More Information on TRS

Why Trailer-based Rollover Systems?

Trailer-based rollover systems, like the Haldex Trailer Rollover Stability (TRS) System, have distinct advantages over tractor-based rollover stability systems.

Why does it make sense to control rollover situations at the trailer instead of the tractor? The tractor, with its relatively low center of gravity height, effectively separates the driver from the trailer due to the decreased tractor roll motion. As a result, the driver often remains unaware of the rollover instability at the trailer and fails to take corrective actions in a timely manner, or often overcompensates with erratic steering. In fact, most driver steering movement is amplified by the time it reaches the trailer. Therefore, the trailer is most likely to see the highest lateral forces. It’s not surprising that most drivers are unaware of rollover conditions until it’s too late.

 Study Points to Trailer-based Rollover Systems

A study, published by ASME and written by the University of Michigan*, concurs that trailer monitoring is important. The study found, “a driver’s awareness of rollovers on vehicles depends on vehicle type, load position and torsional stiffness of the trailer. Torsionally flexible trailers result in poor roll feedback to the driver, especially on flatbed trailers. Since the tractor has a relatively low center of gravity height, it effectively separates the driver from the trailer due to the decreased tractor roll motion. The driver often remains unaware of the rollover instability at the trailer and fails to take corrective actions in a timely fashion. However, if the trailer is monitored and an accurate and timely warning is issued regarding an impending rollover threat, it is possible to avoid some rollover incidents.”

Secondly, since trailers are typically retained longer than tractors, the trailer-based rollover system is more cost effective. It makes sense because the trailer-based system allows you to spread the initial system cost over a longer period of time. Or, if you frequently use leased tractors or contract owner-operators, the trailer-based system provides the roll stability that may not be present on the leased tractor.

The new Haldex TRS can be retrofit to current trailers in addition to specifying the Haldex TRS system on a new trailer at the OEM. The system can be installed in the field in about the same amount of time that it takes to install most ABS systems. Tractor-based rollover systems, however, are more costly and often impossible to retrofit in the field.

*Study published for Proceedings of the 1999 ASME International Congress and Exposition (November 1999) by the University of Michigan, Department of Mechanical Engineering and Applied Mechanics.