Another Mamod "Thing"

[Chris Cairns]

Some time ago a fellow Forum member asked me for more details of the Mamod "Thing" that is currently my avatar. So I thought an illustrated Topic would provide the answer, and be useful to share with other Forum members.

I have a few spare Mamod/MSS flat bed wagons and I've always wanted to build a Mamod "Thing" out of one of these. However the preferred engine, a Mamod MM1, always seemed to go for good prices on evilbay, and of course there was also the decision on how the MM1 would provide the drive to the wheels.

So when this Mamod "Thing" appeared I decided to bid on it for a fair price considering all the components used.



It is not the only Mamod "Thing" I've placed bids on but this was a successful bidding. It uses 2 spring drive belts via flywheels & pulleys to transfer the drive to the forward axle.



As you can see as a meths burner it is in a dirty state as the vapouriser burner used is really too small and without modification is somewhat of a fireball (hence the deflector plates fitted to the firebox.

So I have decided to strip down this "Thing", clean it up and identify all the components used. It started off as a Mamod lumber wagon (these are the most common chassis's on eBay as the logs get lost - I would recommend using a flat bed wagon instead for the full length floor). The original coupling rings have been replaced with crude bent pieces of wire, and the coupling hook on the top of the coupling mounting has been removed and replaced with another piece of wire bent as a hook (like the centre buffer coupling hooks).



So a rivet from one side of the chassis frame has been removed (to allow the spring drive belt to be fitted) and the rivet holding one drag beam has also been removed (not sure why but it probably was no longer holding the drag beam to the chassis floor). The two red lugs mounted at the rear of the chassis frames have been removed so their mounting holes can be used for the intermediate drive shaft fittings. The front axle has a brass Mamod 1/2" pulley fitted for the final drive, and the rear axle has a yellow plastic 1/2" pulley Meccano Part No.23. This may have been to provide 4WD on both axles so I have obtained another plastic pulley to fit on the front axle.



The intermediate drive assembly is made up from a yellow flanged plate Meccano Part No.51, two yellow flat trunnions Meccano Part No.126A, and two fishplates Meccano Part No.10 (used to hold the flanged plate onto the chassis through those holes where the red lugs were fitted). It has a 3 & 1/8" axle Meccano Part No.16 (trimmed) with a brass Mamod 3/4" pulley & a Mamod 1 & 7/8" 4 holed flywheel (as fitted to their line shaft).

More to follow shortly after I clean it all up, and reassemble it.

Chris Cairns.

[The Denying Dutchman]

The burner too small? I own an older MM1 with a wick burner which already runs like a bat out of hell!

[Chris Cairns]

I do not have a one wick meths burner for comparision but I'm sure the tank capacity is greater in them than the small vapouriser burner that replaced them. If you fill the vapouriser burner full up (approx 10mls) when the burner heats up the vapour comes out all the edges catching fire spectacularly. So I've modified mine to try and reduce the vapour leaks. It gives about 8 minutes running time maximum on the track.

The meths runs out well before the water in this MM1 despite the fact the water level plug has been mounted too low down on the end plate.

Yes the MM1's are known for high speed running but the drive belt system on this "Thing" brings the final drive down to a manageable level (will need to wait until it if fully reassembled to roughly work out the speed reduction).

Chris Cairns.

[The Denying Dutchman]

I though you meant that the heating surface of the burner was too small.

I have no clue how longer the wick burner burns, but it's obvious that the performance of the engine is much less than with the vaporising burner.

[DLRdan]

I buuilt one of these a while ago, it ran very well. I copied the tank size and wick tube of the original burner, on the single wick with aroun 12ml it burnt for just under 30 minutes and run times with hot water to start were around 25.

[Chris Cairns]

25 minutes running is impressive so I'm assuming that was not on a water level plug fitted MM1.

The problem with the vapouriser burner is it has a larger burning area than the 1 wick burner tube so the meths gets used up much quicker. Forest Classics sell an adjustable vapouriser burner but this "Thing" does not get run enough to justify spending another £14.

Chris Cairns.

[DLRdan]

Took a while but managed to find the video of it


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[Chris Cairns]

A'ha,

Would that be this one which was on eBay some time ago Dan?



Chris Cairns.

