There was a 'Gold' footplate experience course booked so I signed on at 06:30. Our lady fireman, Tracey, was 'booked fireman' but on that day she was observing our trainee, Ritchie, with a view to his becoming a 'Passed Cleaner' which would enable him to act as a fireman in his own right in the future. When I arrived Tracey and Ritchie had already done the initial checks and lit-up, so I set-to oiling and examining the locomotive.
An intimation of the problem to come was quickly revealed as I found the left leading spring with a broken 'leaf' near the buckle and the rear portion of the leaf was working its way out of the buckle.
In steam locomotive design, the weight of the engine is transferred to the wheels via springs connected to axleboxes arranged to slide up and down in hornguides attached to the main frames. Some vertical movement of the axlebox is possible as the spring deflects from its 'rest' position', but the tension in the spring then acts as a restoring force to return the axlebox to its 'rest' position. Each 'wheelset' (an axle with two wheels) has two axleboxes embracing two machined areas on the axle (the journals) so that each wheel has 'independent suspension' allowing it to rise and fall, following 'bumps' in the track.
Various types of spring are used but the laminated leaf spring, as used on the 'Austerity' tank, is most common. Two arrangements are possible with laminated springs, depending upon whether the spring is mounted above or below the associated axlebox. The 'Austerity' tank is 'undersprung' where each end of the spring is connected, via links which allow the spring to 'flex', to the main frames and the buckle in the middle of the spring is connected to the bottom of the axlebox.
'Austerity' Elevation showing 'undersprung' laminated springs on each axle (Industrial Railway Record).
This picture shows the (undamaged) spring on the left leading axlebox of 'Austerity' tank 'Royal Pioneer'. The long, round horizontal rod across the foreground is part of the brake rigging.
There were no maintenance staff on duty at Shackerstone and, even if there had been, jacking-up the engine and changing a main spring would have made us very late into traffic, jeopardising both the footplate experience course and the advertised service. Resident Peckett locomotive 'Sir Gomer' was standing next in line in the shed but completely cold. I didn't even consider using 'Sir Gomer' because, even if fit for traffic, the time to bring the cold locomotive into steam would have meant no trains until the afternoon.
In the days of steam on post-war railways various techniques were adopted in emergency to reduce the time it took to make an engine steam but the more 'agressive' techniques tended to reduce boiler life and increase maintenance costs. The coefficient of expansion of metals means that when a boiler is brought to working temperature, the dimensions increase. If this is done too quickly, the stresses on rivets, stays and boiler tubes may result in leaks. I think I worked out that the boiler on a Great Western 'Castle', for example, becomes about half an inch longer when hot (and the design allows the firebox to slide on supports to accommodate this expansion). Some sheds kept a flexible hose attached to a long hooked pipe. The hooked pipe was lowered into the chimney of the engine to be steamed and the hose was attached to another engine already in steam. Allowing steam to flow through the pipe and escape from the chimney provided a draught to 'encourage' steaming in the way that the Blower stimulates the fire on an engine already in steam. Another approach was to couple the engine to be steamed to a second locomotive and drag it up and down the yard with the reverser of the engine to be steamed set in the 'wrong' direction. The cylinders acted as air pumps, pressurising the boiler with compressed air. When the Blower Valve was opened, the escaping compressed air provided a draught to the fire (at least briefly).As an alternative, I found a large sledge hammer and, as carefully as I could, hammered the protruding section of the broken spring leaf back towards its original position. In the limited time available, that was as much as I could do and I decided that I would take the locomotive into traffic and keep my eye on it during the day.
Our driver on the 'Gold Experience' course arrived early and we set off light engine for Shenton, with me explaining the use of the driving controls and the need to comply with the various speed restrictions along the line. We returned to Shackerstone and coupled onto the waiting train. By this time, our 'Gold' driver's family had arrived and they boarded the train as I introduced the complications of the vacuum brake which we'd be using on this trip. We made and uneventful trip to Shenton, uncoupled and 'ran round' then returned to Shackerstone. Our 'Gold' driver had performed well and had clearly had a most enjoyable time. We all said 'good bye', uncoupled, ran round, watered and prepared to take the 11.15 a.m. train which departed a few minutes late.
'Cumbria' ready to leave Shackerstone on an earlier date.
We completed three of the five 'booked' round trips but, by this time, the broken spring leaf had worked its way back out a few inches and my attempts to persuade it to return nearer to its correct position were not successful. Not wanting to risk a complete failure down the line (with the risk of 'stranding' passengers) I decided to 'fail' the locomotive. We believed the Diesel Multiple Unit (DMU) was serviceable so it was agreed that Ritchie would go and start-up the DMU whilst Tracey and I limped onto shed and disposed of the steam locomotive.
I need to introduce a little background here. I have described my previous turn on the DMU on Wednesday 2nd August 2017 in the post Summer at Shackerstone when we were using the 2-car set (51131/51321). After that turn, Ritchie took 51321 out of service for repairs to the roof so subsequent services had operated with 51131 coupled to the single-unit 'Bubble Car' 55005. The versatility of the Electro-Pneumatic control systems allows this sort of unconventional arrangement. However, I learnt that, subsequently, one of the two engines on 55005 had failed and there had been some difficulty in isolating the failed engine.
