Coilable tape rule with shifting hub, reel assembly therefor, and method of assembling

A cartridge for a power returnable coilable rule comprising:

• A. a reel having a cylindrical core, annular end walls of greater diameter than said core portion to provide an axially extending passage therethrough, said reel having a hub seating recess in the outer surface of one of said end walls about said passage, said core forming an annular chamber open at its inner periphery about said axially extending passage;
• B. an axially shiftable hub having a barrel in said passage of said reel and a flange adjacent one end seated in said seating recess, said hub flange and said hub seating recess being cooperatively configured and dimensioned for frictional engagement of said hub in said recess, said hub flange releasably locking in said recess to prevent relative rotation therebetween, said hub being freely slidable axially and rotatable in said reel passage upon disengagement of said flange from said recess, said hub having an axially extending passage therethrough to receive a shaft of a rule casing in which said cartridge is placed;
• and
• C. a recoilable spring coiled within said core of said reel and having its inner end engaged with said barrel, said hub being shiftable axially to seat said hub flange in a cooperating recess in the rule casing in which said cartridge is placed to effect simultaneous disengagement from the reel and engagement of the spring with the rule casing.

In the method of making a coilable rule, the steps comprising:

• A. forming a reel having a cylindrical core, annular end walls of greater diameter than said core portion to provide an annular chamber thereabout, and an axially extending passage therethrough, said reel having a hub seating recess in the outer surface of one end wall about said passage;
• B. seating in said passage of said reel the barrel of an axially shiftable hub which has a flange at the end thereof adjacent said one end wall, said flange and said hub seating recesses being cooperatively dimensioned and configured to snugly seat said flange, and pressing said flange into said recess to lock said hub against relative rotation;
• C. engaging one end of a recoil spring with said barrel of said hub and coiling it within said core of said reel;
• D. placing said reel subassembly in a casing section having a cooperatively configured hub seating recess in its inner surface;
• and
• E. axially shifting said hub to unseat said hub flange from said seating recess of said reel and seat it in said hub seating recess of said casing section to permit said reel to rotate about said hub and relative to said casing section.