Mechanics parts, components and assemblies for power transmission, including bevel gears, particularly straight teeth bevel gears and bevel gears made of metal or plastics, racks and round racks made of metal or plastics, bushes, worm wheels made of metal or plastics, worms and bored worms as well as worm gear units, sprockets and sprocket plate wheels, particularly simplex, duplex and triplex sprockets and sprocket plate wheels, sprockets and sprocket plate wheels made of metal or plastics, sprockets for taper bushes and taper lock sprockets, bolt on hubs for plate wheels, chains, roller chains, slat band chains and sprockets for slat band chains, straight and bent attachment plates, chain tensioners, chain tensioning wheels, chain couplings, friction free guide rails for chains, chain lubricants, belts, particularly timing and toothed belts for power transmission, open end timing and toothed belts, belts with parabolic profile, V-belts, timing and toothed belt backings, timing and toothed belt pulleys, V-belt pulleys, clamping belt plates, belt tensioners, threads, particularly lead screws, threaded nuts, and ball screws and nuts, gears, particularly bevel gear units, shaft-mounted spur gear reducers, screw jacks, and worm gears, couplings, particularly splined shafts and sleeves, splined sleeves, torque limiters, chain couplings, torque couplings, locking torque limiter couplings, flexible couplings, curved-tooth gear couplings, jaw type couplings, jaw type couplings in particular for screw jacks, locking assemblies and trantorques, clamping bushes, taper bushes, bolt on hubs for taper bushes, weld on hubs for taper bushes, cardan shafts, limit switches, three phase motors, linear units