MV135 (3) Scania Highline 2+4 Tractor unit - N GAUGE -
Picture includes illustration of model when complete
Model comes in kit form and requires construction and painting.
Parts to build one 2+4 variant. Includes 'Suzie' cables
Background:
There are many types of ‘Tractor Units’ in use. They are designed to haul a wide range of trailers connected to the tractor unit by a fifth-wheel hitch system mounted just forward of its rear-most wheels, these units also carrying a share of the total laden weight. To carry the maximum permitted gross weight of 44,000 kg (97,000 lb) in the UK, both tractor and semi-trailer must have 3 or more axles each. Tractor units with 3 axles are fitted with 8 tyres; these are known as 6-wheelers or 2+6’s, with one of the rear axles having single wheels which normally steer as well as the front axle. On some Tractor Units and some Semi Trailers one of the axles can be raised when not needed, the tyres not touching the ground (i.e. when unloaded or only a light-weight load is being carried) This axle arrangement is known as a TAG axle. The UK also allows tractor Units which have 6 tyres on 2 axles; these are known as 4-wheelers or 2+4’s, and have maximum weight limitations dependent on the type of road-tyre fitted.
Tractor units provide the semi-trailer with air-brake and electrical services, these connected by flexible brake air-lines and multi-core power cables called "Suzies". These are mounted on the back of a Tractor Unit and get connected to the semi-trailer once hitched using a colour coded system. The red air-line is for emergency brake supply, blue air-line is for brake control and the black multi-core line is for electrics, powering road lighting. Occasionally a fourth multi-core electric power line exists, coloured green, this providing additional electrics for extra flood lighting, electric driven hydraulic pump-motors, refrigerator cooling systems, electric powered landing gear etc. etc. The electric flexible cables are also referred to as pigtails.
The models:
Our Tractor units are offered in both the 2+6 and 2+4 variants some incorporating wind-deflectors, these variants spanning the mid 1990’s through to the current day. With the cabs being spun-cast metal they become a solid weight and this has meant the chassis design needs to be heavy in order to balance the cab weight. We have achieved this by incorporating a mesh looking walk-way on the top and making the underside as solid as possible, not attempting to show drive-line and other details, a compromise which we think is acceptable as rarely would you look at the underside of the vehicle