Torque-limiting bit for driving bolt - may be length of hexagonal section bar with circumferential groove or rupture neck dividing it into two

摘要

The torque-limiting adaptor (10) transmits rotary drive from a spanner to a bolt. In its simplest form it comprises a length of hexagonal section bar (10) divided into two (11,12) by a circumferential groove (13) or neck. One piece (11) may be gripped by a spanner while a second (12) engages a socket in a bolt head. The groove (13) has specific geometry for the two pieces (11,12) at a specific torque. One piece may have a nib (14) so that it locks in a nut socket to indicate its having been driven. Hexagonal heads (15,16) with a flange (20) and with or without a socket (17) may be built into one piece (11), similar formations may be built onto the other and round section heads may have a square section socket or spigot.