Friction clutches: with a helical band or equivalent member, which may be

Official title: with a helical band or equivalent member, which may be built up from linked parts, with more than one turn embracing a drum or the like, with or without an additional clutch actuating the end of the band (F16D13/02 takes precedence; {similar slip couplings F16D7/022; similar clutches electromagnetically actuated F16D27/025, F16D27/105} ; similar free-wheel clutches F16D41/20; similar brakes F16D49/02)

F16D13/08 (Friction clutches: with a helical band or equivalent member, which may be) appears on 91 US grants and 61 published applications in this corpus.