Glossary › O

Offset: Wheel rims may have an internal section (with the bolt/nut holes) which is offset to fit around the brake drum. Mostly used for twin wheel trailers.
OMEGA floor: Laminated wooden floorboards laid between galvanised OMEGA (top hat) rails. Extremely strong construction.
One man operation: Term used to describe a technical component that can be operated by one person e.g. the operation of low loader ramps via hydraulic or spring aided means.
One-piece ramps: These are ramps on low loaders that are one piece i.e. not foldable or telescopic. Operated with the help of springs or hydraulics.
Operating hour: Operating control unit in order the count the operating hours and to inform about service intervals.
Operational pressure: In this case referring to silo and tank vehicles – usually 2 bar.
Outer skin: The outer layer of vehicle bodywork.
Over length: Term used for road trains over 18.75m long. May be required for loads which cannot be made shorter and require special approval in accordance with national road regulations.
Over-running brake: Braking system for trailers. When the towing vehicle breaks the momentum of the trailer is used to apply the trailer brakes via a system of brake rods. Approved for use on trailers with gross weight up to 8 tonnes at maximum speed of 25 km/h or at maximum speed of 40 km/h if brakes are applied to all wheels and approved on trailers without speed limit on trailers up to 3.5 tonnes when all wheels are braked. Only one trailer can be towed in this manner. Two trailers may be towed if the vehicle so built that it cannot exceed 25 km/h and the vehicles have appropriate markings.