Co Acting Signals.

no when you put air into a vacuum system that is when the emergency brakes would operate the complete oposite to how the system works now as in when the tripcock is operated all the air is escaped to atmosphere

Co-Acting Signals.

Thank you, aetearlscourt, for clarifying that uncertainty. :-)

There were also Hornsey and Stratford-based BTH Type 1s, later Class 15 that were used on the Northern freights and I think the Central. Also there were the ex-SR locos ...condensing?...that served the south London freight depots that ran off the ex-GER via Liverpool Street, Shoreditch, and New Cross/NX Gate.

The photo published on this forum of 2 x J15s on an excursion begs the question as to whether they had tripcocks? Well, I should have known better! I learned to drive on the North Norfolk Railway, and of course they have the surviving J15. This is the info about it:

65462 was allocated to Norwich Thorpe in June 1960 and then moved to Stratford in January 1961, still carrying its 32C shed plate! Later in the year it had air-brake trip-cock equipment fitted on the right-hand loco rail-iron and under the left hand tender frames for use on the Leyton to Epping/Ongar line.The former GER branch was by then part of London Transport's Central Line, but BR J15s hauled occasional specials and freight trains on it until April 1962.

The last four were withdrawn September 1962.

There is no evidence yet that the ACV railcars were fitted with tripcocks but someone may know?
www.railcar.co.uk/hisOthers/ACVops.htm
I have seen a photo of the three-car set at Epping.

Perhaps this should go in the historical topics but I wrote this about 20 years ago as part of a book which was never published:

As early as August 1935, the LPTB is recorded as having doubts about the costs of electrifying the outlying branches of the newly-expanded system. The section of line from Loughton to Ongar was first mentioned in an instruction dated 12th August 1935 which advised that “the Board’s policy would be not to electrify the line” and that the newly-appointed Chief Mechanical Engineer, W.S. Graff-Baker, was to make enquiries as to suitable rolling stock. No particular form of motive power was mentioned as “suitable” but, within a week, one of Graff-Baker’s “people” (as he called his staff), E.T. Brook, Superintendent of Rolling Stock, had been to Gloucester to see a diesel railcar under construction. The time of his visit suggests that this was probably No. 6 of an order being built for the Great Western Railway.

The GWR had become interested in diesel railcars in the early 1930s and took delivery, in December 1933, of the first of a total of 38 which they were to acquire. This machine was designed as a single car of the diesel-mechanical type. It was built by the Associated Equipment Co. of Southall (AEC) with streamlined bodywork by Park Royal Coachworks.

More diesel cars were ordered by the Great Western, those from No. 5 onwards having their bodies built at Gloucester. Brook went to Gloucester to see them under construction but he was not convinced that they would be suitable for the Underground. When he came back to London he told Graff-Baker so. Graff-Baker went to the Board with these doubts. They were based on the fact that the costs of operating a small fleet of non-standard vehicles would be expensive. He used figures to prove that the savings arising from using diesels would be marginal compared with electrification.

Brook was well aware of maintenance problems, as he had been in charge of the Underground’s operating fleet since just after the First World War and was he originally based at Ealing Common, which was the Underground’s largest overhaul works before Acton was opened in 1922. Brook gained a reputation there for being a kindly man and was nicknamed “Uncle Brook”.

What is interesting about his 1935 report to Graff-Baker is that it assumed that full electrification to Ongar would be necessary within five years. The housing development which had taken place wherever new Underground services had been introduced over the previous twenty years was expected to continue. It was assumed that this would be the case in the Epping area. There was no suggestion at that time of a ‘‘green belt’’ restricting housing growth.

Graff-Baker proposed to continue electrification beyond Loughton to Epping “at least” and to use “rail motors” only on the Epping-Ongar single-track branch until development required electrification. This idea was further developed by the Operating Manager, J.P Thomas, into electrification all the way to Ongar, using a 2-car unit (DM-DM) of new tube stock (1938 Tube Stock) but with only one motor car under power. The motors of the other would be isolated to keep the current consumption down and thus reduce the substation requirements. The proposed service was to be a shuttle every ten minutes between Loughton and Epping, with every other train extended to Ongar. When housing development required more trains to Ongar, the idea went, the line between Epping and Ongar would be doubled and the traction supply system improved to cope with the extra trains.

With the Board’s approval of this scheme, which was eventually given in September 1936, the idea of diesels to Ongar was shelved for the time being. The original 1938 Tube Stock order was placed with the 2-car shuttles in mind. However, the Second World War delayed the extensions and electrification at the eastern end of the Central Line until the late 1940s when the whole subject was raised again, as we shall see.

In the meantime, in spite of the CME’s doubts, the use of diesel railcars was still being considered by the Board. Obviously pushed by the manufacturers after the visit by Brook, the LPTB continued investigations into the AEC railcars but now as possible vehicles for use between Rickmansworth, Amersham and Chesham, as a cheaper alternative to electrification.

Electrification to Rickmansworth, Amersham and Chesham was part of the 1935-40 New Works Programme but, like the eastern extremities of the Central Line, traffic was fairly light and there were again doubts about the economics. Diesels were again proposed as an alternative.

In their sales drive, AEC wanted to give the LPTB a close look at one of their machines in action, so they arranged for a demonstration of a new railcar prior to its delivery to the GWR. The demonstration was to be over the section between Aylesbury, Chalfont & Latimer and Chesham. It was arranged to occur on 20th March 1936 using GWR car No. 16. A party of senior officials from the LPTB and the LNER travelled to Aylesbury to meet the test train. From there, they were taken (at quite a lively speed by the accounts of the trip) to Chalfont & Latimer where the car reversed and then went to Chesham .

