Drag Boxes

Photos by Rob Bishop

The lack of recent news does not reflect a lack of recent progress. This report focuses on ‘new’ construction. KS4415 has never had a ‘drag box’ per se, merely couplings and buffers attached to the buffer beam. In early 1929,  KS4415 was fitted with chopper couplings to allow it to be used on passenger trains on the WHR. This is the period the restoration aims to represent. How the chopper couplings were fitted is unclear. Getting the coupling arrangement right is essential for the safe operation of the locomotive so we are shamelessly adopting current technology. To provide an idea about what we are currently fitting, here is ‘the answer’, in this case fitted to new FfR observation car 152.

Dragbox Assembly Car 152

The drawbar pivots in a crosshead. The crosshead is supported on two large bolts, with a series of rubber pads providing springing for both haulage and buffing loads. On KS4415 space to install this arrangement is limited, so rather than being fixed to a frame stretcher the dragbox assembly will be fixed to a strengthened buffer beam.

One of the crossheads for KS4415

The bufferbeam marked out for the new slot
to accommodate the coupling

Spare’ holes welded up, and new slot cut

A doubling plate has been fitted inside the frames

Having welded the old holes up Matty Wolstenholme drills
 a new row of holes. These will be used to rivet a pair of angles
 inside the frames which will carry the dragbox.

New holes, meet old holes

The angles used to fit the drag boxes to the frames
have been riveted in. The two bars labelled ‘top’ and ‘bottom’
are the start of the dragbox and are bolted to the angles.

The rear unit is more bijou.

Update 8th March 2017

Photos by Rob Bishop

In the last update the transmission brake received a mention. Despite looking quite fossilised, it stripped down nicely and all of the components are reusable.

Transmission brake dismantled

The subframes have now been fitted and the grey top coat applied. This view looking to the rear of the frames clearly shows the rear frame stretcher repair and also the repaired areas of the sub frame.

Subframes looking back

This is the view looking forward, showing more of the sub frame repairs and the various brackets which carry the brake gear, with the slot and cut away section of the frame where the transmission chain from the lay shaft comes back onto the leading axle.

Subframes looking forward

Assuming that you are interested in watching paint dry, here is an overall view of the chassis. The 1 ½” hole in the frames at 5 o’clock to the large layshaft bearing hole is to take the ¾” bore pipe which connects the exhauster to the train pipe. 

Chassis side view

The ‘T' which protrudes through this hole, can be just seen in this 1929 view (now located at 11 o'clock to the layshaft), with a witness streak ‘crying’ from it .

1929 view

This interesting assembly came with the MDB4 engine from Armley Mills and is part of the starting mechanism, which is located in the cab below the radiator. I’m struggling to recall how it all works, the upper shaft (with the square end) is in line with the Diesel engine crank shaft, while the lower shaft is connected (via a chain drive) to the Blackburne donkey engine. If you put the starting handle on the upper shaft you can turn over the Diesel engine, but by disengaging a dog clutch you can use the same handle to start the donkey engine. The outer rim of the lower gear wheel is part of a band brake; the strap for which is in situ below the wheel. When this brake is applied, via a small handle (missing, but pivoting in the bracket bottom left) the drive from the Donkey engine can then be used to turn over the Diesel. I’m aware that I have missed something out here, it will all become clear in another thrilling instalment.

Starting mechanism

Getting back to a specialism we all understand, here is more paint drying, this time on the axle boxes & handbrake stanchion.

Axle boxes and stanchion newly painted

A Removable Panel

Drawing, by Kerr Stuart, Photos by Emily High and Rob Bishop

We have, at long last reached the end of the frame repairs. At some stage in the past a section of the front, drivers side frame was made removable, possibly by Hunslets before the loco went to Mauritius. The Kerr Stuart frame drawing has a note ‘see HECo’s (Hunslet Engineering Co) drg No 30931 for alts to frames of L4415’. We don’t have a copy of that drawing, but the frames do not appear to have received any other modifications. The removable panel can be seen in the photo below, with the lay shaft bearing central in the panel. 

When you see what is behind the panel, the benefits of making it removable can be appreciated.

