The New??? Mamod Locomotive Mark II

mikewakefielduk@btinterne · Post by **mikewakefielduk@btinterne** » Mon Jan 21, 2013 1:42 pm

Er no, not exactly. The holes in the upright posts are the normal size while the holes in the roof itself have been elongated to the side.

Don't know why but the result is daylight showing round the edge of some of the rivet heads. I'm going to drill them out to a larger size and replace the rivets with nuts and bolts so I can easily get the roof off if needed.

Mike

Aizoon · Post by **Aizoon** » Wed Oct 02, 2013 4:28 pm

My articles are in Garden Rails 198 and 203.

In return, does anyone know how to dismantle the New Mamod cylinders? I think mine are leaking

mikewakefielduk@btinterne · Post by **mikewakefielduk@btinterne** » Wed Oct 02, 2013 8:46 pm

Where do you think you have a steam leak?

I can't say I've ever had a need to dismantle a piston on the Mk11 but they look as though its just a case of unscrewing the front of the cylinder. A 2BA spanner should fit.

Mike

Chris Cairns · Post by **Chris Cairns** » Thu Oct 03, 2013 12:19 am

John,

Where are your cylinders leaking? If it is from the piston rod gland then I have a solution that worked for me.

Mamod did not get the dimensions right for the glands fitted to the Mark I/II/Diamond Jubilee, William II & Brunel locomotives. So when they are cold the 'O' ring inside the gland is not getting compressed at all. Whilst some owners seem to get away with covering the piston rod in 460 steam oil on my William II & Brunel locomotives I fitted a second 'O' ring and do up the gland nut finger tight to get the proper seal (may need slight adjustment to get the best running). As I could not get the big end off of the piston rods I just cut the 'O' ring with a sharp knife and put it on top of the other 'O' which is the one that will get compressed and seal the piston rod.

If your leak is elsewhere then AKAIK those gland fittings are pressed into the cylinder so very difficult to remove.

If you still have problems then best contact with Mamod is by telephone, 0121 500 6433 and ask to speak to Peter Johnston.

Chris Cairns.

Aizoon · Post by **Aizoon** » Thu Oct 03, 2013 10:47 am

No, Chris, what I mean is that the steam is passing through the cylinder into the exhaust even with the loco and pistons stationary. I can see how to undo the cylinder cap but I'm baffled as to how to remove the piston to check the head.

Chris Cairns · Post by **Chris Cairns** » Thu Oct 03, 2013 12:18 pm

That is not good John, sounds like your pistons are worn down enough to allow steam to pass by them. As far as I know the pistons are not fitted with 'O' rings (after all there is no lubricator on the Mamod Train/Mark I), just the 'O' ring for the piston rod gland.

Only method I've seen to remove these pressed in cylinder gland ends requires drilling a hole in the other end then using a drift to push the piston and force the gland end out. In this Topic scroll down to the 10th entry (by syrtismajor) and play his Part Two and Three photobucket video to see what he did to an early William cylinder - http://modelsteam.myfreeforum.org/Upgra ... 16025.html

As I posted above it would be best to talk with Peter Johnston at Mamod as you cannot get their cylinders from any other dealers that I'm aware of.

Chris Cairns.

Aizoon · Post by **Aizoon** » Thu Oct 03, 2013 12:51 pm

Tried that, Chris, but the bl00dy videos don't play on my PC

Chris Cairns · Post by **Chris Cairns** » Thu Oct 03, 2013 1:01 pm

Ah the old computer incompatibility problem with on-line video formats - Apple computer by any chance?

Give me some time and I'll try to screen capture that video and see if I can convert it into a format that you can use - which format would work for you - avi, wmv or mp4, etc? I'll then send it in a e-mail to you.

Chris Cairns.

Aizoon · Post by **Aizoon** » Thu Oct 03, 2013 1:07 pm

Simple bog-standard PC. I can handle pretty well all video formats, Chris. I'd be grateful if you could dig out the videos, though. MPEG?

Big Al · Post by **Big Al** » Thu Oct 03, 2013 3:26 pm

I can't play them either are they still on the other site?

Chris Cairns · Post by **Chris Cairns** » Thu Oct 03, 2013 3:57 pm

It is a problem with the format that Photobucket use to display their video files. I know from that other Forum that many members there complain about being unable to see Photobucket videos and asking the uploader to put them up on YouTube, etc. Apple computers seem to have the biggest problem.

