Trucker's (Haymaker's, Harvester's, Lorry) Hitch Details
Use: The Trucker's Hitch (Lorry Knot, Haymaker's Hitch, Harvester's Hitch) (ABOK # 2124, p 344) has the distinctive feature of providing a mechanical advantage when being tightened. The variety of names for this hitch is a tribute to its widespread use. It is a valuable knot - particularly for securing loads or tarpaulins.
3:1 Purchase: The arrangement of line provides a theoretical 3:1 purchase. However, rope is running over rope with considerable friction. In practice the mechanical advantage is much less, may be more like 1.6:1. However, hauling on the line can be surged and then the friction is an advantage as it helps hold the gain while the end is secured. The theoretical 3:1 gain assumes that the lower attachment point is fixed and the upper point is being moved.
Structure: There are several variations in widespread use. The common factors are: a knot to create an eye at the top; the three to one purchase; and a hitch to secure the end.
Several knots may be used at the top including the Directional Figure 8 (used in the animation, the
Slip Knot, the
Bowline on a Bight, the
Alpine Butterfly, and, simplest of all, a mere twist of the rope to create the loop.
The final hitch can be a Rolling Hitch which has the advantage that it facilitates adjustment. Whichever hitch is used, the rope may be passed around the lower hook a second time before being secured.
Classical Structure: Early descriptions show a Figure 8 Loop used to form the initial loop. However, this tends to be hard to untie after heavy loads and the version in the animation is preferred.
Taking the Strain: After the free end is threaded and tightened, the load can be taken temporarily by pinching the rope where it passes through the loop. The other hand is then used to form the two Half Hitches.
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