An actuation system includes a magnetostrictive pump assembly (12) to operate a fluid ram (14) such as a brake cylinder connected to an actuator such as a brake (pad 20). A first accumulator (30) is connected to an input of the fluid ram (14) to store a fluid which actuates the fluid ram (14). A second accumulator (34) is similarly connected to an output of the fluid ram (14) to receive the used fluid after actuation of the fluid ram (14). The magnetostrictive pump assembly (12) is connected between the first accumulator (30) and second accumulator (34), to transfer the fluid from the second accumulator (34) to the first accumulator (30) such that the fluid is maintained at a high pressure for activation of the fluid ram (14). As the magnetostrictive pump assembly (12) reacts essentially instantaneously, any delay between actuation or deactivation is practically eliminated. Further, although the displacement of the pump (12) is relatively small, it can be cycled at extremely high frequencies to provide substantial pumping capacity for immediate brake activation.