During the Top Roll uprighting, the tow truck lifts the casualty near an upright position. Extending the boom and operating the winch at the same time can help keep the lifting vertical above the casualty. The operator will observe that as the casualty is lifted into an upright position, it’s weight is transferred off of the ground and begins moving over to the opposite side of the casualty. At some point when the center of gravity reaches the balance point, the load will be transferred from the lifting side of the rigging over to the control side of the rigging. At this point the operator should quickly lower the casualty to the ground. This is easily done by telescoping the boom inward and lowering the boom to the ground simultaneously. Retracting the boom and lowering the boom is the quickest way to lower the casualty to the ground. Once the casualty is on the ground the rigging can be disconnected and the tow truck be placed back in service.
Watch the animation as this recovery process has been placed in the service. You’ll see that the lifting line that lifts the casualty towards its wheels, the weight is transferred to the controlled side rigging and the casualty is lowered carefully to the ground.