Garden Railway Forum

Dear All,

I'm a 45 mm gauge man. I've moved up from 16mm scale. My first foray into a larger scale was my 24 mm scale George Henry DeWinton. Now I've decided to go the whole hog and switch to 12th scale. I had thought about resurrecting Gauge 2 (2 inch gauge), but I don't mind being a little under gauge, at least it will look narrow gauge.

A couple of years ago I bought an O.S four stroke model car engine via eBay. I've just fired it up in my test chassis. I'm running-in the the engine on a super rich setting, the garden was engulfed in the lovely castor oil smoke. My current project is making a muffler for the exhaust, at present it's just a straight through pipe, and is too noisy.

My plans are based on Dave Watkins' "Detritus". The chassis has no clutch at present, and only forward gear, it's being used to trial the required gear ratio. The primary reduction is via worm and wheel, then a spur gear reduction.
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Best wishes,
Dave

Good looking beast so far, keep us posted please on progress

Now that's what I call engineering  :D

I'm assuming that is a car spec OS 20 or 26 Four Stroke?

I have only ever seen one of those on ebay with a pull start in the last couple of years and it went too high for my budget!

I'm very temped to make a radio controlled diesel-electric but on a BO-BO chassis probably based on Vale of FFestiniog (yes I know V-O-F is a diesel-hydraulic!). I have a vague plan for the engine throttle to control itself based on the electrical load the traction motors are experiencing.

Do you have any issues with vibration?

Stuvon:80459 wrote:I'm assuming that is a car spec OS 20 or 26 Four Stroke?

That's right.

Do you have any issues with vibration?

It certainlly vibrates enough No fastener has come loose yet.

Best wishes,
David.

Here's a couple of videos. The first showing the very first starting of the engine. This video ended in catastrophe as the rear universal coupling broke as I blipped the throttle. They both have covers on them now so they can't break-out.



The second video is of the first run on the line. I recorded speeds of 7.5 & 9.5 scale MPH. I try to run slowly.



Best wishes,
Dave.

Most impressive, very nice slow running.

It is better to have the worm gear reduction in the final stage of the reduction gearing. It will wear rapidly in its current position.

Looks fantastic so far!

Adding a clutch should be fairly easy, although setting it to engage at the correct RPM could be fun.

How are you going to change direction?

Busted Bricks:80536 wrote:It is better to have the worm gear reduction in the final stage of the reduction gearing. It will wear rapidly in its current position.

Hmmm, we'll have to see. But, this is a test chassis, built to test the required gear ratio. I may omit the worm gear reduction in the end and switch to all spur gear plus bevel gears. Ideally the transmission should be under footplate height, or perhaps with a narrower central tunnel for the driver to straddle.

Stuvon:80537 wrote:Looks fantastic so far!

Adding a clutch should be fairly easy, although setting it to engage at the correct RPM could be fun.

How are you going to change direction?

Thank you. I'll go for a manual clutch, operating from a lever. Gearing will be used for reversing

Best wishes,
Dave.

Hi Dave

First of all ide like to say well done on what you have achieved, that looks pretty impressive, and i am a HUGE fan of what David Watkins has achieved with his detritus locomotive.

I am very interested in this build, as im not sure if you are aware or not, but I am also playing around with live diesel, and I currently have 2 locomotives, and im working on my third. The third loco has an os 4S 40 engine, but unlike yours and Davids, mine are all diesel electric, as opposed to diesel mechanical, as at the moment, that would be pushing my abilities over their limit.

Just in case you havnt seen, heres a video and check out my channel, as you talk about using a clutch, and as youl see, in the later videos, my latest version of the loco has a clutch with gearing.

http://www.youtube.com/watch?v=hwTlJ031pDk

Where abouts are you based?

Keep up the good work.

Anton

Anton Richards:80552 wrote:Hi Dave

I am very interested in this build, as im not sure if you are aware or not, but I am also playing around with live diesel, and I currently have 2 locomotives, and im working on my third. The third loco has an os 4S 40 engine, but unlike yours and Davids, mine are all diesel electric, as opposed to diesel mechanical, as at the moment, that would be pushing my abilities over their limit.

Anton

Thank you Anton. Yes, I've seen your live diesel activity. It has encouraged me get my act together and get started.

I've just updated my location, so it should be displayed now.

Best wishes,
Dave.

It's taken two weeks to make a silencer for the engine. I did a bit of research into automotive silencers. First I had to order a strange metric die to cut a M9 x 0.75 thread to fit the cylinder head.

