Retractable rolled flexible steel measurement rule - has new spool and spring held by clamp enabling easy replacement when original is worn

摘要

A pocket flexible steel measurement rule in which the rule and spring can easily by replaced when they are damaged or worn out is presented. The rule is mounted in an outer casing consisting of two matching shell elements which have a slot or guideway through which the rule can be drawn and a thumb operated brake button. The rule is wound on a spool carrying an internal wound spring (12) and rotates a shaft (28) which is mounted in the outer shells by means of two square section projections. A new spool and spring are provided with a holding clamp (52) which retains the rule and maintains the spring (12) state. The old spool can be renewed and thrown away, the new clamped spool inserted in one shell unit, the clamp (52) removed and the other shell screwed on to the first.