Power returnable coilable rule cartridge and coil rule assembly employing same

摘要

A power returnable coilable rule employs a cartridge having a hub rotatably seated and trapped in apertures in the end walls of the spool. The hub has a multiplicity of tabs at each of its ends which interlock with bosses on the inside surfaces of the outer casing end walls so as to prevent relative rotation thereof. The power spring is attached at its inner end to the hub and at its outer end to the inner end of the coiled measuring blade. Prior to assembly in the rule casing, a retainer clip secures the blade and spring in predetermined condition on the spool. This clip has an arm overlying a spool end wall with means adjacent its inner end interengaged with the tabs of the hub, and a flange at its outer end which depends along the outer coil of the blade and interengages with the tape hook so that the opposing forces on its ends produced by the coiled spring maintain the retainer clip in assembly.