communicate rotational motion therebetween when assembled first clutch 60 is mounted on nonthreaded portion 412 between indicator bearing 55 and threaded portion 410 first clutch 60 permits slippage between rod 40 and first cylindrical member 20 when rotation occurs in a first direction and communicates rotation therebetween in the second direction second clutch 70 identical in structure to first clutch 60 shown in fig6 has an outer periphery 702 dimensioned to fit sufficiently tightly within widest section 340 of second cylindrical member 30 that rotational motion can be communicated therebetween second clutch 70 further has an inner diameter 740 dimensioned to engage threaded portion 410 of rod 40 and move longitudinally therealong the directionality of second clutch 70 permits locking between rod 40 and second cylindrical member 30 when rotation occurs in the first direction rotation in the second direction causes rotational slip thus allowing linear movement between rod 40 and member 30 when the device 10 is fully assembled rotation in the second direction causes second clutch 70 to move along threaded portion 410 of rod 40 toward second end 404 and consequently threaded portion 410 moves in a longitudinal direction out of threaded section 336 of bore 308 in second cylindrical member 30 such relative longitudinal movement serves to push second cylindrical member 30 out of the bore 208 of first cylindrical member 20 elongating device 10 in detail clutches 60 and 70 comprise cylindrical clutch housing 702 clutch cage 704 end cap 706 four clutch springs 708 and twelve clutch rollers 710.