Trailing Arm Suspension from NECI

The advantage of the independent trailing arm air suspension “TAS” is that each wheel is suspended and sprung independently of any of the other wheels. This results in a much smoother ride in rough terrain, especially at paces faster than a walk. For the same reason this suspension increases safety because it is less likely for the driver or navigator to get “pitched” out of the carriage when hitting an unsuspected bump, ditch or similar obstacle when proceeding at a fast pace.

Another benefit of the trailing arms is that the ground clearance is improved as there are no axles under the carriage and the platform on which the navigator stands can be lowered, thereby lowering the center of gravity, which is always an issue with marathon vehicles.This type of suspension is not new. It has been used on some motor vehicles and trailers for quite some time. More recently it has been used on Marathon vehicles, usually in conjunction with torsion springs or with coil springs.

About five years ago Poj-Kon, makers of NECI carriages, started to offer “Independent trailing arm air suspension” as an option on marathons and wagonettes. The trailing arms replace the conventional steel axle (aka “live axle”) The axle stub for each wheel is welded to a small triangle shaped steel frame, which hinges on the carriage frame about 12 inches forward of the wheel hub. A bellow shaped heavy duty rubber air bag is mounted between the rear end of this triangle and the frame of the carriage and acts as a spring. This spring action is dampened by an automotive shock absorber. The air bags (or bellows) are commercial grade, and are made to German automotive specifications of heavy duty rubber. The air pressure is approximately 35 PSI and can be increased or decreased by means of a standard tire valve. Should the bag go flat for any reason the affected trailing arm will lower itself to a solid rubber stop and the carriage can be driven home, albeit without the benefit of a spring on that wheel.

There was some skepticism about this air suspension at first, but time tested experience has proven the skeptics wrong. Several NECI customers who have ordered the TAS system on multiple types of marathons and wagonettes have come to really appreciate this $ 370 option.