Dr David Rae

Does a fascination with a minor, rather odd-looking type of locomotive often endure from youth to middle years? I first came across a mention of the Sentinel Shunter as a boy, reading the December 1970 Airfix Magazine for plastic modellers. I still have my copy.

Amongst the normal diet of aircraft and tank kit conversions was an article about building a OO scale Plastikard kit of an LNER Y1/Y3 Sentinel shunter onto a Tri-ang motor bogie. For some reason, possibly its boxy simplicity, this captured my imagination. I never found the kit but when I acquired a grindy old motor bogie I built a succession of overscale bodies to run on it, first cardboard and then Plastikard.

One fact neither the article nor the kit got right was claiming the LNER painted its Sentinels in apple green livery…but read on. Some years later, I photographed and even ‘cabbed’ the sole surviving LNER Y1 at its home on the Middleton Railway, marvelling in the clubby humid atmosphere of the cab with its evocative smell of warm oil, toasting coal and steam.

About the same time, I obtained a copy of the reprinted Sentinel Patent Locomotives which included a selection of the wide variety of Sentinel locos and railcars, and this is the main source for pictures of the CE locomotives. I even acquired a Nu-Cast OO kit for the Sentinel shunter and was surprised by how tiny the plastic body parts were – much smaller than my youthful efforts. So when a ready-to-run O gauge Sentinel shunter was announced I nearly ordered one, as I had recently started to become interested in railway modelling after a lengthy break to pursue a career. However I had started dallying with O gauge, and found that I could build a Sentinel kit in this scale much bigger and chunkier than the OO version, for under £100 all-in.

Thank you John at Walsworth models. This turned out to be an LNER Y3. I’d also become interested in the Derwent Valley Light Railway, rediscovered after visiting it after an Easter York show, and bought Branch Line to the Derwent Valley which was much-read and inspired the idea of a small layout based on the DVLR. This became the Coney Hill Light Railway. I had already acquired an unbuilt Westdale kit for a Sentinel railcar, including a motor bogie. This bogie turned out to be a factory-built Walsworth Y1/Y3 chassis, too long to fit in the railcar and with wheels too small. The railcar will have its own motor bogie built in due course. So what to do with a perfectly good Sentinel chassis?

• The options seemed to be building:
• another Y1/Y3 – too repetitive
• a Y6 tram loco – which just would not look right
• The DVLR‘s own Sentinel – the natural solution.
  

More investigation of the DVLR Sentinel showed it was of interest in its own right, but photos are scarce. It was one of the series of CE (Centre-Engine) class Sentinel shunters built in 1925-26. The CE locos were forerunners of the later LNER locos, as illustrated in the picture of the Leys Malleable Castings loco (works 5733 of 1925) which seems to have been the very first. Abbott’s (1989) book Vertical Boiler Locomotives has a complete Sentinel works list which shows a run of about 13 of these locos built in 1925-26.

These were purchased by a variety of industrial and minor railway companies and included several Welsh quarries, Indian railways and the LMS (NCC). The DVLR example carried works number 6076 and is dated 4/1926 in the works list. However its place in history records that, shortly after delivery, on 25 May 1925, it hauled the LNER dynamometer car on the DVLR, and convinced Nigel Gresley that its steady chain-driven propulsion was ideal for light branch lines and sidings. The result was an order for LNER 8400, the prototype of the later Y1/1 design.

The side view of 8400 in Yeadon’s volume 12 (p10) shows that this loco, different from all those which followed it in classes Y1/Y3, was identical to the others in the CE batch (although they had detail differences) and similar to the DVLR loco. The CE class had a lighter frame section with cut-outs at each end for the sandboxes. The rather quirky bodywork had a quadrant fillet between the cab vertical and horizontal bunker panels, higher cab eaves and lower side windows than the later Y1 design.

It seems that the CE class ended with 8400, with subsequent locos of the Railway type being built instead, similar to the Y1, such as the preserved Isebrook which was built for the GWR.

One fact we probably know about the DVLR Sentinel is that it was painted light green – one source recalls it being in NER green, with straw DVLR lettering shaded in black, although a person who saw it when a small child recalls it being silver-grey. So a green Sentinel is possible after all.

However it did not last long, for after enabling the DVLR to run trains more cheaply, and possibly even hauling the final passenger train in 1926, it proved unequal to the increasing volume of freight traffic being generated and was sold on to a contractor in Darlington in 1927. It was not scrapped until 1970.

I made a working drawing of the CE class, using dimensions from drawings of the Y1 combined with details and variations from the photos above. It is not 100% accurate but useful as a guide. The model is built from plastic sheet and Plastikard. At first I mocked up a quick dummy from cardboard which showed problems and mistakes in the height and window spacing. These were corrected before the parts were cut for the final model. Then the frames were cut from 0.060in plastic sheet, covered with 0.010in layers embossed with rivet detail, and mounted on the footplate which is 0.040in sheet and are similar to the buffer beams which were also covered with riveted 0.010in sheet.

The body sides and ends were cut from 0.040in Plastikard and these were detailed with narrow strips of 0.010in for the panel beading. The window beading was formed from thin florists wire after micro-rod proved a bit reluctant to take exact 90 degree corners. The cab end and bunker ends were assembled and the distinctive curved corners formed by filing and sanding; these are reinforced inside with spare sprue and styrene offcuts.

The detail fittings would have taken valuable time to build, but fortunately John at Meteor Models kindly agreed to let me purchase whitemetal castings from the Y1 Sentinel kit for the axleboxes, sandboxes and buffers. These may not be 100% accurate for the CE type, but by this time (the Cleckheaton show in June 2013) I was aiming to complete the loco for the DVLR Centenary Gala at the end of July, so using these enabled this target to be met. The body is well weighted with lead, in the bunker, cab corners and a roll in the plastic boiler drum which is the only internal detail.

Having built an upright 2 cylinder engine, brake standard and reverser for the Y1, I knew that none of these are visible on the completed model. Finally the cab roof was shaped from 0.020in Plastikard and reinforced with eave pieces. Then the body was brush painted with Phoenix NER green, the frames being black, a grey roof and buffer beams matt red. DVLR lettering was added and light weathering on the frames, buffer beams and roof. Finally, Tamiya matt varnish gave a good finish.

The little loco was finished in time for its debut running on Coney Hill at the DVLR Centenary Gala, which was a memorable event for all the right reasons. As a model loco it is an unremarkable Sentinel box, but the experience of researching and building it was an enjoyable challenge.

References: Sentinel Patent Locomotives, EP Publishing, 1974 R.A.S Abbott, Vertical Boiler Locomotives, Oakwood Press, 1989 Yeadon’s Register of LNER Locomotives, volume 12, Railcars & Sentinel Shunters, Book Law, 2003. We anticipate the new book Rails along the Derwent Valley, Holne Publishing, 2013 may have content on the DVLR Sentinel.

David’s review of Rails along the Derwent Valley appears in this issue of the Gazette