7 Hydraulic, electric and air driven rotary dressing apparatus, namely, dressing tools for grinding wheels; dressing tools for peripheral dressing of plunge grinding wheels; dressing tools for end cutter dressing of internal grinders and camshaft grinders; dressing tools for Computer Numerical Control (CNC) profile dressing; dressing tools for dressing of centreless grinders, plain 90 degree plunge grinders, angular slide grinders, micro-centric grinders, chucking grinders, universal grinders, internal grinders, surface grinders, crankshaft grinders, camshaft grinders, valve grinders, thread and groove grinders, dual wheel grinders, rotary surface grinders, gear grinders; motor controlled spindles for all these dressing tools; motors for spindles for these dressing tools; machine tools, namely, single point diamond turners; diamond cutters; electrical motors, namely, servo motors and stepping motors; hydraulic, pneumatic or electric spindles for use in dressing tools; machine tools, namely, mandrel assemblies for dressing tools; direct drive shafts for rotary spindles being parts of dressing tools; and bearings being parts of spindles for use in dressing tools