landing gear
The bipod stand found near the front end underneath a truck trailer, used to keep the trailer level when not attached to a tractor truck.
landing gear: the trailer's leg when the tractor uncouples
Landing gear is a mechanical support system mounted on the underside of a semi-trailer near its front, designed to hold the trailer level and stable when it sits unhitched from a tractor unit. When a trailer is parked or waiting for pickup, the landing gear lowers on hydraulic or manual jack screws to rest on the ground, transferring the trailer's weight from the kingpin coupler to a solid foundation and preventing nose-dive or tipping.
The gear consists of two vertical legs or posts, each fitted with a screw mechanism that can be cranked up or down, typically by hand crank or powered pump. Standard landing gear extends roughly 12 to 24 inches and must support trailer weights ranging from 10,000 to 30,000 pounds depending on trailer type and load. The legs are usually welded or bolted to a frame beam that spans the trailer's width, distributing load across both support points evenly.
Variants and Operation
Older trailers use manual landing gear with a direct mechanical crank handle that rotates a threaded shaft, lowering or raising the foot pads. Modern units employ air or hydraulic power packs that drive the jacks remotely, either from the tractor's air supply or an independent compressor mounted on the trailer itself. Some power systems integrate with the tractor's electrical system for smooth synchronized lowering during uncoupling.
Rust, bent legs, and seized or stripped screw threads are common field failures, particularly on trailers exposed to salt or moisture. A frozen or broken landing gear becomes a operational liability: the trailer cannot be safely parked or loaded, and it becomes a liability hazard if it shifts or collapses under load. Regular greasing and inspection of the screw mechanisms and pads helps prevent damage and keeps the system functional.
The term "landing gear" borrows from aviation, where similar retractable support structures stabilize aircraft on the ground. In trucking, the name reflects the gear's job: it allows the trailer to "land" safely without the tractor, sitting level on hard ground rather than resting at an angle on the kingpin or tipping sideways. It is essential equipment on any trailer that operates independently of a tractor for more than brief periods.