Abstract: A dual circuit foot valve for a compressed air braking system has a plunger (38) which acts through a spring (39) on a first piston (6) which carries an exhaust seat for a first double valve controlling the supply of pressure from an input port (27) to a first circuit delivery port (28), the delivered pressure at (28) acting beneath the piston (6) in a sense to cause lapping of the valve and also acting above a second piston (16) which similarly acts as a control piston for a further double valve controlling the supply of pressure from an input port (29) to a second circuit delivery port (30), a further spring 43 being carried within the piston 6 to be engageable with a projection (55) of the second piston (16) following operation of the plunger to act on the second piston to beneficially influence the differential between the two delivered pressures.