A valve arrangement for placing a supply of motive fluid in alternating
communication with first and second motive fluid chambers. The valve
arrangement includes a power valve including a supply chamber, a pilot
chamber, and a shiftable member separating the supply chamber from the
pilot chamber. The valve arrangement also includes a pilot valve actuable
between an on condition in which the pilot valve generates a pilot signal
that shifts the power valve, and an off condition in which the pilot
valve does not generate the pilot signal. At least a portion of the pilot
valve is exposed to motive fluid, and the portion of the pilot valve
exposed to motive fluid includes surface areas giving rise to a net zero
actuating force arising from pressure of the motive fluid. Because there
is no biasing force on the pilot valve, the pilot valve is shifted
between the on and off conditions without significant resistance.