Railcar No. 16 was one of the series constructed by AEC with bodywork by Gloucester. It was one of the first batch, with a streamlined body and without conventional buffers. This distinguished it from later models, which had conventional buffing gear and a more angular version of the body. The early versions were fitted with two 120 b.h.p. diesel engines and a mechanical drive transmitted through gears mounted on the axle ends. The chassis and engines were built by the Hardy Motors division of AEC.

No. 16’s body was wooden-framed and steel-panelled in a streamlined shape, and included a fairing which covered the underfloor equipment. Because of their appearance and the GWR brown & cream livery, these railcars were sometimes irreverently referred to as “flying bananas”. Vacuum brakes were fitted, driver’s cabs were provided at both ends and a top speed of 60 mph was specified. No. 16 was brand-new when it made its demonstration run for the LPTB, and had not even been handed over to the GWR by the builders.

One of those present on the trip was George Hally, formerly CME of the Metropolitan Railway. He reported to the LPTB in such favourable terms that it was considered worthwhile trying out an experimental railcar service on the Chesham Branch to see if it justified a wider application of the idea. In May 1936 therefore, it was decided to buy two AEC railcars (one in service and one spare) at a total cost of £12,000. It was said that if the experiment were successful, more cars would be purchased for services north of Rickmansworth. They might also be used on the Rickmansworth to Watford shuttle service, although this was already electrified. With the planned take-over of through, steam-hauled services from London by the LNER, steam locomotives operated by the LPTB could be eliminated.

When firm estimates from AECs arrived in June 1936, the price had risen considerably from the original £12,000 and now stood at £18,000. Much of this increase was due to changes proposed by the LPTB, which included an all-steel body, Westinghouse air instead of vacuum brakes, automatic couplers and air-operated doors. The body design had not been finally settled at this stage and two versions were offered. One of these was based on the Great Western’s “flying banana”, the other on the Hammersmith & City Line replacement stock, or O Stock , as it became known. The latter design was the one favoured by LT, and it was this which was the main cause of the increase in price.

A point which came out clearly in discussions about the vehicles was that they had to match the performance of modern electric stock because it was by then intended that they should work further south over the electric lines, at least as far as Wembley Park. There was talk of increasing the number to be built to six to cover the extra workings. Their main purpose over this section was to cover lightly-used off-peak services. There was however, the question of reliability and maintenance, about which little was known, and it was therefore considered preferable to restrict the initial purchase to two in order to gain some first hand experience of their operation.

Price negotiations with AEC continued. It soon became apparent that they had actually lost money on the GWR orders and that the original quote to LT of £12,000 had really only been bait to get them interested. In spite of an offer of a price reduction of £700 per car and the withdrawal of the auto-coupler idea to save more money, a new price of £16,500 was still considered too high. As a result of these escalating prices, a reassessment of operating costs north of Rickmansworth was carried out and it was realised that there was now little difference between the proposed diesel traction and the existing steam service. Surprisingly, in view of earlier misgivings, electrification was now shown to be the best financial prospect.

A very quick about-face by the LPTB re-activated the agreement over electrification obtained with the LNER early in July 1936 and, on 7th August 1936, the diesel scheme was officially dropped. AEC was told “thanks but no thanks” and was paid £220 for its design work. With that, the idea of a fleet of “O Stock”-bodied diesel railcars running over the Metropolitan between Wembley Park, Watford, Chesham and Aylesbury disappeared, almost without trace.

Thanks for that TP...I had forgotten about the O-Stock version.

The photo I have seen can be dated: "from June 16th to June 27th 1952 the cars worked Mondays to Fridays as part of the shuttle service over the then steam- worked, Epping to Ongar branch".

As you all know by now, in the early Eighties LT was considering purchasing up to I believe six ex-BR Class 25s for infrastructure work. Indeed on was trialled on the Uxbridge branch and was photographed at West Harrow. I gather, and TP may know better, that LT were concerned that these locos were cream-crackered, and BR wanted too much for them...£100K each was rumoured. I have just found that this may have been 1982:

"The New Year revealed a depressing scene at Derby Works with only seven locomotives undergoing repair. The only Class 25 present for repair was 25262, category N4. However the Works would soon see the influx of a number of Scottish Type 2's for repair, caused by a maintenance backlog in Scotland and the effects of the continuing harsh weather. At Swindon interest had been shown by London Transport in possibly acquiring three Class 25 locomotives, however nothing concrete materialised from this idea, although possibly 25246 & 25305 were set aside in the North Yard following from this enquiry."

Obviously these would have required tripcocks, as had the BTH Class 15s as mentioned.

Isn't it amazing how much info is available out there if only one had access to it. Thank you all !

The low initial price to lure in buyers certainly worked with the GWR as they finished up with 38 (?) of them and their's worked efficiently and lasted into Nationalisation. Who knows the other Railways might have become interested as they were already playing around with One - offs.

With the comparative success of their Battery Locos I wonder why the LT didn't consider Battery Railcars , topping up at Epping or Chalfont during layovers.

Not just West Harrow. These photos, on the LT Museum Website, show the beast in Uxbridge Sidings on 17th December 1981.

Class 25306 (1)
Class 25306 (2)
Class 25306 (3)

Oh and this picture was taken at the same place on the same day

Lost Train

They do indeed still act in tandem today

Well, er, not exactly. I must correct this. The tripcock was usually just a lever at the end of a pipe connected to the vacuum on the loco. Now, from my limited experience of driving steam locos, I know that many only had steam brakes so, on some, the vacuum tripcock only operated on the train. As the loco was usually as heavy or heavier than the train, the stopping power was a bit iffy.

The tripcocks were also subject to almost no maintenance, so Leslie Lawrence was right to be cautious.