Saturday, 25 May 2019

Hello Dolly!

If you go back to 2/11/16 you may recall why the 4415 project team does not provide horse racing tips; having considered putting money into three different Diesel engines we decided to back the horse with the broken leg. This ‘horse’, the MDB4 engine had damage to the crank case, a broken crankshaft, a damaged piston, no injectors (atomisers in the language of 1928) and no fuel pump. While we have a very comprehensive set of drawings for the locomotive and some drawings for the engine, the set of engine drawings is incomplete. The drawings we have come from the McLaren archives held at Armley Mills museum, who also kindly donated the MDB4 engine to the project. In the back of another of their sheds was something to covet:

This particular wonky donkey of a horse is a Barford Perkins road roller. Precise vintage unknown, but the interest from the 4415 project perspective is that the motive power comes from a McLaren MDB2 engine, the two cylinder variant of the MDB4. The great thing about the roller engine is that it is substantially complete, with fuel pump, governor & atomisers. Obviously (by definition) there are not enough of the components the project needs for cannibalisation, but cloning is the technology of the future.

In line with the project ethos, recovery of the roller was done by the team in some style, that style being provided by Foden, courtesy of Dave Walker.

For the roller, there must be a sense of déjà vu, it does not look any happier in its new home in Wales:

The continued support of the Armley Mills museum to the project is greatly appreciated. The roller is on loan, to enable investigation and replication of the components missing from the MDB4 engine. The governor/ fuel pump assembly (in the photo below) is of particular interest and can be compared with illustration of the MDB4 from "15/- change":

When the two photos are compared, the fuel pump assemblies can be seen to be similar, but not identical, and it is not just that one has two fuel lines running from it and the other four. It might be because some of the McLaren drawings we have for the fuel pump are labelled ‘for Old Type Fuel Pump’ which infers that there is a new type too. We have some detail drawings and can be very confident that we can recognize an old type governor ball thrust when we see one; whether we can tell if the MDB2 fuel pump is ‘old type’ or ‘new type’ will require some expertise that merges the roles of diesel fitter & chicken sexer, and the governor ball thrust is very much an integral part of the whole fuel pump assembly.
Whether the drawing below represents the ‘new’ or the ‘old’ type unit we do not know, but there’s quite a bit of work in making one of these.

 We’ll keep you posted on progress.

The other main items of interest are the atomisers. We do have a good set of drawings for these, but it's nice to actually see one.

A reminder: MDB2. It has two cylinders and therefore two atomisers. It would have been nice if they were both the same; but which is the new, improved one?

The ones we are going to have made are the ones on the right; because we do have a set of drawings for that type.

Not all the bits that need to be cloned are complex precise bits of machining. We also need some interesting castings too. This is a rocker cover from the MDB2. We need four of these. We’re pleased to welcome Bob Smith to our team, with the hope that he will enjoy the title of ‘project patternmaker’, because this isn’t the only casting we need.

Finally from the roller, something that rocks our world. Proof that the pattern shop at McLarens did not have a proofreader. We don’t need to clone the radiator, but we do need to clone the spelling mistake:

Tuesday, 5 February 2019

Gearbox fitted!

Rick, Matty & Monkey have overcome the interface issues which left the gearbox on physical chain block and storyline cliff hanger in the last report. Overcoming the interface issue, meant a trip for the clock side mounting plate.

In this view of the gearbox being finally lowered into the frames, the fact that the engine and gearbox are not on the centreline of the locomotive is all too apparent.

This photo shows the final drive gears (external to the gearbox) and the drive chain from the layshaft to the leading axle and gives an idea of how little room there is between the gearbox and longitudinal frame stretcher to squeeze the new clamping plate in. 

On the engine side there the clamping plate is positioned outside the frame stretcher (hence the need for the spacer ring described in the 11/10/18 report. As it is a new component the clamps are assembled with metric bolts.

There is a cast iron spacer which sits on the layshaft and holds the gearbox in place laterally. This has been trimmed back, so that it now locates on the clamping plate rather than the gearbox. Two flats have also been machined off to allow the spacer to fit between the clamp plate bosses.

With the gearbox now fitted the interior has been cleaned up. While the working of the gearbox was described in the 6th December 2017 report, it will not harm to describe it again. By moving the bevel gears on the upper shaft to the left or right (so that they engage with the unseen gear on the incoming drive shaft) the upper shaft can be made to rotate clockwise or anticlockwise. The motion is transmitted by chains to the lower shaft. On the bottom shaft whichever dog clutch is engaged determines if you are in the high or low gear.

Close up of the lower (speed) shaft. The splined output drive shaft cab be glimpsed between the dog clutch teeth on the left hand side. The selector (see image below) engages with the central groove to move the clutches left & right.

Close up view of the forward/ reverse gears. No work has been done to these gears, other than a clean-up.

Gearbox with chains and selectors re-fitted.

Crank operating the high/low gear selector, possibly made at Britannia Foundry (see 6th December 2017 report).

Oil filler re-fitted (original pot, replica cap, see 24th June 2017 report).

Matty eschews Ricks handiwork with the oil filler and pours another 5 gallons of oil into the ‘box.

Another milestone reached!