The photograph above is taken looking down into the frames from the front buffer beam, driver's side and shows the components located on the layshaft. From left to right can be seen the gear box, the front longitudinal frame stretcher, the spur gears taking the drive from the gear box to the lay shaft, the lay shaft chain sprocket (note the chain shaped wear on the hole in the stretcher behind) and the transmission band brake. All of this is contained behind the removable frame, and given that the sleeve which contains the lay shaft extends for the full width of the loco, getting at these components without the removable panel must be a nightmare.

So, non-original it may be, but retention is the way forward.

This is the frame extension, with the holes being tidied up on the radial arm drill.

The holes have been modified to take plough bolts; these have a counter sunk head, 

but a square on the shank to stop them turning when they are being tightened.

The frames with the removable plate re-fitted

Before the frame was re-fitted an opportunity was taken to ream out the bracket 

for the transmission brake and fit a new pin. 

The chains did nibble a good bit out of the frames (top right)! 

It is interesting that the opening in the frames have been flame cut

The Vacuum Exhauster

Drawing by Kerr Stuart,  Photo by Rob Bishop

In February 1929 KS4415 was fitted with vacuum brakes to allow it to be used on the thrice weekly Dinas to Beddgelert winter service. While there are no photos of it working these trains, the vacuum pipe is very evident in the series of photos taken of the loco in Minffordd yard later in 1929. Fortunately Kerr Stuart produced a series of drawings detailing the modification. An exhauster was formed using a Blackburne 500cc engine ‘complete without timing gear and other external fittings’. The ‘other external fittings’ presumably being the carburettor and magneto.

A second drawing details the various valves and mounting brackets required to turn the ‘4HP SV Blackburne Engine’ into a vacuum exhauster. 

Isn’t eBay a wonderful thing! You can buy anything on line these days, even small single cylinder engines from manufacturers who ceased trading long ago. This a 4HP, 500cc Blackburne side valve engine:

It needs some attention, and a chain drive from the gear box. How effective it will be as a vacuum pump we will find out eventually, and whether it can really cut the mustard is in the lap of the gods. One of the challenges of exhausters driven off the engine is their (lack of) ability to create adequate vacuum on tick-over. That’s why when you see ‘Mary Ann’ on a passenger train it is revving its nuts off in the platform just to maintain 21” of vacuum. Once you get going the exhauster pulls 25” and will suck the world inside out. The Kerr Stuart arrangement is driven off the gear box. This means that when you drop the revs and dip the clutch the exhauster is not working at all. 

Having a stock of newspaper and leather bootlaces will be a must for the toolbox. For non-believers, that’s technical advice from the Reverend Awdry on how to remove leaks from train pipes .   

Brake work

Photos by Rob Bishop


Rick and Matty's two-man working party is forging on with the restoration of the brake gear. This is a ‘top down’ overhaul, starting with the brake handle.

Before restoration:

After restoration:

The cap to the stanchion itself was very corroded, so this has been replaced:

And the whole assembly has been painted:

Reaming out the arm on the brake weighbar shaft:

The handbrake column connects to the weighbar via a slotted link,  not strictly necessary on a loco which also has a handbrake, but an essential feature if you have a powered brake. The drawings confirm that the steam powered locos which used the same chassis were fitted with steam brakes.

The slotted link needed machining out to accommodate the larger pin required because hole in the weighbar shaft had worn oval, a defect rectified by the reaming:

The completed sub-assembly:

One of the bearings which carry the weighbar shaft being bored out:

The completed weighbar re-fitted to the frames: 

(As the frames have already been orientated for a loco working in the southern hemisphere the whole thing is upside down to northern eyes)

The drawing below has a local orientation showing progress and the inter-relationship between the various components - they are all situated below the cab floor.

