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Class 115 Derby 4-car DMUs


Description

While the vehicles appeared externally similar to Class 127 vehicles, the biggest difference being the Class 115 TCL vehicle had a slightly different window layout than the Class 127 TSL vehicle, with one full size window being replaced by two half windows where a bulkhead divided the first class area into smoking / non-smoking.

Internally they had improved seating, furnishings, lighting and wall surfaces, due to the work of the BTC Design Panel who wanted to remove the bus type atmosphere from the sets.

First Class

This is the first class.

2nd Class smoking

This first view of a second class has an unpatterned moquette (the scan has added the dots).

2nd Class non-smoking

This view of a second class non-smoking saloon shows moquette that was also used on the Class 126 Swindon units built for Ayrshire.

Over the years the sets had a variety of buffers, including cut, oval and large round. In 1981 some power cars were fitted with power sanders to aid adhesion.

Modifications

Exhausts

On the rear end of the power cars the exhausts were plain pipes rising up to join into a single box - see this image. Beginning in 1965 alterations began to be made so the pipes no longer joined. By circa June 1965 at least seven vehicles had this done: 51654/62/74, 51865/81/4/95[1]. By mid-1966 51653/4/6/8/9/60/2/7/74/5/8/9, 51862/5/6/9/70/4/5/6/81-4/6-9/95/7/9 and 51900 had been treated.[2]

In mid-1976 two power cars (one being M51857) were fitted with a new type of exhaust silencer as an experiment. It included an expansion chamber equal in volume to the swept volume of the engine, fitted as close to the exhaust manifold as possible with large-diameter pipe leading to an increased-capacity exhaust silencer. The level of exhaust noise usually associated with these units was significant reducted in initial tests[3].

Later on the exhausts had an additional sliencers added on the inner ends, as shown in the image.

Sanding Gear

David Hatt was a commuter to and from Amersham in Autumn 1978: "One evening the 17:12 from Marylebone to Aylesbury stalled on Chorleywood bank due to leaves on the rails. I was waiting on Amersham station and watched a Class 25 pass southbound to rescue the DMU. London Transport were not best pleased by this incident, since it completely disrupted the Metropolitan Line service in the evening peak. For the next several weeks, DMUs were not permitted to run over the Metropolitan Line, and so BR operated an Aylesbury to Amersham shuttle."

"The first modification to the Class 115s was the fitting of a funnel in the guard's van, with a hose down to the bogie. This allowed the guard to pour sand into the funnel, thus facilitated sanding at the wheel/rail interface. I have a feeling that it was this modification, implemented quite quickly, which convinced London transport to lift their ban on DMUs running over the Metropolitan Line. It was either the following year, 1979, or 1980 that the sandboxes started to appear on the bogies."[4]

Class 115 sanding gear

The image shows this sanding gear fitted to the front bogie of M51656. The sandbox can be seen to the right of the left hand axle with a pipe to discharge the sand under the wheel.

Gangways

Vehicles began to be gangwayed in late 1986, and initially this was to create hybrid 115 DMBS/108 DTCL sets for Network South East. The first two treated were 51654 and 51878, the work being done at Tyseley.

Vehicles transferred to Tyseley would also be gangwayed. Many of the vehicles remaining in the London area would remain ungangwayed.

Other Modifications

Here are details of some of the many other modifications made to the class, detailed in LMR Traction Bulletins:

Issue 4 - October 1972

Issue 36 - May 1983

Issue 39 - August 1984

Asbestos

The vehicles were built without blue asbestos. They were included in a vehicle log kept by the RTC at Derby dated circa 1984 which included the asbestos status for each vehicle, the pages of which are included below.

In the asbestos columns the / meant they were not built with blue asbestos, in the remarks column SV meant seperate van (no access to train).

RTC DMU vehicle log page 82

51651 - 51670

RTC DMU vehicle log page 83

51671 - 51859

RTC DMU vehicle log page 84

51860 - 51880

RTC DMU vehicle log page 85

51883 - 51900

RTC DMU vehicle log page 86

59649 - 59668

RTC DMU vehicle log page 87

59669 - 59722

RTC DMU vehicle log page 88

59723 - 59743

RTC DMU vehicle log page 89

59744 - 59763

RTC DMU vehicle log page 90

59764


References

  1. p277 August 1965 Railway Observer
  2. p268 August 1966 Railway Observer
  3. Diesel unit silencing trials, p324 August 1976 "Modern Railways" (Ian Allan)
  4. Email David Hatt to Stuart Mackay 4 February 2021

The Railway Observer is the journal of the Railway Correspondence and Travel Society