Abstract: The present invention provides an auxiliary suspension system for a motor vehicle, in particular for a trailer truck, which serves to both supplement and protect the trailer springs and also to prevent the trailer from dropping directly onto the tires of the vehicle in the event that a spring breaks. A thick rubber mat is mounted to a plate on the bottom of the subframe of the trailer. The spring is positioned above U-bolts on the subframe which hold the vehicle springs. When the trailer is unloaded, the rubber mat extending from the bottom of the trailer subframe will normally be spaced several inches above the top of the U-bolt. When the vehicle is carrying a full load, the rubber mat will normally be supported on top of the U-bolt. In the event that the trailer springs break during operation of the vehicle, the rubber mat will support the trailer subframe on top of the U-bolt and prevent the subframe from dropping directly onto the tires.