Sunday, 4 September 2011

Summer Saturday with a '2884'

Mike and 3803 ready to come 'off shed' at Shackerstone.

Former Great Western 2-8-0 locomotive number 3803 has been a popular performer at the Battlefield Line this summer. My first rostered turn was on Saturday 27th August 2011 when the locomotive was required to make five round trips to Shenton with a 5-coach service train. Mike was 'marked' as fireman, Danny (who'd recently passed out as a fireman) was also on hand and Danny's sister had the cleaner's 'spot'.

The locomotive had been left with a warming fire on Friday night so it was possible to clean the grate and resuscitate the fire with wood and coal. It's a big boiler so we were anxious to bring it into steam gently to avoid the rapid expansion which can increase maintenance costs through the increased stress on rivets, stays and smoke tibes. In the meantime, I got on with oiling round and the driver's daily examination of the locomotive. Outside cylinders mean that quite a few oiling points are accessible from outside but the link motion between the frames (see 'Layout of Valve Gear' below) requires you to lean in (or climb in) from the footframing to attend to some of the oiling points.

We were ready in good time, came 'Off Shed' and coupled up to the 5-coach train in Platform 2 on a nice, sunny morning. We set off, tender first, and I was at once impressed by the power and smoothness of the locomotive. Although running tender first, the low Great Western tender gives reasonable visibility to the rear, provided the coal isn't too heaped-up in the tender. I was obviously comparing this Swindon product with the Stanier '8F', about which I'd commented "The standard Stanier tender is not ideal running tender-first as far as visibility is concerned, so it's particularly important that the driver and fireman work together as a team." (see full article).

On my first trip with '3803', I drove fairly cautiously whilst I got the feel of the unfamiliar locomotive. As is my usual practice, as soon as we were moving, I linked well up on the 'pole' reverser to a position sutiable for drifting. The effort required to adjust the reverser was very moderate, as you'd expect with Piston Valves (which are 'Balanced' valves, unlike standard Slide Valves). With our featherweight train, acceleration was still good linked-up and, when we reached line speed, I could simply slam the regulator shut, re-open it on the 'Jockey Valve' (to make sure there was still a steam supply to the Sight Feed Lubricator - see below for further information) and coast. However, I was disappointed to find I was losing time. I'd been warned that I'd have to run fairly hard to keep to time now that trains are making a stop at Market Bosworth station. In addition, there are still a number of 'slacks' (speed restrictions) of 5 m.p.h. and 10 m.p.h. to be observed. We arrived at Shenton, ran round our train and set off back to Shackerstone, chimney leading.

On the approach to Shackerstone, the engine crew are always on the lookout for the Outer Home signal. The road bridge in front of this signal means that the sighting distance is reasonably short. If the arm is horizontal (nine o'clock clockface), the signal is 'On' and the train has to stop at the signal. If the arm is raised through 45 degrees (ten thirty clockface) the signal is 'Off' and the train can proceed to the Inner Home signal near the signal box. During the hot weather, it's been common for the signalman to struggle to give the correct 'Off' indication but on this day, I'd commented to Mike that we were getting a good 'Off' indication.

Shackerstone's Outer Home (lever 2) 'On'.

Back at Shackerstone, we ran round, and started our second trip of the day. Now the temperature dropped and it started to rain quite heavily. I'd taken the precaution of bringing a waxed jacket but the rain seemed to be coming horizontally across the low tender as we made our way to Shenton. As I squinted into the rain to 'watch the road', I remembered my own saying "Anybody can work on engines in good weather - it takes railwaymen to do it in bad weather". Many locomotives had 'Storm Sheets' which could be rigged between the cab and the tender to give some protection. I gather one had been ordered for '3803' but had not yet arrived. We used to keep storm sheets on the Great Western tender engines at Tyseley Railway Museum, but I was never too keen on using them myself because they do inevitably somewhat restrict your lookout running tender first.

One the second trip, I ran a little harder and just about managed 'even time'. Approaching Shackerstone's Outer Home on the return journey, the drop in temperature had tightened the signal wire and this time, the arm was almost pointing straight up. "If it gets any colder, the arm will be over the top" I joked, telling Mike about the time that happened to me on the 'Big Railway' (one of the 'Recollections' in the article on Tipton Curve Junction).

