Van, Truck, Trailer, Bus and Coach Aftermarket News in Ireland

Safety first in truck and trailer coupling and uncoupling

Two years of work by a Health and Safety Executive (HSE) working group involving SMMT, other trade associations, trade unions, traffic commissioners and the Driver and Vehicle Standards Agency (DVSA), is about to result in publication of new guidance on safe trailer coupling and uncoupling procedures.


The new, free HSE guidance will replace a similar publication dating back to 2006 and will focus more on driver training, including a pictorial guide to the safest trailer coupling and uncoupling procedures.

One of several new recommendations is that there should be a standard position on semi-trailers for the park-brake valve, making it easier for drivers to locate. It is recommended that the valve should be mounted on the nearside front of the chassis side-member, forward of the trailer landing legs.

A persistently high number of accidents and incidents involving truck and trailer runaways has prompted the HSE working group’s action. Andy Mair, Head of Engineering at the Freight Transport Association (FTA), has been part of the working group from the start and is in no doubt that fresh guidance is sorely needed.

Mair said, “This subject remains a very high priority for FTA members, including some big fleets. It is also one of the HSE’s top three priorities.”

Mair also maintained that many drivers simply do not understand how trailer parking brakes work. This has been underlined by research conducted recently by the Health and Safety Laboratory (HSL), a Buxton, Derbyshire-based HSE agency focused on understanding and reducing health and safety risks. One central conclusion of the HSL research is that failure to apply the tractive unit and/or trailer parking brakes is the primary cause of runaway incidents.
Many of the drivers surveyed by HSL mistakenly believe that there is no need to apply a trailer parking brake after the red (emergency) airline between unit and semi-trailer has been disconnected.

Mair said, “We explain in the new guidance that disconnecting the red line does not apply the trailer parking brake. This is done by powerful springs in the trailer brake actuators. If a driver parks a trailer using the red airline only then it is parked illegally, because it is parked on stored air.”

Truck operators and drivers are often reluctant to talk publicly about incidents and accidents involving dropped or miscoupled semi-trailers. However, the HSE revealed 10 years ago that it had investigated 24 fatal and serious accidents involving drivers engaged in trailer coupling or uncoupling between 1986 and 1996. Separate research by Georg Fischer, a big supplier of fifth-wheel couplings and other trailer equipment at the time, concluded that in 2005 there had been at least 2,000 “separation incidents” involving tractive units and semi-trailers in the UK, either in transport yards or on public roads.

Nobody has suggested, however, that the frequency of tractor/trailer miscouples could be blamed mainly on shoddy maintenance, or on inadequate design or construction of couplings.

Tim Moody, Fischer Automotive UK and Ireland Sales Director, said, “Every fifth-wheel manufacturer gets called out from time to time to an incident where a trailer has fallen off a tractor. Somebody will try to blame a fault on the coupling, but it is almost impossible for the coupling to be at fault. I’ve seen trucks that have covered a couple of hundred miles pulling trailers that are not safely coupled, with the king-pin just resting on top of the fifth-wheel’s jaws. You’d be amazed at how far a truck can travel in this horribly unsafe condition.”

The FTA’s Mair has worked in commercial vehicle engineering for around 30 years. “Truck and trailer runaways and miscouplings are as much of an issue today as they were 30 years ago,” he said.

Braking system manufacturers such as Haldex and Knorr-Bremse came in for some criticism 10 years ago for failing to make their trailer park/shunt valves more foolproof, with less confusing operating instructions.

Both have taken those criticisms to heart. Haldex won a pan-European Trailer Innovation award in 2010 for its Trailer Control Module (TrCM+) Safe Parking system. More recently, Haldex has introduced a newer version called the Safe Parking Single system. This model has just one, instead of two, control knobs and there is a new ‘Deadman’ feature which Haldex claims “ensures especially low-risk trailer handling during manoeuvring.” When flexible couplings between tractor and trailer are disconnected in the wrong order, the Safe Parking Single system activates the park-brake automatically.