Technical Description: A box spanner is a specialized, thin-walled socket wrench consisting of an elongated, hollow steel tube with a six-point or twelve-point hexagonal profile at its ends. Its hollow center allows it to slip completely over long, protruding bolt threads to reach deep-set nuts in restricted spaces. The body is cross-drilled near the ends to house a removable steel crossbar, known as a tommy bar, which serves as the handle.
Operational Principle: The tool converts manual horizontal leverage into rotational torque to handle fasteners in narrow cavities. After inserting the tommy bar through the cross-drilled holes, the operator lowers the hollow tube into the recess and seats it squarely over the nut or bolt head. Turning the tommy bar clockwise tightens the fastener, while turning it counter-clockwise loosens it, with the hollow body seamlessly accommodating the rising thread during extraction.
