Abstract: An encoder scale is a piston rod for use in a pneumatic or hydraulic cylinder. The method includes the steps of providing a mask defining a required groove pattern on an encoder scale member that is formed from a first material (e.g. steel) and etching material from the encoder scale member, through the mask, to form a plurality of grooves in the outer surface of the encoder scale member. A second material such as copper is then deposited on to the encoder scale member to substantially fill the grooves, the second material having a different magnetic permeability than the first material. A machining process (e.g. grinding) is then used to remove any excess second material and thereby provide an encoder scale member having a substantially smooth outer surface. A step of coating the outer surface of the encoder scale member with a metal, such as chronium, is then performed.

Abstract: A vertically-movable carriage 18 has an attached first electric motor 22 which, through rollers 24, provides a friction drive with a traction bar 16. The carriage 18 is connected by a wire rope 26 to a counterbalance weight 32. The weight (32) has an attached second electric motor 36 which, through rollers 38, provides a second friction drive with a guide bar 34. The total mass of the motor arrangement is thereby split, with one motor compensating for the other.