Governor Case Re-build

Well, I've talked about it enough, so now it was time to actually do some work on the governor.

It's quite a lumpy bit of casing with a vertical shaft run direct from the crankshaft up through one side.

The large section at the top housed a set of spring loaded centrifugal weights and the shaft drives the oil pump at the bottom.

Obviously the first job was to strip it down in to its component parts. Then the usual cleaning up, etc, etc. Eventually it turns in to this:

The oil pump was in good condition and just needed a thorough clean up.

Once everything was cleaned up, all of the various component part that required painting had an initial coat of paint. Then it was time to put everything back together.

Ensuring the oil pump had the correct thickness of cover plate joint took a while. To thin and the gears were tight against the cover plate. To thick and there would be to much clearance between the cover plate and the gears which would result in a noisy and inefficient pump. The task was done by trial and error with multiple 0.5mm joints (all hand cut) until the correct thickness was achieved.

New joints where made for all of the other mating faces and, after a bit of fiddling around the final result:

Another bit ready to fit come the time of the great re-assembly.

Photo's

Any regular views may notice that there are a few more photo links.

I had a bit of a sort out of the photo's and have put them in to 10 basic categories.

Ignore the Photo Bucket cr#p and feel free to have a look.

Please let me know if any of the links don't work.

Engine porn at its best!

Edited to add:

A gentle slap on the hand from Sarah (see comments). There are a couple of acknowledgements I should really add.

The photos of the 'National Works' are courtesy of Sarah (NB Warrior). See: http://d3national.blogspot.com/2007/12/national-works-aston-under-lyne.html

The 'Engine Pre strip down' and 'Initial strip down' are courtesy of Lionel Knight: http://d3national.blogspot.com/2007/12/well-i-think-i-may-have-added-some.html

I think the rest are mine.

End Bed

Well, it was a weekend of cutting, grinding and welding. A bit of a change from degreasing, cleaning, stripping and wire brushing!

The result - an engine bed all fabricated up and ready for the re-build.

Its basically fabricated out of 75mm x 150mm channel (that's 6" x 3" in old money). The ultimate plan is to rebuild the engine from the bottom up, direct on to the bed plate. Get the gear box setup and aligned and once all finished and tested, the whole shooting match get transported up to the boat builder and welded in to place direct to the base plate.

Once fabricated, it was time to drill the holes for the mounting bolts. 21" apart and 20" along, 3/4" holes. Using the old adage of measure several times and drill only once, checking the diagonals to ensure they where all perfectly aligned, it drilled some 4mm pilot holes.

Before stepping up to eventually drill the full 3/4" holes; I 'dropped' the bottom end with the mounting legs on to the frame. Theoretically, the pilot holes should have been right in the centre of existing 3/4" leg holes.

Were they buggery!

Remove the bottom end, double check all of the measurements on the bed. Yes, everything was true and square. 21" x 20" with equal diagonals.

Check the engine legs (not an easy task with 2/3 cwt of engine bed floating in mid air on the hoist). Hole centres are 21" x 20". Equal diagonals - NO! The engine legs are pi##ed.

Take the legs off the Crankcase. Yep, they're fine. All of the original locating dowels are in place and true and the legs cannot be put on the 'wrong side' because the dowel won't allow it.

Put the legs back on, bolt them all. Re-check the measurements. Still askew!

Because the pilot holes have been drilled, the only answer now is to get a 3/4" hole saw and (after clamping the engine base to the bed) drill down through the leg holes and straight in to the base.

So much for the science of measuring and drilling as per the 'factory measurements'.

Hey Ho!

Governor and speed control

One of the big outstanding issues is the governor arrangement on the engine. The majority of Nationals and Russell Newbery engines have horizontal governors. Not the case in my engine.

It has its own casing that is mounted on the end of the timing casing and is a vertical arrangement. The centrifugal governor weights are at the top of a vertical shaft (with the connections to the speed controller and the fuel pump), whilst the oil pump is at the bottom.

To be fair, at the moment its a bit of an 'un-known' as to how well it will control engine speed throughout the required range of 250 - 1,000 rpm.

If the engine originated from a generating set, it is almost certainly set up to run at constant speed. The governor then adjusts the fuel rack to ensure a constant speed irrespect of load on the alternator.

On my linkage from the governor to the fuel pump there is a lever and cam arrangement. From what I can work out, this appears to be a rudimentary speed control. But how redamentary is it?

One school of thought is that it may be a speed controller to slightly adjust the 'constant running speed' for frequency control. Say +/- 20 rpm. If that is the case, it may prove difficult to control the lower speed ranges required (but not impossible!).

The other school of though is that it is full range speed controller. This is the one I like because it will work perfectly - forever the optimist! A few clues have revealed themselves:

1. All of the industrial generator sets that I have seen usually have the engine plate marked up as: '##hp at ####rpm' or 'operating speed: ####rpm', etc. My engine plate just gives Engine Type and Engine Number.

2. When I cleaned up the cam linkage it had two marks on it with arrows to a fixed mark. One said 'WORK', the other was unmarked (but why have it?). I'm hoping the unmarked arrow is 'idle'.

To be honest, until the Black Beast is fired up, I'll not know (unless anyone else knows differently??). Even if it is a constant speed unit, a bit a playing with the spring tension and cam profiles should be able to sort it (there goes the optimist again!).

Needless to say, it is now subject if stripping down, degreasing, cleaning, wire brushing, painting etc, etc.

Work and Play

The bank holiday weekend saw a little more progress on the engine combined with a bit of engine orientated socialising.

Sunday saw me pottering up to the Russell Newbery Works open day at Daventry. I wont bore you with to much detail, but rest assured that most of the talk was around RN's, but the National owners (3 of us I think) were present too!

Sarah on NB Warrior has more detail on her blog:

http://nbwarrior.blogspot.com/2008/05/i-can-not-believe-this.html

Note the cock up on the hand over of the pistons and liners - DOH!

What of the engine?

My previous post was about the template for the engine bed. Whilst I was thinking about ordering steel, I also thought about how I would eventually mount the starter motor and fabricate a suitable mounting bracket. The engine was originally hand start only and had a large industrial flywheel with no ring gear. Not to much of a problem as the engine came with a 'marine flywheel that should fit'.

One thing I had never done was check to see if it did. Probably because both of the two mating components (flywheel & crankshaft) were so damn heavy to shift around.

Whilst talking about this, anyone reading ye olde blogg who is considering rebuilding any engine of this ilk, please take in to account the weight of components that you will have to 'move around'. The flywheel is about 2 cwt, the block 2.75cwt, the crank is over 4' long and even things like timing covers make you grunt when you lift them. Every thing takes 3 times as long and twice as much effort!

Don't be put off though, its great fun (in a fairly masochistic sense).

Anyway, The sunshine saw me wheeling out the engine, putting together the 2 tonne engine hoist and lift up the flywheel to offer it up to the crank. Did it fit? Like a glove! The shoulder on the crank matched the recess of the flywheel, as did the bolt holes and diameters.




I then took various photograph and measurements so that I could look at working out how to mount the starter motor bracket (once it was fabricated - which is another job!).

Looking at the above photo you would expect the paint to be in fairly poor condition. Over about 30% of the area it was, the remaining 70% it was stuck like poo to a blanket. I spent a whole day stripping several layers of paint off the flywheel ready for the usual wirebrushing etc, etc. Again a job complicated by having to move a 2 cwt lump of metal around.