What kit do you need for trailer servicing?
Today’s trailer is a complex vehicle in its own right and therefore needs some hi-tech kit to keep it serviced properly, says Bowmonk’s Chris Bailey.
The format of the HGV commercial trailer has changed over the years from nothing more than a chassis connected to a set of axles through a steel-sprung suspension system, with the service schedule involving little more than a simple visual check of the tyres, lights and brake lining wear and chassis components.
Those were the days when a trailer’s parking brake was activated by a fully charged air system, fed from an air tank on the trailer, which worked well until the air pressure decreased through leaking air tanks, in so doing gradually releasing the parking brake. This method was soon reversed, with the brakes being applied by an internal spring mechanism, pushing the brake linings against the brake drum/disc.
Safety first
Now, only a constantly charged air feed working against the spring pressure will allow the parking brakes to be released. A significant safety improvement. This is one of many safety features fitted to today’s trailers; for a modern trailer now incorporates a host of advanced safety features to ensure a safer driving experience.
These include EBS (electronic braking system) providing a faster response to the trailer brakes when activated by the foot brake pedal, ABS (anti-lock braking system) an application to avoid a full wheel lock-up under hard braking, full air suspension affording increased stability with the airbag pressure being governed by levelling sensors which are connected to the trailer’s ECU (electronic control unit).
Other important components are the load sensing valves which govern the amount of pressure to the trailer brakes, depending on the payload weight on the trailer. Too much air to the trailer brakes and the wheels will lock up. More importantly, too little and there is a risk the trailer will ‘jack-knife’ because the tractor unit is braking harder than the trailer. So, with all of this hardware now installed, controlling all of these components, the modern trailer has in effect become a vehicle in its own right and as such commands a considerably higher level of servicing, performed by trained and qualified trailer technicians. No longer can we perform a service inspection of the trailer armed with a set of spanners and an intuitively diagnostic brain.
Check out the diagnosis
In support of this, we now use technology, in the form of comprehensive diagnostic tools like the TrailerCheck , for checking all of the trailer’s electrical circuits from the side lights to CAN activity; TrailerCheck ‘Plus’, same as TrailerCheck but with the added function of checking the status of suspension and braking airline; and SensorCheck, a small hand-held ABS sensor for checking the condition and operation of the ABS sensor and exciter ring without having to remove the road wheel.
