1,067,209. Fluid-pressure brakes; internal shoe drum brakes. ROCKWELL-STANDARD CORPORATION. Nov. 9, 1965 [June 28, 1965], No. 47416/65. Headings F2E and F2F. An internal shoe drum brake, adapted to provide a master cylinder operated by the torque reaction for feeding hydraulic fluid to other drum brakes, comprises a wheel cylinder 40 which acts on the webs 17, 19 of servoconnected shoes 16, 18 and is supplied with hydraulic fluid from a pedal-operated master cylinder, and a master cylinder 42 containing pistons 50, 52 which are engaged with reinforced end portions 82, 84 of the webs 17, 19, these end portions being formed with a shallow V-groove and engaging convex bases of grooves 66 in piston ends 62, 64, whereby as the linings 20, 22 become compressed in heavy braking, and when they become worn, the force between the end portions 82, 84 and the pistons act progressively more through the inner of the two points of contact between the end portions and the piston ends, such that self-wedging action of the shoes within the drum under heavy braking is avoided. The convex ends of the pistons are formed on a radius having its centre at the centre of the cylinder 42, and the included angle between the sides of the V- grooves is from 164 to 168 degrees.