Abstract: A vibration isolation suspension system comprises a support plate mounted on a main support plate on the spaced parallel frame members of a truck tractor. The support plate is mounted on a transverse pivotal axis located near the forward end of the tractor. An air bag suspension system is mounted between the support plate and the main support plate. First and second open-ended cylindrical members are attached to each of the plates and surround the air bag in sliding relationship with one another to minimize lateral shift and roll of the fifth wheel support plate. The main plate is adjustable longitudinally on the tractor frame to adjust the fifth wheel position.

Abstract: A vibration isolation fifth wheel suspension system comprises a fifth wheel support plate mounted between the spaced parallel frame members of a truck tractor on a pivotal axis located near the forward end of the tractor. The plate is located to rest on the upper surface of the frame members and its free end is mounted on a pressurized air suspension supported by a cross member extending between the tractor frame members. Two pairs of first and second cooperating wear plates are used to minimize lateral shift and roll of the support plate. The first plate of each pair is attached to and depends downwardly from the under surface of the support plate in sliding relationship with the second plates of each pair which are fixed to the cross frame member.