Wire for safety

John Baxter | July 01, 2010

Melletat says that in some applications Meritor Wabco’s RSC can apply the front axle brakes. The ESC system includes a brake pressure sensor to report to the system what the driver is doing with the brakes to effectively apply appropriate pressure levels.

Both companies also supply trailer-only systems. They rely on a lateral acceleration sensor to apply trailer brakes when a rollover is imminent. The Bendix truck/tractor systems can’t be retrofit, while the Meritor Wabco truck/tractor systems can be in some situations.

Collision safety systems

Radar, often used to catch speeders, can also be employed to warn a driver whose speed and following distance indicate an imminent front-end collision. Eaton Corp. developed the Vorad Collision Warning System and later integrated it with vehicles’ cruise control systems. Bendix purchased the Vorad system and integrated it with its ESP, renaming the combination Bendix Wingman ACB (Active Cruise with Braking).

Because these systems work with other safety systems, they can prioritize the alerts.

“For example, if you have an indication of lane departure and an impending collision, you can have the system indicate an impending collision first,” Andersky says. “Audible alerts can vary in sound from one another so the driver will know what the alert means without needing to look away from the road.” An integrated system also costs less than the component systems installed separately.

When the system detects danger, it de-throttles the engine and, if necessary, employs the engine brake and even the foundation brakes to slow the rig until its speed matches the speed of the vehicle in front. This saves the driver from constantly resetting cruise speed control to follow slower vehicles. This function operates in cruise only, but a version available by year-end will work all the time.

An optional switch allows the driver to set following distances (figured as the time) from the default value, 2.8 seconds, up to 3.5 seconds. Wingman ACB has also been upgraded to provide warnings and alerts on stationary objects.

Bendix also offers the Vorad system with active cruise, a system that does not require ESP. The major cruise control-related performance difference with Vorad is that its active cruise function de-throttles the engine and uses the engine brake, but it does not activate the foundation brakes to hold the vehicle at a satisfactory following distance. Vorad alone can be retrofit, while Wingman ACB is available only on new vehicles.

Meritor Wabco offers a similar product, the OnGuard Collision Safety System. Melletat says, “OnGuard is an Adaptive Cruise Control (ACC) and Collision Warning System (CWS). ACC is a radar-based tracking system that works in conjunction with standard cruise control to maintain the set cruise speed when no vehicle is being tracked, but maintains a safe following distance when a target vehicle is being tracked.”

The safe following distance is maintained by controlling the engine throttle, the engine retarder and the foundation brakes without driver intervention, Melletat says. When the target vehicle is no longer being tracked, the set cruise speed resumes automatically.

“The CWS provides the driver with an audible and visual alert to a potentially dangerous driving situation,” he says. “It is integral with the ACC, but also functions when the cruise control is not being used. If the driver is following too close behind another vehicle at a steady driving speed, the following distance alert emits an audible tone and the in-cab dash display screen turns yellow. This alert ends when the driver’s vehicle speed drops below the lead vehicle speed and the following distance is increased.”

Melletat says that with the cruise control set, the system provides engine throttle and retarder control, as well as foundation brake activation, if necessary. This automatic brake application is intended only to provide early braking as the driver is recognizing and reacting to the situation. It is also the driver’s responsibility to apply the brakes in response to the collision warning, he points out.

The Wingman ACB system records data such as following distance and hard braking events. Andersky says, “The fear is that such data can be used against you in court. In fact, fleet managers are embracing such data. You can act on the information in deciding whether to settle or go to court. If your driver performed effectively, you can use this evidence in court. And if the evidence shows your driver was at fault, you can settle the claim instead of fighting it through litigation.” n

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