caliper to allow bleeding of the braking system. Whenever service work has been performed on the braking system which might have introduced air into the system (i.e. the hydraulic system has been opened), the air must be bled out. This is necessary for correct operation of the system, because air compresses (as opposed to brake fluid which is not compressible). Air in the system reduces the maximum pressure applied to the brake pistons and can lead to loss of braking ability. Hydraulic operated clutches Cars with manual gearshift use a clutch. Clutches are controlled from pedal by bowden cable or hydraulic systems, some use the fluid in common with the brake system. As a dead end of the hydraulic system, the slave cylinder is equipped with a bleed screw. See also Automatic bleeding valve Radiator (heating) Degasification References Residential heating Hydraulics Heating, ventilation, and air conditioning Plumbing valves