Sign In

  Remember Me

Not registered?

Class 120 Swindon 3-car DMUs


They had much in common with the Class 126s, although the passenger accommodation was revised for their different duties. The underframe, floor, bodysides and roof all formed an integral construction, with stress-bearing steel panels. The underframe was lighter than the 126's, and they had screw couplings instead of buckeyes (the only Swindon cars to do so). The floor was formed of 14 s.w.g. corrugated steel sheet welded to the underframe sections, and the body and roof panels were of 16 s.w.g. sheet. The interior side of all panels and roof plates were sprayed with asbestos, and the corrugated floor was packed with asbestos and covered with insulating board.

Rear End

The guards vans were at the rear of the vehicles, unlike the 79xxx Inter-City sets which had received much critisism over the passengers lack of forward/rear view. The image shows the details on the rear end of 51782 while at Ayr depot. When new there were addition footsteps (where the clusters of bolt heads are) and no silencer on the exhaust, the exhaust would have been covered in grille to prevent staff touching the exhaust while climbing the footsteps. Bill Hamilton.

The standard BUT power train and control equipment was used, with 150hp AEC engines and S.C.G. Wilson epicyclic gearboxes. This gave about 5 3/4 bhp per ton of tare and about 5 bhp per ton fully laden. They had a maximum speed of 68mph. Over the years Leyland engines were fitted, the first being to 50674.

As on most DMU sets, the handbrake was operated by a wheel in the cab, and Graviner automatic fire protection equipment was fitted. This was mounted over each engine and discharged chlorobromethane onto the engine if it became seriously overheated. The engines were also protected by a low water shut-down switch, which shut of the fuel to the engine if the water in the header tank fell below a certain level. An oil pressure switch also shut down the engine if the pressure became too low. The operation of these devices was immediately brought to the attention of the driver by warning devices in the cab.

Cab Controls

The drivers controls in the cab of a Class 120 set. Almost identical to the 1959 Class 126 sets, the difference being the switch panel between the throttle / gear controllers. Michael Kaye 55A.

Most sets were built with 4 headlights, but the final batch had a four character route indicator, and only 1 lamp, to the left of the headcode. They latterly had the headcode box removed and a second headlamp added.

Four Character

This image shows a set with the 4-character route indicator. It's set B555 at Maiden Newton, 51590 leading. April 1975. Robert Frise Collection.

Some of the Cardiff based sets were later equipped with headlights for use on the Central Wales line.

Sets had a mixture of oval and round buffers. Grilles covers were fitted around the exhaust where it rose either side of the gangway. 59301 had B4 bogies fitted at some point.

When delivered, they were described as being able to be re-marshalled into 5, 7 or 8-car sets, which may account for the different number of trailers built.


Publicity Photo

Interior side and cross panelling, and ceilings in all cars were of pastel-patterned Formica in different shades. The side walls of the first class in the DMBCs had a birds-eye maple design which was also used for the lower portions of the vestibule partitions. The partitions contained large observation windows. The ceilings were an off-white colour. In second class saloons a light green wood-grain plastic was used for the side walls and ceiling and contrasting wood-grain pattern for the end partitions. The walls in all lavatories were finished in mottled grey and white plastic, with sage grey plastic floor tiles.

The first images shows a 2nd class saloon full of 'models', a posed image for publicity purposes. They are probably Swindon Works staff as they are recognisable from similar WR publicity images. The second image shows an empty 2nd class saloon.

Publicity Photo

Metal fittings were generally finished in natural anodised aluminium. Lighting was by circular fittings in the ceiling, supplemented by small tubular lights over each set of seats, incorporated in the aluminium luggage racks which ran the complete length of both sides of the saloons. Curtains were fitted throughout, and carpets in 1st class. Oval mirrors were fitted to saloon ends.

Heating was by two oil burning Smiths-Webasto combustion heaters. Warm air was carried in ducts underneath the floor to outlets beneath the seats. The air intake from these heaters could be drawn from outside, passing through an Ozonair filter, or in cold weather a portion of the used air could be recirculated with the selection being under passenger control. There was also thermostatic control of the temperature.

Seats were the tubular frame type, with high backs, hair and spring filling in first and Dunlopillo cushions and backs in the second class. Second class upholstery was in shades of green, with cream leatherette headrests. First class was upholstered in moquette of grey & gold pattern on a black background.


Small collapsible tables were fitted against the side walls at each pair of seats, so that refreshments could be served from the small buffet counter kitchen. This had a small hot-water boiler burning propane stored on the underframe and an electric refrigerator, store cupboard, sink, display cases and shelves. The shelves were finished with a light coloured plastic. The front of the counter was in the form of hinged flaps which could be raised and locked when closed. Plastic panelling above and at the sides of the buffet counter was in a medium Australian walnut design. An electric extractor fan was fitted in the ceiling. Opposite the buffet were four wall seats.

Hot water for the toilets was provided by electric heaters.

In the mid-'70s the curtains were removed due to costs, and in 1983 all the 1st class saloons were declassified to 2nd. The buffets saw limited use, and before long they were regarded as trailer seconds. By the mid '70s the facilities were made redundant, but left in situ.

Western Region

Ordered in May 56, the first batch were all delivered with WR ATC apparatus. Made up of a DMS, TLSRB and DMBC, they had 18 1st and 144 2nd class seats, and 130 sq ft of luggage and parcels space. The total empty weight of approx. 103 1/2 tons represented 1,400 lb per seat. There were 49 of each power car and 47 trailers in this batch.

The third batch, 9 of each power car and 10 trailers, did not have the buffet section.

Scottish Region

The guards van door had tablet apparatus fitted. The ScR modified four of their DMBC cars (51783-6) during refurbishment by removing the two second class seating bays and fitting a pair of double doors in place of the second window each side in this area to increase the luggage space. A side corridor was installed running on the right hand side and the remaining window on the left hand side was blanked off. They were reclassified as DMBFs.


In the late '70s the Inverness sets were "refurbished". Very few WR sets were treated.

ScR set 300 (51783 / 59683 / 51792) was the first done in June '77.

The first two sets to be done were completely stripped of blue asbestos, reupholstered with bright blue check material in 2nd class and a beige-brown in 1st. The ceilings were changed from being high curved to a lowered flat finish, and fluorescent lighting. New types of heaters were fitted, which did not get as uncomfortably hot as the originals. Bold orange and blue Formica was fitted.

Unfortunately removing blue asbestos proved too costly, and only a few other cars received just superficial improvements. This also gave a sign that their days were numbered.

Vehicle 50647 had two unique features - it had two rows of very shallow fluorescent lights, and it had Leyland engines fitted.

Shortly after this, another set was noted with the two rows of small square section fluorescent lights. 53692 / 59301 / 53708 was also noted as being outstanding with cream panelling, orange vestibules and brown seats in the former first class area. The trailer had B4 bogies fitted.

© 1998 - 2018