Spanset Australia - World leaders in lifting, load restraint, height safety, and 4WD recovery equipment

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Load Restraint Guide

G Forces

Loads during transport are subjected to G forces when cornering, stopping, accelerating, and in emergencies. This can lead to various movements of the load, which may create serious hazards to both the driver and other road users. Shifting loads can cause serious destabilisation of the vehicle, or penetration of the load through the cabin, particularly in emergency braking situations. These G forces must be taken into account when specifying load restraint equipment.

Other influencing factors to be taken into account are aerodynamic forces, transporting loads over hills and undulating terrain and the friction co-efficient between the load and the surface on which it is transported.

The predicted forces for the various modes of transport can be seen below.

Restraint methods for different applications


TIEDOWN This is used to maximise the friction between the load and the deck (friction co-efficient). Tiedown lashings rely on the pre-tension capability of the assembly and not on the overall strength of the system ie: if the system is capable of exerting sufficient pre-tension it is strong enough for the application.
DIRECT With direct lashings the assembly strength is used to restrain the load, sometimes in several directions, with less emphasis placed on friction values. The angles of the straps can lead to a reduction in overall assembly strength.
COMBINATION It is sometimes necessary to combine both direct and tiedown methods to particular loads. This utilises both the strength of the direct lashing and the clamping force of the tiedown.
BUNDLED This method is ideally suited to loose pipes or lengths of steel etc. Because of the low friction value between the individual product it is almost impossible to effectively lash these directly to a truck body. Pre bundled product becomes a single unit which can then be lashed to a vehicle.
The aim of an effective lashing is to apply a downward force on the load in order to increase the friction between the product and the tray. This works in the same fashion as a large "G" clamp locking the load down and therefore preventing forward movement.

General Warnings and Instructions