The Unofficial Mamod and Other Steam Forum

CCairns

My eighth live steam loco is this Mamod SL1K.

This was won on ebay a couple of years ago. It came with a water top-up valve, uprated safety valve, ceramic gas burner & replacement steel wheels. Sounded just like the ideal Mamod upgrade, but it was not to be. This ended up being nicknamed the ‘Troublesome Mamod’. It has spent most of its life as what we refer to in aviation as a ‘Xmas tree’, which means it has been robbed for parts to keep other locos running. With the recent purchase of some more Mamod bits, I’ve finally managed to get it running around my test loop of Mamod track.

Wheels - On receipt I found the wheels/pistons were stuck firmly, and ended up breaking one of the crankpins. These are just an 8BA screw, which had a small hole drilled through and used a small spring to keep the coupling rods in place. Of course this turned out to be a weakness of these crankpins and the other one broke soon after. Replacements were fitted, with an 8BA nut being thread locked to keep the coupling rods & washers in the right place. The crankpins are an even smaller fit into the piston rod ends than the standard Mamod ones, and thus there is quite a bit of play. Also the bearings on the driving axle are bigger than the standard Mamod ones (rear axles are the same), and the previous owner had badly enlarged the chassis frame holes, so again there was just too much play.

The steel wheels with the beat up chassis frames.

So I’ve removed these chassis frames & wheels, and fitted replacement chassis frames & Mamod wheels. These wheels came from a box of wheels I got from ebay some time ago, but were loose on the axles. I failed to get them re-punched satisfactorily (Mamod/MSS use a strange punch with 3 splines), and similarly cyanoacrylate glue failed to work on the driving axle. By removing these wheels from the axle completely, cleaning up the axle with sandpaper, and applying torque seal/thread lock to the axle before clamping the wheels back on, this has now produced 2 sets of working wheels, with a 3rd to be similarly treated for a wheel-less SL3 that I’ve won recently. This loco is currently running as a 0-2-2T, as removing those e-clips on the crank pins regularly leads to them popping off inconveniently. Fortunately as it has all been running in the kitchen I’ve managed to find them each time. I’ve not been able to find a source of these e-clips at a reasonable price so far, only as part of a huge box of various sizes in Halfords.

Boiler – This loco was fitted with a PPS ceramic gas burner, which had obviously been running too hot judging by the paint damage on the sidetanks. On the first steaming water was pouring out of the sight glass plastic as pressure was raised. This was due to the plastic being badly melted into the shape of the sight glass boiler cut-out. A new plastic, plus one of the Mamod SP range oval washers was fitted. These washers are much better than the thin ‘O’ ring that is usually supplied. Water was also leaking out of the bottom of the boiler to a varying degree, and a solder repair initially fixed this.

The boiler with the solder repair.

I’ve read on this Forum that some members believe this tube up through the boiler, through which the steam pipe passes, is held on by a rivet at the bottom of the boiler. This is incorrect. The tube has been flared at the bottom end and is just soft soldered to the boiler. Peter Longfils diagram clearly explains this.

Peter Longfils Mamod & MSS Steam Path Diagram.

It seems I did not quite get that soldering sorted out as it still occasionally gets a jet of high pressure water/steam exiting there sometimes, so the boiler has been removed for a full overhaul, and my spare boiler fitted for running trials.

Cylinders/Pistons – These were getting lifted off the back plates due either to a blockage or all that play with the previous wheels. However it appears that the previous owner used some form of torque seal/thread lock and I broke a cylinder pivot bolt trying to fault find. A replacement cylinder was obtained from a former Forum member, but it was still running very sluggish. Trying to fault find the 2nd cylinder ended up breaking its cylinder pivot bolt as well. This time a cylinder obtained from a Forum member was lost in the post due to the packing not being up to the Royal Mail’s gorilla handling. A 2nd set of cylinders obtained from another Forum member had been upgraded to ‘O’ ring pistons, but these require new ‘O’ rings, gaskets and some tidying up to be functional again. I tried fitting one of the pistons from a broken cylinder, but it was too big. Seems that there is a lot of tolerance with these factory produced units. After 2 attempts at sanding down this piston, I’ve finally got a working cylinder unit. Once I’ve obtained replacement ‘O’ rings it is my intention to fit these upgraded ‘O’ pistons together with an IP Eng lubricator which I have waiting in my spare parts box.

