Glossary › W

Retarder brakes

Retarder brakes ensure high brake performance with minimal wear. Also known as eddy current brakes. Electricity is provided by the tractor unit. When used, magnetic fields and magnets brake rotating rotors. ABS braking systems are connected to the retarder brakes and when ABS is activated the retarder is immediately turned off. On air suspended trailers the retarder brake can also be activated via the ALB. Disadvantage : excess weight. On hazardous goods vehicles an additional cooling system is required.


Expert opinion on the value of trailers and semi-trailers is available from various institutions e.g. in Germany the valuation publication from trailer tax (see

Walking floor

System for loading/unloading trailers. Full-length floor panels are lifted, shifted and lowered in order to move goods along the load deck. Often used when tipping is not possible.

Warning light

Used on special transport vehicles. Rotates and flashes in all directions.

Warsteiner axles

German axle manufacturer.

Waste collection vehicle

Large volume vehicle used for collecting special waste. The body is aluminium, open topped or with top hatches and usually fitted with a load crane and may tip.

Waste disposal containers

Waste disposal containers, which are set down and picked up via a cable system.

Waste disposal trailer

Trailers used for waste disposal equipment like skips, roll-on containers etc.

Water release valve

Valve used to release water build up in air hoses.

Water trough

Found in live animal transporters.

Weight increase

Generally this is the approved increase in the total weight capacity of a vehicle in agreement with the manufacturer.

Weight reduced

see Ablasten/weight reduction

Weight reduction

The total allowable weight of trailers and semi-trailers may be downgraded by their owner. For example if a tractor unit has a maximum towing capacity of only 12 tonnes a 16 tonne trailer can be downgraded to 12 tonnes. In Germany this requires a TÜV certificate in accordance with paragraph 19 of the German Regulations. Trailers with load sensitive brakes require no technical action. The total allowable weight is changed in the vehicle registration document.

Weld-on eyes

Housings for suspension or draw bar bolts.

Weld-on hinge eyes

Female hinge component that is welded to the side rave of vehicles with drop-sides.

Wheel chocks

Compulsory in Germany according to road traffic regulations. Prevents stationary trailers rolling away.

Wheel rims

Trailers use standard rims and offset rims (for tandem wheels).

Wheel track

The distance from centre to centre of two tyres on one axle.

Wide tyres

Used to provide a large tyre contact area e.g. 445/65 R 22.5 for construction vehicles.

Winch, electric

Usually used on off-road vehicles and low loader trailers where a cable is used to pull on loads.

Wisadeck flooring

A multi layered high strength timber flooring material for trailers and semi-trailers.