A Scammell Mechanical Horse

A Close up of the Latch mechanism on a Mechanical horse tractor
The Scammell coupling was used on wheeled Horse Tractors and Scammell units. It was early type of Fifth wheel coupling, designed to allow easy swapping of trailers. The early users were the railway companies for local distribution vehicles.
The coupling was in two versions;
- 3 ton
- 6 ton - latter used on the Bedford trucks[1]
Operation[]

A Scammell coupling 6 ton showing the Jockey wheels stowed and the guide ramps, with the turntable located above the tractor units rear axle.

A Scammell coupling 6 ton on a Bedford. The latch mechanism and the turntable can be seen with the flange of the guide roller visible to the right of the mud guard

A restored Bedford Scammell tractor unit and stepframe trailer
A Step frame trailer showing coupling in the trailer detached position with landing wheels down.
The coupling has two ramps attached to the rear of the tractor unit's chassis and coupling hooks situated in front of the rear wheels. The trailer frame had a wheeled 'undercarriage' mounted below the turntable with a drop down Jockey wheel unit for when parked. The turntable unit had two rollers that run up the tractor unit ramps. The Jockey wheel frame unit automatically folded back as the rollers ran up between the tractor ramps after striking the release plate situated below the ramps, which released the spring loaded latch.
The tractor units securing hooks then engaged with the lugs on the trailer, attaching it securely to the tractor unit. The trailer brake and trailer light connections were made automatically and all the driver had to do was fix the registration plate to the rear of the trailer and release the hand brake on the trailer.
See also[]
- Hitch - description of various hitch types
- Fifth wheel coupling - Modern turntable and pin hitch system.
- Scammell - Main page
- Mechanical Horse Club - Owners group
- Mechanical Horse - First version
- Scammell Scarab - Later version
- Scammell Townsman - Modern version
- Reliant Ant - Revival version
- Bedford Scammell (Bedford OSS) a 4 wheeled trunk version