Abstract: A fluid control circuit (10) for operation of a brake comprises a first circuit part (11) including an actuator (12) having a chamber (13) and an operating part (14), the operating part (14) being movable to release or apply the brake when fluid under an operating pressure is fed to the chamber (13), an arrangement (17) to expel fluid from the chamber (13) when the operating pressure is released, thus to apply or release the brake, a second circuit part (18), a control valve (20) operable in a first condition to permit fluid to pass under the operating pressure to the chamber (13) of the actuator (12) in the first circuit (11) part and when in a second condition to permit fluid to pass from the first circuit part (11) into the second circuit part (18), the second circuit part (18) further comprising a buffer (23) to which fluid pressure is communicated from the first circuit part (11) when the control valve (20) is moved to its second condition, and a proportional fluid valve (30) to control the flow of fluid