Abstract: A device for taking up wear in a disc brake assembly which is particularly suitable for aircraft comprises first and second spaced jaw members carrying a piston and cylinder actuating assembly operable by fluid pressure to displace friction linings and disc brakes towards one of the jaw members to compress the friction linings against the disc brakes and effect braking. The piston is in two telescoping parts and friction rings disposed therebetween normally retain the relative position of the two piston parts against the effect of a spring which operates on one of the piston parts to return the piston to a rest position. The displacement of this one piston part from the rest position is limited by an abutment and, in the event of this limited displacement being insufficient to effect braking, due to wear in the friction linings, the other piston part is displaced further by the fluid pressure against the effect of the friction rings to effect braking.