It was agreed that Mike would have a break for lunch and Danny would fire the third trip. Once again, we made the run to Shenton, ran round and returned chimney leading. The rain was still pretty bad. The Great Western did have large, sensible hinged spectacles at the front of the cab (visible in the heading photograph). Stanier lost no time in using a similar spectacle on his designs for the L.M.S. after he moved to Derby. I'd been running with the driver's spectacle open but an awful lot of stinging rain was being thrown into my face so I slammed the spectacle shut. Within seconds, there was so much rain streaming down the outside of the glass that I could see nothing ahead, so I reverted to running with the spectacle open.

I made the usual cautious approach to the Outer Home at Shackerstone and, to our surprise, the arm was at about one o'clock clockface. My prediction had come true, the arm had gone 'over the top'! This counted as a signal aspect "imperfectly displayed" which should be treated as a danger signal, so I brought the train to a stand. It was still raining quite hard but Danny made no complaint at the prospect of walking to the signal box to advise the signalman and obtain his instructions. Danny returned with permission to pass the signal and we made our way into the platform. I'm sorry I didn't get a photograph of the arm in the odd position.

Mike came back on the footplate and we completed our last two runs in rather better weather. Danny attended to the Outer Home so, when we returned to Shackerstone on the fourth trip, we received a proper 'off' indication. We enjoyed a pleasant fifth trip and disposed of the locomotive after an excellent day.

Background to the '2884' class

One of Churchward's original designs for the Great Western was a 2-8-0 for heavy goods work. The first locomotive '2800' was introduced in 1903 and the build totalled 84 locomotives. The '28XX' class was a great success and so when Collett, Churchward's successor as Chief Mechanical Engineer at Swindon, needed more heavy freight locomotives in the run-up to the second World War, he continued to build the Churchward design with very little change. The standard Collett cab, with glazed side windows, was the most obvious improvement. The numbering carried on from 2884 to 2899, then continued from 3800 to 3866. The Collett engines are often called the '2884' class.

The Great Western had published the first of its 'Engine Books' in 1911 and periodically this was updated. The 1946 edition (priced at two shillings and sixpence) included the page reproduced below describing the 2-8-0 tender engines (this is taken from the David and Charles composite edition of 1971, ISBN 0 7153 5367 5). Note that the official works photograph of 2840 shows the original Churchward cab but the lower line drawing depicts the Collett cab.

Click on the above image to enlarge.

Layout of Valve Gear

All the 2-cylinder Great Western designs feature Stephenson Link motion with four eccentrics mounted on the driving axle between the frames to provide the necessary valve events. With inside cylinder designs, the valves are usually between the frames and can be readily driven from the expansion links via the dieblocks and valve rods. However, where outside cylinders and valves are required, a means must be provided to translate the movement of the dieblocks from inside the frames to outside the frames. Swindon devised a typically rugged arrangement using rocking shafts which is illustrated below.

Click on the above diagram to enlarge.

In this arrangement, the dieblock is attached to an Intermediate Valve Rod, the lower end of which is supported by a swing link. The upper end of the intermediate Valve Rod is attached to the inner of two valve arms attached to the rocking shaft mounted on the framing. The upper end of the intermediate valve rod describes an arc when driving the rocking shaft, necessitating the swing link at the lower end to accommodate this non-linear movement. The outer valve arm drives the short valve rod which connects to the valve spindle. The set of pictures of 3803 (link below) has a number of pictures of the valve gear illustrating how the layout in the diagram above is implemented in practice.

Sight Feed Lubricator

Moving parts in contact with steam (such as the valves, pistons and regulator valve) require lubrication with a special, compound mineral oil, formulated to retain its properties at high temperature. Sight feed (or hydrostatic) lubricators are often used for this purpose and Swindon developed a range of suitable lubricators. Whereas many railways left the management of these lubricators to the fireman, the Great Western placed the Sight Feed Lubricator in front of the driver. Through training and the issue of circulars, Swindon ensured that drivers understood the method of operation and the importance of the Sight Feed Lubricator. A copy of Great Western Circular 5801 issued in November 1937 by C.B. Collet can be accessed (and downloaded) here.

My pictures of 3803 are here.