Backlash can be a major concern in some systems where precise movement or holding is required, i.e. in robotic, military or medical applications. Unlike many transmission products where splines or square/hexagonal drive forms are used in the product, the flange mounted clutch (type 51), power-on brake (type 52), permanent magnet brake (type 62) may be considered as `torsionally rigid`, essentially almost backlash-free.
These backlash-free electromagnetic clutches and brakes utilise a rotating drive hub & armature plate assembly where the physical connection between the hub and plate is via diaphragm spring and all parts are rigidly riveted/bolted together. The connection between these rotating elements and the shaft(s) are often with parallel bores incorporating side fitting keys or taper-lock bushes. This means each element is rigidly restrained minimising movement under load. These backlash-free products are employed in many challenging applications throughout the world.