[DLRdan]

Thats the one

[Crackingjob]

It was me that asked Chris and thanks for the photos, it makes sense now

Looking at the one built by the late Peter Jones, he felt that he should have used chain and not the stretch belts...do you find them stretching?

Crackingjob

[Chris Cairns]

do you find them stretching?

Dave, that is the problem with the Mamod spring drive belts if they are left in position under tension. If you look at the 2nd photo I posted above (one of the eBay photos which I used to make my avatar) you can see the drive belt from the engine to the intermediate drive shaft is badly stretched, and indeed broke just after I started running this "Thing". It is one of the standard Mamod drive belt sizes so easily replaced. I've read that the Wilesco drive Belts are better for not stretching as badly but have no real experience of them. I guess the problem with a chain drive is where you fit the sprocket on the wheel axle as there is not much space outboard of the wheels on the 32mm axles for a meccano chain.

It is interesting to see how Dan cut down the firebox for his burner to be more efficient. Mine has the standard firebox plus a lot of open space in the floor which obviously soaks up a lot of the heat output. If you have not seen it here is another MM1 tram build which went through a few changes, including a cut down firebox - http://modelsteam.myfreeforum.org/ftopic246-0-asc-0.php

So here is the re-assembled chassis and intermediate drive shaft.





The burner is rather crudely held in place by a friction fit using 2 x 4 & 1/2" perforated strips Meccano Part No.2A with screws, nuts and washers as posts.





These vapourising burners suffer from a small tank capacity and as they have no separate vent the hot vapour tends to leak out under the top slide at the sides and catch fire. That is why this "Thing"'s firebox has extra brass sheet deflectors fitted. I have sealed up most of these edge leaks by scrapping the paint off around the tank edges, lots of flux then carefully applying solder with an electric soldering iron.



More to come as I'm still cleaning up the thick meths residue off the firebox & boiler.

Chris Cairns.

[Chris Cairns]

And so to finish off the reconstruction of this "Thing".

As I posted above using the flat bed wagon would provide a full floor panel making the mounting of the components, including the boiler/firebox easier. So on this lumber wagon chassis the boiler/firebox is mounted using two yellow flat trunnions Meccano Part No.126A.



These are mounted underneath the crossed frame floor over the front axle. As you can see above earlier in this Topic the strap mounting the boiler was reversed and placed over the firebox. Not sure why this was done but I've returned it to the original orientation so will see if that causes any problems whilst running.



Previously I've read comments from some others on-line boasting the superior quality of the earlier Malin's built Mamod products over the current produced models. However the MM1 was introduced as the budget stationery engine and from those videos I've viewed on-line plus my experience of this 1975 Water Level Plug MM1 I can now understand why they vibrate so much.



Whilst it is not the best camera lens angle to show the problem hopefully you can see that the cylinder/engine frame have not been mounted at 90 degrees to the flywheel crank shaft. it would require the engine frame to be straightened and a longer piece of pipe used from the boiler to the engine frame. The flywheel is also a fair bit out on the crank such that there is a lot of free play sideways, but that is probably because the flywheel has been pulled sideways whilst driving something.

This particular MM1 has also been modified with the addition of an exhaust pipe to the chimney. Helps keep the condensate away from the vapouriser burner.

Anyone else like to share their Mamod "Thing" with our community?

Chris Cairns.

[Chris Cairns]

Having put the "Thing" back together I thought I'd give it a run to make sure it was OK, and take some timings, etc. prior to it going back into storage.

Kitchen temperature 19°C. Filled the boiler with 60mls (approx. 75% boiler capacity) of kettle boiled water. Filled the vapouriser burner to the brim. Took 02:35 mins to raise working steam pressure. Removed the burner to refill it but as it was hot now it suffered from that vapour leak problem again. Finally got it working OK after a good wipe down.

Ran for 10:20 mins completing just under 50 laps of my standard Mamod loop, and removing a drive belt it ran for another 0:20 secs. Boiler had 25mls water left.

So a more efficient burner would produce a much longer run.

Oh and that run raised my kitchen temperature by another 1.5°C - could meths be a cheaper central heating option with the approaching gas & electricity price hikes!?!

Chris Cairns.

[pauly]

Iv been gathering bits to make a Minor Thing, got all the sprockets, chain and a tatty MM1 all I need is a mamod flat wagon and Ill be good to start