Abstract: An apparatus that prevents collapse mode and sling-shot mode of the accumulated air spring vibration isolation system is presented. The apparatus is contained in an air spring which is connected to accumulator. The apparatus blocks air flow to the accumulator when the air spring is attempting to bottom out, resulting in a soft pneumatic stop for the suspended mass. High pressure air within the air spring at its lowest height is evacuated to the accumulator, thus precluding a “sling shot” reaction of the suspended mass. The apparatus incorporates a double acting air cylinder with an orifice disk attached to a piston shaft end and an orifice contained within the air spring head. The upper air cylinder volume is vented to the air spring interior compartment through an unrestrictive orifice and the lower air cylinder volume is vented to the high pressure source through a highly restrictive orifice.