Cylinder Review
By Keith Brown

Accucraft Cylinder Replacements

As with most Excelsior's mine has had a dreadful problem with power, in that it really hasn't got a great deal of it.  When I first heard of SM32's new cylinders I thought that this could be the answer to my prayers and signed up at once!  4 months later and the next batch was ready and with money in hand I collected my trophy.

After travelling over to New Milton, narrowly avoiding some maniac changing his wheel in the outside lane of the M27 Paul dutifully handed over my new cylinders, and I dutifully handed over 80.  (Prices have since risen slightly, not surprising when you see the effort that has gone in to making these new cylinders and SM32's other items)

Value for Money

So what do you get for your money?  At first glance you get a pair of cylinders which don't look any different from the old ones, to be honest!  Ready painted in black and slightly larger but otherwise, no different at all. 

You also get a very comprehensive set of instructions which are first glance tend to scare you very easily with talk of removing cab's and boilers and lubricator assembly but which Paul assured me wouldn't cause any problems.  Reassured I headed home, ready to start.

Stripping Down 

The following afternoon I prepared myself for the task ahead by several cups of strong coffee before I began. 

The first essential is to keep all the gubbins you're taking off in some sort of logical sequence if you ever want to put it back together again!  I used several old margarine tubs which are very handy for that sort of thing.

The first step on the agenda is to remove the cab back, which is easily accomplished by the removal of several bolts with the bolt runner you get with the loco.  Not so easy are the two tiny bolts on the side of the cab, which I ended up using a pair of tweezers to remove.  The cab back then falls away, and can be kept safe for later.

Once the cab back had been removed, you can begin to remove the cab innards, regulator, pressure gauge, drain valve and gas tank, all had to be removed before the cab front could be unscrewed and lifted off.  So far so good, thinks I, and stops for a coffee break.

Refreshed and raring to go the next stop was to remove the boiler from the mounting plate, and this was the first real potential hassle as it is held in place with a small posi screw to the front of the rear bogie in a fairly inaccessible place to unscrew it.  A quick curse however and the offending screw joined my growing clutter of removed Excelsior parts.


The next step was the one I was dreading, removal of the lubricator, the lever mechanism from the cab, and the removal of the mounting plate itself, The nut on the end of the steam pipe took some undoing, mainly as I'd blacked out the steam pipe some time ago, and had liberally lashed black paint over all the connections.  The use of two spanners however and it separated from the steam chest eventually.   The reversing lever was removed from the mounting plate by undoing the two bolts and sliding the valve free from the steam chest.  Then 6 bolts later and the whole mounting plate can be tilted forward and slowly pulled back from the rolling chassis itself, being careful not to trap the reversing lever's arm in the process.

Once the steam chest and cylinders are exposed the time comes to start being extra careful.  The first thing is to undo the tiny slotted grub screws on the slide bars and remove them, my right hand cylinder didn't particularly want to part company with the said slide bar and a few muttered curses were uttered before it was prised away very gently..  The next step was to remove the steam chest, so with the bolts removed it was gently lifted up and the tiny grease proof paper gaskets teased away and put to one side, for modification later.  Once the pistons are removed it is essential to keep them protected.  If they get scratched you may as well throw the loco away..  I covered mine in masking tape.

The existing cylinders were then unbolted from their housing and lifted away.  Sean promptly stole them for some project he is working on..  Paul Smith had kindly lent me a ready machined steam chest mounting plate, if not then you have to cut 2.1mm away from each end, not too hard with a razor saw or hacksaw, but I chickened out.  Paul will send you a ready cut item if you send the old one back to him with your payment!!

Once the new one was in place I read the instructions and found that you have to also cut 1.5mm off the posi-drive counter sunk screws hiding the cylinders in place.  Pale and shaken I did the deed, to find that surprisingly it all worked and I didn't break anything.  Phew.

Having wiped my sweaty brow I decided that enough was enough, and came in for tea..

The Next Morning..

The morning broke bright and clear, which meant I had to cut the grass, go to MFI's, go into the loft, open the caravan, go shopping, so it wasn't until the afternoon I could get back to Excelsior.

The first thing to do is to take a craft knife to the old gaskets, this is simply to ensure that they go back on 'true' and don't obscure the steam holes.  The old Excelsior cylinders have two different sized slits to allow the steam to escape, the SM32 ones have the same sized slits for'd and aft, hence the careful cutting.  Following the instructions I simply cut a square out at the rear end of each slit, and hey presto.  If you do tear them then simply make a new set using some grease proof paper, standard A4 paper should also do fine. 

Adding the cylinders to the loco was again child's play, simply bolt them on and there, job done!  The next bit is a bit trickier, and that is to reinsert the pistons and replace the steam chest.

Each piston was carefully inserted into its bore, they are I believe what is known as a 'friction fit' and you may well have to use some elbow grease to slot them in.  Don't be too brutal though!  Once they are in position carefully place the newly cut gaskets onto the cylinder heads and place the steam chest back into position.  Place a screw in each hole in the steam chest and gently tighten.  It is important not to over tighten as I threaded one and had to shoot off to find a supplier to replace it.  I ended up replacing all of them as I couldn't find a matching replacement.  (After all that cutting down to size to..)

Once the steam chest is refitted you can celebrate the fact that you are over half way home!  The next step is to replace the mounting plate and start to rebuild the loco.  I'd recommend a minimal rebuild, just enough to get steam up to test it all out!

I fitted the mounting plate, relocated the reversing lever and refitted the lubricator, gas tank, steam pipe and boiler.  Once all the gubbins are in place it is time to give it a go.

