First look: Bosch Trailer Safety System

New hi-tech safety system set to revolutionise the anti-sway trailer market

Towing a large trailer behind your car or ute can be a tricky thing, with many factors affecting the vehicle dynamics. While many trailers are fitted with electric braking systems, changes in weight, load distribution and weather conditions can dramatically alter their effectiveness.

In recent times, some car manufacturers have introduced Trailer Sway Mitigation as an added feature on their vehicle stability control systems, but this is by no means a guaranteed method of maintaining control in all conditions.

Even in perfect conditions, Trailer Sway Control may not be up to the task of keeping things in a straight line, with the trailer and load often being heavier than the tow vehicle. This presents a problem when you rely on a two tonne car to maintain control over a three tonne trailer, with the heavier of the two usually winning when things go wrong.

While the tow vehicle might have all the latest stability control and ABS technology, this doesn’t have any effect on the trailer and often leads to the tail wagging the dog, so to speak. This is where the Bosch Trailer Safety System can help, which takes existing systems from AL-KO and Dexter up a notch…

Slow and steady

While caravanners are known for being slow and steady, the Bosch Trailer Safety System takes that to a whole new level. The system uses technology derived from Bosch’s long term development of vehicle stability control systems, and puts it into a package that can be fitted to any trailer with up to three axles.

The system provides all the benefits we have come to associate with Anti-lock Braking Systems (ABS) and Electronic Stability Control (ESC), and not only reduces stopping distances but also works to keep the trailer upright and in line with the tow vehicle.

As Gavin Smith, President of Bosch Australia explained, the concept came about after he did a trip from Melbourne to Sydney up the Hume Freeway.

“When you see three cars and caravans on their roof between Melbourne and Sydney it sort of makes you think there’s a problem here, and surely there must be a solution” he said.

“But I was also aware that we already have trailer sway mitigation algorithms in stability control systems in most modern cars anyway. So, if it’s already fitted, why do we see these safety issues where caravans go upside down? The first thing is that not all cars have it and, secondly, it’s acting on the vehicle, not on the trailer being towed.

“You can’t change the laws of physics; if the caravan’s on its way, the car can’t fix it,” he said. “We then came up with an idea to apply stability control and ABS onto the trailer. Development started close to two and a half years ago, and here we are today showcasing something that we hope will find its way onto every caravan and heavy trailer that is produced.”

How it works

Bosch’s Trailer Safety Control System incorporates a few separate components, all working in conjunction with the trailer control module. As with any ABS systems, wheel speed sensors are used to measure the speed of each individual wheel, while a yaw sensor built into the control unit watches out for any trailer sway or extreme manoeuvres that might lead to a dangerous situation.

This information is monitored up to 30 times per second, with the control unit interpreting the data to detect any hazardous situations as they arise.

Along with preventing brake lock-up under harsh braking, the system can apply the brakes to each individual wheel to control trailer sway and maintain stability during harsh manoeuvres.

Both of these attributes were demonstrated at a recent launch event, with the system fitted to a Jayco caravan towed behind a Ford Ranger ute.

The benefits of the ABS were demonstrated on the skid pan, both with and without the system activated. The demonstration included an evasive manoeuvre involving swerving into the next lane while coming to an emergency stop.

In the first case, without the ABS activated, only the anti-jack knife straps prevented the caravan from destroying the back of the Ranger. With the ABS in action though, even with the severe swerving, the entire unit pulled up straight and in a much shorter distance.

The benefits of the stability control component were highlighted with repeated hazard avoidance manoeuvres, which were carried out at 100km/h. Even under these harsh conditions -- swerving right then back to the left at 100km/h -- the car and caravan both remained firmly planted on the ground.

In this scenario, the system applied braking to individual wheels to keep the van from rolling over. Even on a high centre of gravity van, as was used in the demonstration, the system eliminated the risk of rollover and kept the van tracking in line with the car, where it should be.

While it wasn’t shown on the day, Bosch is adamant that the system works just as well on any surface, including gravel and corrugations.

Made for Australian conditions
Bosch Australia are proud of the fact that this system has been designed and tested right here in Australia. What’s more, when it goes into production later this year, it will be manufactured here as well. This should give users some confidence that it will handle local conditions, and work as it should, day in, day out.

With the unit being waterproof and dust proof, this should cover units fitted to boat trailers as well as off-road caravans.

If some component of the system is damaged -- a wheel speed sensor for example – Bosch says the system will continue to work, but only on those axles not affected.

In the case of a damaged front left sensor, the front right wheel will be made redundant to prevent the trailer pulling to that side under braking. The rear axle (or axles) with still operate with full functionality, and the driver will be notified of the issue via a small LED light display fitted to the front of the trailer, visible in the rear view mirror.

Cheap insurance

Given that this technology has been around on cars and trucks for many years, Bosch have been able to borrow components from other designs. This is good news for the buyer, with a huge reduction in production cost over “all new” casing and components.

While Bosch wouldn’t give an exact price, there was a clear impression that it would come in under or around the $2000 mark. The final price will obviously depend on the number of axles, but at that price it still makes for cheap insurance against an upside down trailer.

Who knows, maybe the insurance companies will reduce premiums for those trailers with the system fitted...

First look: Bosch Trailer Safety System

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