I can still view those photobucket videos OK (using MS Vista plus lots of codecs).

Chris Cairns.

Aizoon · Post by **Aizoon** » Thu Oct 03, 2013 6:01 pm

I finally managed to disassemble a New Mamod cylinder

First we have Naming of Parts - feel free to use the correct terminology

A Cylinder block

B Piston head with gland

C Extra bit that looks like it's turned from the cylinder block but is in fact a force fit

D Piston rod gland

E Cylinder cap

F Piston rod

G Big end

Most of this disassembly is fairly obvious except for C, henceforth known as the Extra Bit, or EB. The trick is to hold the cylinder in a vice (with padding) and over-tighten the cylinder cap (E) with a spanner until the EB turns in the cylinder and can be wrenched out with pliers. The cylinder cap can be removed from the EB by clamping the EB in the vice and using the spanner in reverse to loosen it. No teeth were removed in this process.

Even a moderate pull seems to remove the Piston Rod (F) from the piston head (D), but it seems to click back OK.

Now we can remove the Piston Head (B) from the cylinder (A). "How?", you ask. This is the clever bit. Fill a syringe with water, squirt it into to the forward port of the cylinder, and the head pops out. Neat, eh?

My problem, incidentally, seems to have been a bent piston rod (much more bent than (F) in the picture). Perhaps a stainless steel replacement would be in order?

The O-ring on the piston head looked fairly inadequate, too. It had a slightly smaller external diameter than the head into which it fitted, which surely can't be right.

Aizoon · Post by **Aizoon** » Thu Oct 03, 2013 6:26 pm

Totally as a beside, storing your videos on Dropbox lets you use a standard video format like MPEG without it being fiddled with. Much better than PhotoBox and the like

SapperAnt · Post by **SapperAnt** » Thu Oct 03, 2013 6:39 pm

Thats what I do but can be very slow to load....

Chris Cairns · Post by **Chris Cairns** » Thu Oct 03, 2013 8:31 pm

But at 2GB for the free account it gets filled up quickly.

Had a fellow railtour colleague send me some hires photos. Second batch overwrote the first batch before I'd copied them and I've no free space until I copy or delete the second batch.

Chris Cairns.

Chris Cairns · Post by **Chris Cairns** » Thu Oct 03, 2013 8:43 pm

John,

Thank You for posting the photo of a dismantled current Mamod oscillating cylinder.

So what were Mamod thinking of by using 'O' ring pistons without a proper lubricator on the Mamod Train/Mark I locomotive? Glad I managed to fit a dead leg lubricator to mine.

Chris Cairns.

Aizoon · Post by **Aizoon** » Thu Oct 03, 2013 8:44 pm

I pay for lots and lots of space and use it for backups. Well worth it, IMHO.

Aizoon · Post by **Aizoon** » Thu Oct 03, 2013 10:08 pm

Chris Cairns:90083 wrote:John,

Thank You for posting the photo of a dismantled current Mamod oscillating cylinder.

So what were Mamod thinking of by using 'O' ring pistons without a proper lubricator on the Mamod Train/Mark I locomotive? Glad I managed to fit a dead leg lubricator to mine.

Chris Cairns.

Not to mention using a brass piston rod. I wonder what the other one will look like when I dismantle it?

Aizoon · Post by **Aizoon** » Fri Oct 04, 2013 3:02 pm

Aizoon:90088 wrote:
Not to mention using a brass piston rod. I wonder what the other one will look like when I dismantle it?

Much the same, really.

I've replaced the O-ring on one cylinder and the improvement is dramatic, at least when testing the cylinder alone. Can I just ask what type of O-ring I need? I only had one in stock and need to replace the other.

Chris Cairns · Post by **Chris Cairns** » Fri Oct 04, 2013 4:15 pm

John,

As you are the first owner to successfully take apart a new style Mamod oscillating cylinder that I'm aware of then I do not think anyone here will be able to provide you with the correct 'O' size.

From the updates that Mike Wakefield posted regarding the stalled Thomas Telford project Mamod use nitrile 'O' rings. From research on-line and a recommendation from another live steam Club I've found that using viton 'O' rings instead should give better results.

A phone call to Peter Johnston at Mamod should get you the right size, and if he has any in stock I'm sure Peter would post you a couple.

If you do get the correct size posting that information here would be very useful for future reference.

Chris Cairns.

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The New??? Mamod Locomotive Mark II

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