Truck & Trailer Door Hardware Explained: Door Gear, Locks, Hinges and Seals
Updated 2026-10-28 · Aurex trade counter, Campbellfield VIC
Short answer: rear doors on vans and trailers are usually locked by door gear, a vertical bar with cams at each end turned by a lever handle. Side doors and toolboxes use paddle locks. Doors hang on strap hinges, are held open by retainers, and are sealed by PVC or rubber profiles. To replace any of them, measure the old part and match its size and handing.
Door gear and cam locks
Door gear is the vertical locking bar on a rear door. A cam at each end engages a keeper on the door frame when the lever handle is turned, pulling the door tight against its seal. Size is set by the outside diameter of the bar. Our range covers 22mm (light commercial vans and bodies), 27mm (truck and trailer doors) and 34mm (heavy-duty trailer and semi doors).
- Measure the bar's outside diameter, not the handle.
- Check the handing: L and R versions mirror each other to suit the left and right doors.
- A cam gear sub-assembly without a handle suits workshops fitting their own handle or reusing a good one.
Paddle locks and handles
Paddle locks sit flush or recessed in a door panel and are opened by lifting the paddle. They suit toolboxes, canopies, service bodies and side doors. Stainless versions suit wet or wash-down conditions, and powder-coated steel versions suit general use. Some recessed kits operate locking rods on rear trailer doors. In our range, the 152 × 320mm stainless kit suits doors with 16mm rods.
Hinges: weld lug or bolt lug, steel or stainless
Rear door strap hinges come with a weld-on lug, welded to a steel frame, or a bolt-on lug for bodies where welding isn't practical. Stainless steel (304) resists corrosion on refrigerated and wash-down bodies, and zinc-plated or raw steel suits general freight bodies. Match the length and hole pattern to the hinge you're replacing.
Door retainers and hold-back catches
A retainer holds an open door back against the body so it can't swing in the wind while you load. Choose the arm length to suit the door width and how far it opens, and the material to suit the body: zinc-plated steel, aluminium-bodied for lighter bodies, or stainless for refrigerated vans.
Door seals
Seals close the gap between door and frame to keep out weather and dust and, on refrigerated bodies, to hold temperature. Pick the profile by the gap it has to close. With the door shut, measure the gap, then the depth of the face the seal mounts to. Wider profiles suit wide-gap rear doors. Corner tabs finish the seal at the door corners.
Measuring for a replacement
- Lay the old part on a flat surface and photograph it beside a tape measure.
- Note overall length, hole centres and hole diameters, and for door gear the bar diameter.
- Note which door it came from (left or right, rear or side) and which way the door opens.
- Send the photos and measurements to the counter, and we'll match the part before dispatch.