Trailer landing legs are a pair of heavy-duty, height-adjustable support legs fitted near the front of an articulated trailer, just behind the bed plate. Their primary purpose is to support the front of the trailer when it is uncoupled from the tractor unit.
When a trailer is parked or being loaded without a tractor attached, the landing legs carry the front-end load and provide stable support. This allows safe loading, unloading and storage without relying on external equipment.
In normal operation, landing legs are usually raised or lowered while the front of the trailer is still supported by the tractor unit. Trailers are typically left uncoupled with the front slightly raised, allowing the next tractor unit to reverse under the trailer and use its air suspension to raise the fifth wheel to the correct coupling height.
During uncoupling, the tractor suspension is often raised first to take the load before the landing legs are lowered until they contact the ground. Once the trailer services are disconnected and the tractor pulls clear, the trailer remains supported on its landing legs. Raising or lowering the legs without a tractor unit present is less common and typically requires the low gear due to the weight involved.
Most trailer landing legs are operated manually using a crank handle with a two-speed gearbox. A low gear provides the mechanical advantage needed when significant front-end weight is still bearing on the legs, while a high gear allows faster movement when the load is already supported by the tractor. Powered (electric) versions are also available and are typically used in high-frequency operations to reduce manual effort.
Landing legs are designed to withstand substantial static loads and are a critical component in safe trailer operation, particularly during coupling, uncoupling and loading activities.
Frequently Asked Questions
What is the difference between compensating feet and rocker feet on trailer landing legs?
Compensating feet pivot to maintain a flat contact with the ground, allowing for slight front-to-back movement as the trailer suspension and brakes settle. This helps spread the load more evenly and improves stability. Rocker feet can also move slightly, but their curved shape means ground contact is much narrower, which limits load distribution and makes them less stable on uneven or shifting surfaces. The choice depends on operating conditions and ground quality.
Why do some trailer landing legs have gears?
Landing legs use a two-speed gearbox to allow controlled movement under different load conditions. A low gear provides high mechanical advantage, allowing the operator to raise the front of the trailer when significant front-end weight is still bearing on the legs. This requires many turns of the handle for only a small amount of movement. A high gear provides faster movement with less resistance and is typically used when the trailer weight is already supported by the tractor unit during coupling or uncoupling.
What happens if I uncouple the trailer without lowering the landing legs?
The front of the trailer will drop to the ground once the tractor unit pulls away. This can cause damage to the trailer structure, landing leg assemblies, airlines, electrical connections or the ground surface, and may make it difficult or unsafe to recouple. In severe cases, recovery equipment may be required to lift the trailer back to a usable height.
Is it possible to tip a trailer if it is only supported at the front on the landing legs?
Yes, but this typically only occurs under specific loading conditions. If heavy, dense loads are positioned towards the very front of the trailer, forward of the landing legs (often around 3.9 metres back from the front), the centre of gravity can shift beyond the support point and cause the trailer to tip. In these situations, it is recommended that the front of the trailer remains supported, either by a tractor unit or a suitable trestle, to maintain stability during loading or unloading.
