Scarab trailer

A Scammell Mechanical Horse

Scammell coupling latch mechanism detail IMG 6180small

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]


Scammell coupling (rear) IMG 6190small

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

Scammel couping (front) IMG 6189small

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

Bedford Scammell and stepframe trailer at Donnington 09 - IMG 6187small

A restored Bedford Scammell tractor unit and stepframe trailer

Scammell trailer hitch - VV shildon - IMG 0973

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 alsoEdit

References / sourcesEdit

  1. Mechanical horse club

External linksEdit

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