on the first surface 264 of the first piston portion the piston stem 290 is urged downwardly and inlet exhaust valve 310 is moved off the inlet seat and supply pressure at port 304 is then communicated to delivery ports 306 in this position the air bags are inflated to the pressure level allowed by the leveling valve this position is representative of the operation of the rear air bag suspension at higher speeds and when the vehicle operator has no desire to shift the load on the axles to improve maneuvering at low speeds fig4 is representative of the valve operation when the vehicle operator has a need to shift the load on the axles at low speeds and once the conditions are met as described above in connection with fig1 and the energizing of the solenoid valve 140 in fig4 a pressure signal or control signal from the solenoid valve is communicated to port 320 this control signal pressure operates on the second face 276 of the second piston portion and likewise the delivery pressure acts in the same direction on face 286 of the second piston portion this results in a combined force reacting against the force of spring 302 and the reservoir pressure on the upper face of the first piston portion the control pressure and delivery pressure moves the piston assembly upward which then allows the valve 310 to re seat against inlet seat 314 comparing the open position of the valve 310 in fig3 with the.