A Road Diamond Load Lock Winch (often called a sliding winch, load-lock spool or cargo winch) is a compact mechanical drum and ratchet assembly used to tension straps, webbing or wire rope for cargo restraint on trucks, trailers and material-handling equipment. It’s built to mount into trailer/vehicle fittings (L-track, D-rings or bespoke brackets) and gives a small, rugged means to take up slack and lock a cargo strap in place.