A line of torque-limiting safety couplings from Rimtec Corp., West-mont, Ill., protects from crashes or runaway drives. The zero-backlash couplings are for high-end servopositioning systems. An integral, digressive Belleville spring disengages even dynamic digital drives at the speed of 2 to 4 msec following an overload signal, and then reengages at the precise angular position. Precision roller guides are said to have a higher contact surface compared to conventional ball guides for back-lash-free torque transmission in both directions of rotation. The couplings come in direct and indirect-drive versions. Direct-drive couplings are available in torque ranges from 9 to 14,160 lb-in. on shafts from 0.25 to 3.5 in. Indirect-drive couplings are available with torque ranges from 265 to 14,160 lb-in. on shafts from 0.5 to 3.5 in.