Like many cars, a Diesel Multiple unit requires a gearbox to match the limited range of engine speed over which an internal combustion engine can provide reasonable torque with the wide range of vehicle speed required. Many of the British Railways designs (and all the examples at Shackerstone) use an Electro-Pneumatically controlled (E.P.) epicyclic gearbox. Unlike cars, a Diesel Multiple unit travels as far travelling backwards as forwards and needs a range of gears in both directions. So, instead of making 'reverse' an 'add-on' to a gearbox, it is made a separate function, called the Final Drive, mounted on the driven axle and also E.P. controlled. The engine always rotates in the same direction and the drive, having passed through the gearbox, turns a Cardan Shaft, again always the same direction. The reversal occurs within the Final Drive unit by operating a selection 'Dog' splined into the input shaft from the gearbox but free to slide so as to engage one of two bevel gears which, via a spur gear, determine the direction in which the axle revolves. The sliding 'Dog' is actuated by a Selector Fork controlled by two E.P. valves.Ritchie completed the fourth round trip with the 2-coach train running on three engines. With an engine 'out', performance is affected but Ritchie found the operation unexpectedly sluggish. By the time he returned to Shackerstone, Tracey and I had completed disposal of the steam locomotive so Ritchie invited me to drive the last train. However, as soon as I started away, I agreed with Ritchie that the unit seemed very 'unhappy'. Having gone barely 300 yards, Ritchie decided that we should cancel the run. We never like to disappoint passengers but, with the risk of failing 'in the section', I readily agreed, 'changed ends' and slowly drove back to the platform to disembark our passengers. Having 'changed ends' again, I then very slowly drove to the DMU siding and Ritchie (who, of course, owns the diesel multiple units at Shackerstone) immediately set-to dismantling the Final Drive and, before long, discovered that the 'Dog' (described above) had shattered, suggesting that permanent isolation might not have been achieved. He removed the broken pieces and decided to remove the Cardan shaft so that the midweek railcar service could continue whilst he arranged the necessary repairs.
To take an engine out of service the Starter Motor is electrically isolated by operating an underframe-mounted switch adjacent to the engine.
55005 Number 2 Engine: The Engine Isolator Switch is the orange-painted square box underneath the wooden footstep.
A failed engine must also be mechanically isolated from the wheels by latching the 'Dog' Selector Fork in a central, 'neutral' position. This is achieved by pulling-out and turning an Isolating Plunger mounted on top of the final drive. A spring then pushes the Isolating Plunger so as to engage in a groove when the Selector Fork and 'Dog' are in the 'neutral' position, confirmed by rotating the Cardan Shaft by hand. The Isolating Plunger is in an inaccessible position almost on the centre line of the vehicle so the Guard's Compartment is equipped with a special long-handled fork (always called the 'Toasting Fork') to assist.
DMU Final Drive: The small rectangular casting near the centre of the picture is the Isolating Plunger. Pulling and turning the bar into the horizontal position isolates the drive.
My post Diesel Multiple Units has links to training material produced by British Railways: black and white sound films and training notes.
What happened next?
I was rostered as driver on 'Cumbria' a week later, Sunday 27th August 2017) and, again, there was a 'Gold' footplate experience course followed by five passenger trips to Shenton and back. Temporary repairs had been made to the spring (tack welding and clamping) and no problems were encountered. I was delighted to be 'paired' with Ritchie, now a Passed Cleaner on his 'maiden' solo firing turn. We both had a very enjoyable day.
I was re-united with the DMU for a 'Midweeek' turn on Wednesday 13th September 2017 with Grant as Guard. The initial problem we faced was that the 2-coach DMU (51131 with both engine serviceable coupled to 55005 with one engine in use) had been 'boxed-in' by a class '04' shunter and a freight wagon. There was no passed '04' driver on site but I was happy to use the DMU to push the vehicles down the 'North End', out of our way. I brought the DMU onto the wagon and coupled on, using the wagon's 'Instanter' coupling in the long position (there's more about the 'Instanter' here). But then we had to release the brakes on the '04'. Brakes on diesel shunters are normally 'co-acting' - they can either be applied by a proportional brake valve when an air receiver is 'charged' (from an engine-driven compressor) or, alternately, manually, (usually from a handbrake wheel in the cab). Neither Grant nor I could budge the handbrake wheel on the '04'. It was clear that the brake had been applied using air and the handbrake wheel then turned to 'take up the slack', resulting in a brake application very difficult to release by hand. It took Grant and I some minutes (using a fishplate as a lever) to release the brake in small steps. Then, with Grant keeping a lookout from the cab of the '04', I propelled the unwanted vehicles out of the way. We re-applied the '04' brake (by hand!), I uncoupled and shunted back to the station with waiting passengers curious about our antics. I think we were seven minutes late with the first departure but, even with one engine out of use, had no difficulty keeping to time for the rest of the day. Grant and I agreed that we'd had a very pleasant day.
Related posts on this website
The 'Austerity' 0-6-0ST locomotive.
To see all my posts about Diesel Multiple Units, select Label 'DMU' or click here.
To see all my posts about the Battlefield Line, select Label 'Battlefield Line' or click here.
My photograph albums
Where necessary, clicking on an image above will display an 'uncropped' view or, alternately, pictures from may be selected, viewed or downloaded, in various sizes, from the albums listed:-
'Cumbria'.
Royal Pioneer (Up close & personal) [Pictures of another 'Austerity' tank].
All my Battlefield Line albums.
