Telford Tales

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Telford Tales

SLR
Junior Member
Joined: 11 Jul 2014, 18:31

04 Sep 2017, 21:15 #1

I thought it would be a good idea to start a thread for Mamod Telford owners, so that experiences can be shared and problems highlighted. Also possible solutions can be discussed, as well as ideas for improvements and general modifications.

There are a number of threads on the forum relating to this particular engine already, some of which contain useful tips and advice. Here are the ones I could find, going back as far as 2014:

http://modelsteam.myfreeforum.org/about78151.html

http://modelsteam.myfreeforum.org/Mamod ... 81545.html

http://modelsteam.myfreeforum.org/about87833.html

http://modelsteam.myfreeforum.org/about89498.html

http://modelsteam.myfreeforum.org/about90772.html

http://modelsteam.myfreeforum.org/about96847.html


And of course, forum member Coldgunner's (oft-hijacked and derailed :D ) epic thread:
http://modelsteam.myfreeforum.org/about91095.html

Sadly many images are no longer viewable due to photobucket's change of policy.
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SLR
Junior Member
Joined: 11 Jul 2014, 18:31

11 Sep 2017, 12:59 #2

So, as I mentioned on another thread, my Telford had developed a knocking noise when running under load. This turned out to be due to wear in the connecting rods, at the "big end". This was somewhat surprising, as the engine is only two years old and hasn't really had that much use.

Worn big ends:
Telford big end 1.jpg  
Drilled out, also showing the original spacer that goes onto the crankpin, between the con rod and coupling rod:
Telford big end 2.jpg
My solution was to make some new shouldered spacers, which were then silver soldered to the con rods:
Telford big end 3.jpg As can be seen, this has greatly increased the bearing area, so should hopefully not wear as fast.

After this work was completed, I gave the engine a quick run, and tried to make a little video. Unfortunately, by this time it was a bit dark outside and apparently £40 video cameras aren't good in low-light situations! Here it is anyway; you can just see me legging it to get a torch at around 20sec. At the end, the torch runs out of battery moments before the engine stops, having run out of gas.  The engine was pulling 13 assorted Mamod wagons, weighing around 5kg total.

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Mamod
Junior Member
Joined: 02 Jul 2009, 11:26

13 Sep 2017, 20:48 #3

Early con rods were steel we now use stainless 
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SLR
Junior Member
Joined: 11 Jul 2014, 18:31

13 Sep 2017, 21:46 #4

Mamod wrote: Early con rods were steel we now use stainless 
The con rods and coupling rods on this engine are stainless steel, the eccentric rods are steel. Maybe a more wear-resistant grade of stainless would be an idea? They could also be a bit thicker, and a slightly larger diameter crankpin would help too; 3mm does seem a bit small.
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mikewakefielduk
Junior Member
Joined: 23 Apr 2015, 17:32

14 Sep 2017, 09:40 #5

 Am really having issues with this new Tapatalk forum. Keep getting an Error 502 Bad Gateway when I post something and then end up with either an empty posting or everything duplicated. Grrrr. So let's try again.....

Anyway, good idea SLR to start a new thread on the Telford as the previous ones were getting unwieldy.

My Telford, although older than yours and having done quite a lit of running, still has con rods with circular holes. As discussed elsewhere, its knocking noise was cured after fitting a new wheelset and piston valve block. I'm taking the loco to a steam-up this coming Sunday, along with the Brunel, and plan to video its running assuming it isn't raining (my camera isn't waterproof). I'll post the outcome here.
Last edited by mikewakefielduk on 14 Sep 2017, 10:11, edited 2 times in total.
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gen3v8
Full member
Joined: 13 Aug 2014, 11:32

14 Sep 2017, 10:00 #6

Good result SLR
Dave

Aeterna Non Caduca 🇦🇺
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SLR
Junior Member
Joined: 11 Jul 2014, 18:31

16 Sep 2017, 12:14 #7

Thanks for the replies, guys!

