Leg-Safe Landing Leg Safety System

Landing leg safety and trailer drops

A trailer "drop" occurs when a driver uncouples the tractive unit before the landing legs are lowered sufficiently. Once the tractive unit pulls away, the front of the trailer is no longer supported and drops under gravity until the landing leg feet strike the road or bay surface.

This situation most commonly occurs during the de-coupling process when drivers are tired, distracted or working under time pressure. The consequences can be significant, affecting the trailer structure, the ground surface and the safety of the surrounding area.

Impact forces from a trailer drop

Don-Bur carried out an assessment based on an average 26,500kgs load on a standard 13.7m long trailer. Approximately 8,050kgs of that load is positioned forward of the landing legs.

If the trailer drops just 40mm before impact (landing leg travel is typically 250–300mm), the kinetic energy generated is equivalent to a weight of approximately 64,356kgs. Forces of this magnitude can deform landing leg feet, damage bay or road surfaces and potentially damage the trailer chassis.

Less obvious, but potentially more serious, is the risk of structural stress within the trailer neck. Repeated or severe impact loads can introduce distortion or stress fractures which may later require significant repair work.

Leg-Safe landing leg safety system

Leg-Safe is a Don-Bur engineered safety system designed to reduce the risk of trailer drops during uncoupling. The system monitors both the trailer air connection and the position of the landing legs, warning the driver if the legs have not been lowered to a safe position.

A pressure sensor monitors the red emergency air line. When the red line is disconnected during uncoupling and pressure drops, the Leg-Safe system becomes active. A positional sensor mounted on the landing leg then assesses the height of the leg relative to the ground.

If the landing leg is not within approximately 10mm of the ground surface, Leg-Safe triggers audible and visual warnings to alert the driver before the tractive unit pulls away.

• Helps ensure landing legs are lowered before uncoupling
• Reduces the risk of trailer structural damage
• Helps prevent damage to bay floors and road surfaces
• Encourages safe coupling and uncoupling procedures
• Reduces health and safety risks associated with dropped trailers

Optional system extensions

Additional sensing options can be incorporated to support different operational requirements.

• Confirm landing legs are lifted before transit
• Provide additional feedback to encourage correct operating procedures