The leading brake pull rod has seen better days, but nothing that cannot be sorted out with gas and gentle persuasion:

For a job like this, it helps if you have three legs for some reason:

Some gas, a die nut and an amputation later:

Axle boxes

Photos by Rob Bishop

Last month's engine news was a slight diversion from the main focus of activity,  the restoration of the chassis. With the cylinder block and crankcase dispatched to Cast Iron Welding Services, the volunteer effort has returned to the chassis, or to be more particular, the axle boxes. Over the past weekend,  all 12 of the pins required to attach the radius rods to the axle boxes have been manufactured:

This means that we now have a full set of axlebox components, and, bar a few bolts (and the wheel turning), all of the running gear components.
The kit of parts which make up a single axlebox are illustrated below:

Which look like this when assembled:

Lubrication is applied via the trimming wool pad & wicks of the Armstrong oilers.
The spring loaded lids on the feed to the under-axlebox reservoirs are a nice little feature:

Engines Update

Photos by Rob Bishop, Matt Wolstenholme, Emily High

Just to pick up briefly from the last report with some chassis news: ‘while your wheels are important to us, they have been placed in a queue’ - so they remain sat in the yard at Boston Lodge waiting  for a turn on the wheel lathe, behind an NNG16 Garratt (which has a lot of wheels) and a tram from Beamish.  As one chapter enters a state of hiatus, another one begins.

Engine news and a brief history lesson  

KS4415 is of course a Diesel pioneer, and when built was fitted with a 60HP 4 cylinder McLaren- Benz MDB4 engine. The reference code is an acronym; Mclaren Diesel Benz, with the 4 a reference to the number of cylinders. McLaren also produced similar MDB2 & MDB6 models. The MDB4 in KS4415 was replaced in 1945 by an 80HP McLaren MR4 (one of the differences being the use of a Ricardo whirlpool head). The MR4 looked rather derelict when the loco returned to the UK and it was clear that restoring it would take a considerable amount of effort. 

MDB4 engine

MR4 engine

In 2007 another 1945 McLaren egine was acquired, a 90hp M4 Mk2. The M4 engine (which was once part of a standby generator set) was the one which the team had running at the 2014 Superpower weekend. Although of the same vintage the M4 and the MR4 do not appear to have very much (if anything) in common and on stripping the loco it became apparent that the M4 will not fit inside the loco's frames; the sump of the M4 is massive.

M4 Mk2 engine

The narrow, automotive type sump of the MDB4 & MR4 can be appreciated in these views, in comparison with the huge square lump of the M4. Both the MDB4 and the MR4 sumps are a similar shape and the mounting bolts for both engines are in the same location. The photo of the MR4 shows the engine in situ, supported by two steel channels above the floor plate. The big issue with the M4 the amount of original material which needs to be cut away to lower the engine down so that the centre line of the engine is in line with the gearbox.  This includes frame stretchers (which pick up the sub frame) and also a bracket for the brake gear which is hung from the floor plate.

Restoration of the MR4 has been contemplated. However a rumour that Armley Mills Museum in Leeds had an MDB4 in store proved to be true. After some patient negotiation we now have agreed a loan of this engine (which is also in need of restoration). Fitting the MDB4 will allow the locomotive to be restored to its original condition. Exciting stuff!

The MDB4 has now been stripped down. This has revealed damage to both the cylinder block and the crank case that originated from a catastrophic failure of the crankshaft. So of the 3 engines we have, the one that works (M4) does not fit and the MDB4 is in far worse condition than the MR4 it arrived with. But the MDB4 is a very rare beast and the opportunity it provides to return the loco to original condition is compelling, so despite it requiring the most work this is the horse we are now backing.

The crank shaft of the MDB4. 

Drive to the gear train which powers the fuel pump and valve rockers to the RHS. 

Output to the flywheel lying forlornly in the middle  -  this should be on the LH end of the shaft. 

If you are thinking that these minutiae only appeal to blokes in dirty macs, you could well be right. 

Rob Bishop steam cleans the cylinder block while Dave High cleans the sump.

Unsurprisingly the pistons had seized in the cylinder block. 

One has a chunk missing out of it

While three of the pistons yielded readily to a bit of gentle jacking, piston four took more persuasion. 
The photo of the Wolstenholme patent piston puller doing its thing undersells the two hour application of ‘pocket rocket’, sledge hammers, gas and cursing which preceded it.

One of the MDB4's unusual features is the separate casting on the rear of the engine which carries the cam shaft. Removal of the casting from the cylinder block was relatively straightforward, removal of the cam shaft from the casting less so. 
After a good soak in Diesel and with more ‘Pocket Rocket’ to the fore,
 Matty introduces the cam shaft assembly to the Talyllyn Railway wheel press.

The camshaft, casing and followers await restoration

The sump and cylinder block palleted up and ready for dispatch to Cast Iron Welding Services for repair