Figure 5-7.—Mechanical advantage and change of direction (winching).
Figure 5-8.—Winching by change of direction
lifting, and towing) of the trucks to complete the
recovery.
To upright an overturned truck with a wrecker truck,
Overturned Truck
Figure 5-8 shows a mechanically disabled 2 1/2-ton
truck nosed off a narrow road in such a way that the
wrecker cannot be positioned directly behind the
vehicle. You may notice that the winch cable is not
running in a direct straight line with the winch. On a
normal winch, this angle causes the wire rope to wind
off the side (flange) of the winch drum; however, the
wrecker winch has a level winding device that offsets
the difference. Other vehicles with winches do not have
this device.
5-9
you should use a sling method of attachent, because a
pulling force applied to only one point of the frame can
result in a bent frame. A sling lifting attachent is made
up of either two utility chains or two 1-inch fiber ropes.
The sling ends are attached to the front and rear lifting
devices on the high side of the overturned truck. Then
the winch cable is attached to the center of the sling. A
holding force is required to prevent the overturned
vehicle from crashing onto its wheels. The holding force
