GB942381A - Improvements in tape-measures - Google Patents

Abstract

942,381. Measuring-tapes. NATIONAL RESEARCH DEVELOPMENT CORPORATION. May 25,1960 [May 30, 1959; Feb. 4, 1960], Nos. 18513/59 and 4076/60. Heading G1M. The measuring tape 22 is wound on a reel 1 and can be locked in an extended position by a spring-loaded eccentric member 25. Two spring bands 14,15 are normally accommodated on spools 16 but may be wound on to a bobbin 13. This bobbin 13 has a radially toothed face 10 which is spring urged into engagement with a similar face 3 on the tape reel 1, and the engagement may be released by depressing a button 8. In use, the button 8 is depressed and the tape pulled out nearly to the length it is desired to measure. The button 8 is then released so clutching the bobbin 13 and the reel 1 together. Final drawing out of the tape 22 then winds the bands 14,15 on to the bobbin 13 and this is stated to produce a constant returning torque on the reel I so that long distances may be measured with the tape under a constant tension and allowance may be made for the sag in the tape by providing different zero marks which are used according to the length being measured. Pawls 17,17a urged into notches 18 are used to prevent the bands 14,15 from unwinding or being wound up too far. In a second embodiment, Fig. 4 (not shown), the bobbin 13 is clutched to the reel 1 when the winding handle is in its inoperative position e.g. when the tape is being pulled out. A hydraulic damper is used to limit the speed at which the spring bands are retracted. The tape may be provided with a hemispherical knob for measuring into corners bounded by three planes, a similar knob being provided on the measuring face 24 of the casing. The rewind handle may be connected to the tape reel by a constant-torque coupling, the tape being run out freely and the excess reeled in until the tension is correct when the rewind handle will slip.