Reverser/Regulator – This was full of solder in the cutouts for the steam passage on the lever portion, and even after cleaning most of this out, I still have a misaligned reverser, with more steam available in reverse than in forward. Obviously poorly made with the lever not actually mounted centrally, and when time permits I’ll try repairing this lever portion.

Prior to having the PPS ceramic gas burner fitted (and that has been removed for fitting to my IP Jane [My Live Steam Loco’s No.3] with its silver soldered boiler), it obviously had a Merlin gas burner fitted, as the cab back has 2 holes drilled into it, and there is a large cut-out in the cab roof. These will need to be filled in at some point.

The water top up valve previously fitted to this loco has ended up being stuck under the bodywork of my modified MSS Saddle Tank loco (My Live Steam Loco’s No.4), and the above photo shows it fitted with the water top up valve from another SL1 (My Live Steam Loco’s No.7) which has been borrowed for the trial running. I’ve got another water top-up valve coming from Dream Steam (Mamodevon’s online shop).

My experiences with this loco have proved that not all Mamod locos are good runners, and suffering similar problems with another SL1K which was incomplete & unused when I got it, backs up the theory that I’ve read elsewhere online that the SL1K can be a rogue loco. I think this was due to it being produced during the period of the many Mamod takeovers & new owners.
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Chris Cairns.

http://www.freewebs.com/chriscairnssteam/
http://christophercairns.fotopic.net/

Graham-Jilly · Posted: Mon May 12, 2008 7:22 pm Post subject:

great information Chris thanks for posting

makes great resource material
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CCairns · Posted: Wed May 14, 2008 2:18 pm Post subject:

OK, so the 'O' rings arrived courtesy of Dream Steam (Mamodevon) - Thank you.

As the last cylinder I fitted had a badly leaking rear cover where the piston exits, I decided to just upgrade that cylinder with the 'O' piston, until I get the pipe work sorted out for the IP Eng lubricator.

So after dismantling this cylinder I fitted the 'O' ring piston and used lots of steam oil. However the first attempt at steaming was a disaster as this piston would only move a little in or out but failed to rotate the wheels. So I disassembled this cylinder again, cleaned everything up and this time used lots of light lubricating oil (one of those £1 shop specials). Re-fitted this cylinder and the next steaming was successful.

I am well aware that these 'O' ring pistons take a lot of running in and require a lot of lubrication, having struggled with my IP Jane & a Mamod SL1 which has been upgraded with these 'O' ring pistons. However perhaps they do not like the thick steam oil (I use versions of the 460 oil), at least until it is well heated. Whilst in the real world we have carried the steam oil container on top of the firebox door to keep it hot & thin, what would be the best way to preheat this thick oil in the model world? Could it be heated up in a microwave for example?

Of course once the engine is in steam, the lubricators either on the cab floor or on the smoke box side will get heated up, and thin the oil.

I've started on the pipe work for fitting a former IP Eng lubricator (now Dream Steam), and will post a topic on that once completed.

The other great effect on fitting these 'O' ring pistons is the change to a nice chuff chuff from the exhaust steam, compared to a standard old Mamod or MSS.
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Chris Cairns.

http://www.freewebs.com/chriscairnssteam/
http://christophercairns.fotopic.net/

Johnny E · Newbie Joined: 12 Nov 2007 Posts: 38 Location: Birmingham

I would think that heating up the oil on an electric/gas hob in a suitable container would be a decent replica of how steam oil is heated on big engines. It's horrible stuff when cold and difficult to pump, which is why the some railways keep their barrels on a warming pad 24/7. Hydrostatic lubricators (mostly GWR locos) generally have a warming cock too.

Not sure how the stuff would take to being microwaved though.

Graham-Jilly · Posted: Wed May 14, 2008 7:19 pm Post subject:

quote
The other great effect on fitting these 'O' ring pistons is the change to a nice chuff chuff from the exhaust steam, compared to a standard old Mamod or MSS.

I have to agree Chris

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CCairns · Posted: Wed May 14, 2008 10:08 pm Post subject:

Just fitted the IP Eng lubricator to this loco and it does work.

Like my other IP Eng lubricator, it does not use up all of the oil like a Roundhouse, but there is evidence of oil on the piston rods after cleaning them off between runs.

So I must get on and repair the original boiler for this loco, and fit the second cylinder with an 'O' ring piston.

Interestingly the chuff chuff is now not so noticeable. Wonder if that is to do with the lubrication.

It is great to finally see this loco going around my test loop, as it has been a stalled project for too long.
_________________
Chris Cairns.

http://www.freewebs.com/chriscairnssteam/
http://christophercairns.fotopic.net/