On a Roll: Truck Roll Stability Systems
On a Roll: Truck Roll Stability Systems
Many of us only think about vehicle stability after we’ve had in incident that makes it relevant. Whether it’s an evasive maneuver, poor weather conditions, or anything else, at that moment the need for vehicle stability becomes all too apparent.
With regard to commercial vehicles, which are typically heavily loaded and have high centers of gravity, the possibility of a rollover is a serious concern. There are several ways to minimize the risk, including a Roll Stability Program (Bendix RSP) or Roll Stability Control (Meritor Wabco RSC), which can complement the safety measures of anti-lock brake and directional stability control systems.
The system functions by controlling vehicle speed so lateral acceleration does not exceed a specific rollover threshold. This is accomplished by gradually slowing the vehicle by means of engine throttle reduction, application of wheel brakes and activation of a retarder or engine brake. Roll Control is derived from anti-lock and stability control systems — designed to exceed the capabilities and consistency of any driver without the system.
But the system does have weaknesses. One key limitation is that the vehicle may simply be going too fast or traction levels may just be too low to stay within the rollover threshold. Also, anything that causes weight to shift unpredictably in the vehicle, such as an improperly secured load or uneven road surfaces, can make the system less effective.
When considering the feasibility of having a roll stability system, note the vehicle does not typically require extra equipment apart from ABS and stability control. Some systems have different control units with the additional required programming and/or sensors built in. This means that a control unit may need to be changed to gain the roll stability function. These systems are also tested for specific vehicle applications and cannot be used effectively on any other models.
According to the NHTSA, the benefits of having Roll Stability Control (implied that the vehicle has ABS and stability control) include a millions of dollars in savings due to accident prevention over the life of the vehicle. This is significant by itself, but when multiplied by the number of trucks in a fleet, the benefits become even more significant.
Roll stability information can be found in Mitchell 1’s TruckSeries repair information software for Class 4-8 trucks.
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