I have decided that it is time to do something about the Telford's poor combustion chamber design, and dismantling the engine revealed a lot of oil:
Mamod Telford combustion chamber1.jpg In this picture you can also see the experimental burner that I made to replace the original ceramic one which became damaged by oil contamination. The only problem I encountered with this burner was that it was more affected by the wind and easily blown out, which I will have to take into consideration when designing the new combustion chamber.

More oil..
Mamod Telford combustion chamber3.jpg
And more...
Mamod Telford steam pipe1.jpg Even though I wipe the engine down each time after it's been used, there is no way to clean off the oil that sits between the various plates. This is also something that I need to deal with, so will be making some sort of condensate trap.

Another thing I thought I'd change is the way the steam pipe connects to the distribution block at the front of the engine, as other owners have identified this as a possible point of failure. 

Mamod Telford steam pipe2.jpg As you can see, I've cut the tags on the frames that previously formed a rudimentary smokebox saddle level with the top of the footplate. I have then turned the distribution  block around and blanked off the original steam pipe connection. To give room for the new banjo connection, I cut out the section of footplate around the exhaust clearance hole, between the two existing slots.

Hopefully I'll be able to make some more progress today.
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mikewakefielduk
Junior Member
Joined: 23 Apr 2015, 17:32

16 Sep 2017, 15:45 #8

Blimey, that's an awful lot of used steam oil on the various plates and also on the inside of the heat shields. My Telford's old heat shields (taken off a few weeks ago when I replaced them with ones without air holes) look nothing like yours. It might be worth investigating why you're using so much oil.

Also, while you're in the process of remaking bits, how about adapting the distribution block to be like the latest design from Mamod? It has twin side-by-side exhaust pipes (one from each cylinder), each about an inch long and then crimped shut with a hole drilled in the front to create a bit of exhaust back pressure. I'm sure I had a photo somewhere but can't find it. If I do I'll post it here.
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mikewakefielduk
Junior Member
Joined: 23 Apr 2015, 17:32

17 Sep 2017, 20:42 #9

Today I took my two Mamods to a steam-up in a beautiful location next to the Montgomery canal.  The track wasn't perfectly flat and had tight curves, a bit like my own garden line. I was able to run the Telford. It ran really well and attracted some favourable comments. What a difference a new wheel set and piston valves make.

 Unfortunately the Brunel was too tall to run because of the small tunnel mouths, a problem which also meant other locos either couldn't be run either or had to have bits of their cab removed.

ImageImage
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SLR
Junior Member
Joined: 11 Jul 2014, 18:31

18 Sep 2017, 22:45 #10

mikewakefielduk wrote: Blimey, that's an awful lot of used steam oil on the various plates and also on the inside of the heat shields. My Telford's old heat shields (taken off a few weeks ago when I replaced them with ones without air holes) look nothing like yours. It might be worth investigating why you're using so much oil.

Also, while you're in the process of remaking bits, how about adapting the distribution block to be like the latest design from Mamod? It has twin side-by-side exhaust pipes (one from each cylinder), each about an inch long and then crimped shut with a hole drilled in the front to create a bit of exhaust back pressure. I'm sure I had a photo somewhere but can't find it. If I do I'll post it here.
Yes, this engine drinks more oil than an old Alfa Romeo! Actually, I get 3 - 4 boiler fills to one filling of the lubricator, which I thought was OK; how much does yours use?

I know what you mean about the new exhaust arrangement, but it won't help with the condensate issue. Here's what I've done so far:
DSC00209.JPG I made a little chamber from an off-cut of square brass tube, which was then soft-soldered to the distribution block. You can also see that I've drilled two extra holes in the frames; this is because I have turned the valve blocks around so that the exhaust port is now at the bottom. Two corresponding holes have also been drilled in the distribution block to allow the exhaust to pass into the chamber.

DSC00210.JPG The exhaust steam then exits through a new hole drilled in the distribution block (just visible in the first picture above) which connects with the existing exhaust pipe.

All assembled, painted and ready to fit. I even made some new gaskets!
DSC00211.JPG
The chassis has been reassembled and tested on air; all seems OK. Next is the combustion chamber. And I've had a few ideas about modifying the bodywork... hopefully I'll be able to get the engine back together enough for a steam test next weekend.
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