I must admit at this stage that I didn't see Paul's note about having to reset the reversing valve.... I fill the boiler, get everything steamed up and then find I have three speeds, in reverse..  slow, fast and very fast.  Somewhat perplexed I retire to the shed and read the last line of the instructions..  "Refer to instruction booklet on how to reset reversing valve" it says.  Mmmm, I haven't got an Excelsior booklet..  Help!!

It turns out that the Accucraft website has lots of downloadable manuals, and as Ruby utilises the same cylinders as Excelsior that is the one that is needed.  For all you that need it, click on the link below..

I found the my reversing valve only had about 1 turn on the thread and as soon as I adjusted it I ran out of thread.  Something Paul said though which makes life easier is that the reversing lever in the cab of Excelsior can actually be moved for'd and aft several millimetres, which may be all you need, without having to adjust the linkage and valve itself at all.  If you do need to move the actual piston, it may be a good idea to apply some thread lock, as having very little spare thread is apparently a common problem.

As pressure began to show on the gauge I reached for the lever and notched it into reverse.  And lo, it went into reverse, spitting oil about but definitely heading in the right direction.  Moving the lever forward and cor lumme if it didn't go forward to!  I'd cracked it!  After a few moments leaping for joy in the garden I sent it around the track for a test run.

Excelsior crept around the track light engine very slowly, with just a crack on the regulator.  When I opened her up light engine the top speed was very noticeably less than it was with the old cylinders, but it was a realistic speed none the less.  Was I happy?  You betcha!!

I did need to adjust the left hand cylinder a tiny bit to get running to be ideal, but it is always best to try a run first and then start tweaking than to tweak regardless!  I've spoken to Paul and he reckons about 90% of loco's won't need any cylinder adjustment at all.

Please do take some time to get good running in forward and reverse.  The Accucraft loco's tend to run better bunker first, and I've now set Excelsior up to run slightly better forward.  Please refer to the Ruby sheet for instructions again on how to adjust the reversing valve. 

Putting it all back together again.

Turning the gas off I shot back into the shed and spent the next hour putting all the cosmetics back into place.

Actually, this is a good time to spend some time adding the finishing touches to the body of Excelsior, lining is easier now to,  I'd already lined mine but as the body was off I did take the opportunity to apply several coats of Plastikote varnish, as well as new loco's numbers, the name plate wasn't ready yet!

A word of warning here is not to rush replacing the body work as they may distort.  Especially difficult to refit are the 6 bolts keeping the mounting plate to the running chassis, and the tiny bolts which locate the rear tender to the cab section!  

Before locating the main cab section make sure that the drain down valve pipe work is high enough to allow the body work to slide underneath.  Also check the gaskets for the pressure gauge and all other pipe work.  I found mine were badly cracked and replaced them with some spare thin gasket material I had spare.  If you haven't any, I assume some grease proof paper would be fine.

If you haven't got a set of good quality set of spanners and several sets of nut runners then I'd recommend buying them before trying this modification, or it may well end in tears.


So, how do the new cylinders work?  Do they make a difference?  Are they worth the money?

Mmmm, interesting questions all.  The best way to answer it is with a few before and after notes.  Before I fitted the cylinders I was limited to pulling no more than 3 or 4 plywood wagons with Excelsior, and with the gas on fairly highly, and the safety valve just beginning to lift she would pull them quite happily, with the new SM32 burner the noise was acceptable, without the new burner she would have been howling like a banshee.  Since the new cylinders have been fitted I can pull easily a 8 or 9 wagon train, with a little more than 20 psi on the pressure gauge, with the burner turned down to be nigh on silent.  The only noise you hear is the 'chuff' from the chuff pipe and the slight clickety clack from the rail joiners.

Are they worth the money?  That all depends on how your Excelsior performs with the old cylinders, and what your track is like.  If your line is dead smooth, and you are running light weight wagons then save your pennies to buy something you'll need, as the cylinder conversion is not for you.  At least, not until the 'O' rings fail in the existing cylinders.  If however your line is like mine, with a rise and fall, and you still want to run fairly prototypical length trains of more than 4 wagons then the cylinder conversion is definitely worth it.

The biggest bonus for me however isn't the extra pulling power.  It isn't the longer run either.  It's the control.  Without these cylinders the Excelsior had the same characteristics as a runaway bull on acid.  Two speeds, stop or go.  With the new cylinders fitted you have lost the galloping goose speed, but gained a lot more control on accurate slow running.  For the first time I can say that I have a loco which will work at a scale 5 mph, uphill, downhill, light engine or fully laden.  Now that is something I wanted.

You do need to be aware of the amount of water in the boiler, and 10 squirts now and again doesn't go amiss to keep the water level up.  With the new cylinders and new burner there is a real risk of running out of water before gas, which isn't recommended for a steam engine!

You will find that the cylinders take longer to prime than the old ones, this is just because they're that much larger, and so a few seconds switching from forward to reverse will clear them in no time.

All in all I'd recommend these to anyone with an Excelsior, or anyone of the Accucraft locos which share the same cylinders, the Ida or Ruby amongst them. 

The old Excelsior I always thought of as a challenge, to get the biggest train around the track without the loco stalling, getting the pressure right to limit the noise, the loco wasn't just a loco you could sit down and watch amble round.  With the new cylinders, she is so powerful and controllable that is exactly what you can do.  If you like to sit and watch them trundle round then you'll love the new cylinders, if you like to have to 'drive' the loco, the cylinders will make Excelsior a lot more user friendly, but you'll lose some of her challenge.

All in all though, my faint grumblings must fade to nowt when you compare the loco I have now to the one I had then, I look forward to actually being able to take it to people's garden railways in the summer months knowing she won't let me down, or speed away at the least excuse and cause expensive damage to other peoples rolling stock!

Keith Brown, Chidham Light Railway.