractor or mower on the upward side of the steering tires.