The outer shell was rolled from 0.5 mm brass sheet and silver soldered, then a central baffle plate was silver soldered in. Then the endplates, and then the bushes, and finally the drain tube.

I've fitted copper tubes over the universal couplings to prevent them from bursting apart again.

Here's a video of yesterdays run with the silencer in place. It works a treat. The drain dribbles the excess oil down onto the ballast. There are pictures of the silencer at the start of the video.



Best wishes,
Dave

I thought I'd try a massive secondary flywheel in a handy empty spot at the rear of the loco. It wasn't a success, it slowed the motor down a bit - needed more throttle, and always came loose. When still clamped securely it didn't improve running much. I've taken it off now. These are the latest photo's.





I had a run yesterday and today. One thing that has changed is the engines compression, it's much higher now. Yesterday I started leaning out the engine to see the difference in running. It certainly smoked less and the throttle needed decreasing to maintain the same speed. But, in the end there was no advantage in running lean, it wouldn't run slower. It's much safer to run rich, but it is safe anyway as I'm using castor oil. The garden smells fantastic...

Best wishes,
Dave.

These two videos show the effectiveness of the new silencer:

First run on the track:


New silencer:


I have bought one of these non-contact IR laser point infrared digital thermometer temp guns from our friends at ebay.  Excellent service, postage free from China.  I want to test the engine temperatures.
Today I had an extended run of the loco and experimented with leaning-out the engine.  Normally the engine is being run at a super rich setting of needle valve open 2 turns.  I leaned-out the engine until the needle valve was only open 1.5 turns.  On the super rich setting the cylinder temperature was about 115 deg C, and fully leaned-out it was about 135 deg C.  The cylinder head temperature was over 150 deg C.

Fully leaned-out there was minimal smoke, which is most unsatisfactory

Best wishes,
Dave.

Interesting to see the running temperatures, and it's nice to get an idea of what to aim for when the loco has body work. when you do eventually get round to encasing the engine you will probably need to consider forced cooling.

The engine was originally designed to be forced cooled by an airplane propeller or in an RC car you generally need to keep moving to prevent overheating.

Stuvon:81572 wrote:when you do eventually get round to encasing the engine you will probably need to consider forced cooling. The engine was originally designed to be forced cooled by an airplane propeller or in an RC car you generally need to keep moving to prevent overheating.

I have been thinking of a fan cooling system. But, with the rich setting required for good smoke effects comes excellent cooling from all that evaporating excess methanol. Plus, castor oil provides fantastic high temperature lubrication.

The black coloured engine helps radiate heat, and the frame absorbs quite a bit of the heat too. The engine is only idling and not making much power.

Best wishes,
David.

From an engineering point of view one should never put a flywheel at the end of a shaft, particularly with a single cylinder engine. you are going to get torsional vibrations at some revs or other.

Worm gears are always less than 50% efficient, typically less than 25%, just saying.

Boustrophedon:84721 wrote:From an engineering point of view one should never put a flywheel at the end of a shaft, particularly with a single cylinder engine. you are going to get torsional vibrations at some revs or other.

Worm gears are always less than 50% efficient, typically less than 25%, just saying.

Thank you for that.

In practice the large flywheel had little desired effect and wouldn't stay attached to the shaft; when the engine was stopped it would be spinning freely for quite a while.

Gear efficiency is not an issue with the loco really, it is far too powerful as it is.

Anyway, the gearing as you see it was to determine the required ratio. I've recently been busy cutting Mod 1 spur gears, an enjoyable and slow process.

Best wishes,
David.

I have been working quietly behind the scenes for months. We now have a primary gearbox fitted with a 4-stage spur gear reduction. The gears are quite massive and the whole box weighs quite a bit. Here's a short video of me powering-up the box using the lathe.



Best wishes,
Dave.

On Sunday we had a fine outdoor test of the new clutch and gearbox.





I've been green and plumbed the excess engine oil from the muffler into the gearbox. The gearbox covers are to stop oil-spray and dirt getting in, and are not air-tight. Along with the oil, a fair amount of exhaust is also being pumped into the gearbox and wafts out of all the gaps. At the end of the run, there was a lot of oil in the gearbox, Klotz Benol castor oil.

This was the first run since March. The torque output is fantastic even with the clutch partially engaged. In the video you can see me putting some resistance on the output pins, it doesn't stop the drive even when not fully engaged. The drive is very smooth, I'm expecting some smooth starts when the loco has a final drive...

Best wishes,

Dave.