Suspension control unit and control valve

A kneeling valve assembly for transport vehicles to enable a quick and convenient kneeling operation to permit safe ingress and egress from the vehicle. The kneeling valve assembly employs a suspension member positioned between the vehicle body and the axle of the transport vehicle to raise and lower the transport vehicle relative to a ground level. The kneeling valve assembly includes a first valve that is operable to selectively permit fluid flow between the inlet passage and the suspension member to raise the transport vehicle relative to the ground level. A second valve is provided that is operable to selectively permit fluid flow between the suspension member and the exhaust passage to lower the transport vehicle relative to the ground level. A leveling trigger is fluidly coupled to the inlet passage and is operable to determine a height of the transport vehicle relative to the ground level. Finally, a third valve is provided that is operable to selectively permit fluid flow between the inlet passage and the suspension member to maintain a predetermined height above the ground level.