A handcar is a small rail vehicle moved by human power, usually used on maintenance tracks or heritage lines. It typically has a simple frame and a pumping or lever mechanism that converts human motion into wheel movement.
In cyber security, a handcar is a useful example of a physical machine that depends on accurate digital information. If a CAD file, measurement set, or fabrication profile is altered, the finished part may fit poorly or fail to move safely. Attackers can target design files, maintenance records, or build settings to introduce defects, while defenders protect these assets with access control, versioning, checksums, and test assembly. The term matters because modern maintenance and manufacturing often rely on trusted data as much as trusted hardware.