Dead or Alive diesel

Test rig for my last attempt at a 4 stroke live diesel with electric start and 2 to 1 gears.
A testament to Carls unfailing patience.

Looks very impressive David.

Solid enough mountings and the gears appear to be meaty.

Look forward with impatience to the sound and sight of it running. This is a big tease before the 31st eh?

Just one thing. Will those batteries be sufficiently powerful to turn that electric starter motor?
If so what capacity are they?

Good point Carl. The test rig is to test 2 main unknowns. First the gear noise and secondly how to start the 4 stroke without creating so much torgue that the loco leaps of the tracks and distorts the chassis.

In the previous incarnation I used a 12 volt/8AH battery which jumped the motor violently like a defribilator and still would nt turn the IC, albeit with a 1:1 gear ration.

So I have a number of battery options ranging from the 8x1.2 2.8amp set up above up to 12 volt 8amp. I can always add a few more cells. I suppose ideally I would have some device (speed controller ?) that increments the battery power to the tip point for starting. Also experience suggests that a 3:1 ration would be a better link between starter and IC but I cannot achieve this without a third gear train and that requires another mounting and more noise. Also it may be helpful to run the engine in before testing the battery power/gear starting combination but I dont really have that much time at this time of year. Maybe it would be easier with a well run in/worn out IC.

I will have some answers in the next couple of days and presumably you will still be emailable after the 31st ?

Tx again, David

Started fine first time on the 12v8a battery.
Restarted second time and the ic gear unwound off the crankshaft and buckled the 2.5mm brass baseplate. Amazing how much force is generated with the assistance of mechanical advantage from the thread pitch.

Seems that it will work just need to find a way of fixing the gear wheel on a threaded 1/4inch crankshaft. I guess the crankshaft needs drilling slightly to accept and locate the transverse 4mm grub screw hole in the gear rather than relying on friction on the threaded crankshaft surface.

Outside of my competence so I am looking for a local engineering shop.

I guess there must be some adhesive that would fix the thread to the ic shaft even though the thread runs off in the start direction, unfortunately.

...But it started and that's a start.

On the green monster I had this problem and as you say I just drilled into the crankshaft slightly to take the grub screw.
Maybe some Loctite/thread lock might help too.

Could you possibly clamp the gear wheel on the shaft using nuts either side if there is enough thread?

Been wondering whether it will be possible to drill into a hardened threaded crankshaft and whether I might have to grind a flat. Drilling would be better. Did you neeed a special drill as i guess crankshafts are very hardened.

To be honest I didn't make much impression even with a 'pro series' drill bit but I made just enough to 'dimple' a spot on the shaft.

Success at last. Problem resolved by filing a flat in the nice new crankshaft (ouch) and a purchase of Loctite 638.

Starts and runs well but the hardened steel gears make a lot of noise that will require damping somehow. Makes you wonder how electric screwdriver gears are so quiet.

Next step is the soundproofing and a couple of bodies. I thought I might build two small indentically bodied, FEVE type, end cabs. One with the IC gear and the other with a very big lead acid battery and the relays etc. Could run IC in multiple or as a battery single (or double).

Any ideas on soundproofing gears very welcome.

Excellent and that will be running at Railexpo in November......

For the gears I would check the meshing and alignment carefully.
Sounds just like some fine tuning is required.

Troy came up with a simple idea of a threaded rod/bolt as a vertical adjuster. You would have to search his posts somewhere for a pic.

Otherwise some suitable grease might help a little.

Not so sure about sound proofing the body although wood is better than metal but you need to bear in mind cooling.
Anyway I like the noise and the more the better.....°''°

Carl,

will the modified Expo test track still accomodate full size locos or will it be very small and geared locos only ?

It will be able to take the same size stock as before. The radii will be the same for the running tracks.

Carl, do you use any grease on the metal spur/pinion gears on your diesels ?

Test bed now starts first time, runs smoothly and no longer suffers catastrophic failures now that I have 20 M3 bolts holding down the ID/DC down to the base plate.

Noise is a big problem and it sounded like the gears until I tried running the IC from the DC with the glow plug out. Surprisingly the metal gears were pretty quiet so experimentation is now taking place with exhaust design. ie different lengths and diameters of pipe.

Further tests suggest that the noise is from the gears. Maybe the compression stroke tries to slow down the motor and then the combustion speeds it up causing a hammer blow effect on the gear teeth as the gears rattle through the backlash.

Appart from tightening the backlash and running faster I dont think the noise problem will be solvable with a 4 stroke and metal gears.

Glad to hear some progress news. I have much the same gear whine which adds to the symphony!
A blob of grease may help a bit. There are noise reducing greases about that I have never tried.
Silicon grease is thick and seems to be better than others.

Today I ran the test rig a couple of times succesfully. On the third attempt the hardened steel gear on the dc shaft dispensed with a couple of teeth. This appeared (a slomo camera would have been useful) to happen due to some very minor distortion in the dc mount, the 3mm brass base plate or the ic engine moving in its mounting. Of course it could be a bit of all 3.

Clearly the torque forces at work are so great that the engineering requirements exceed my capabilities. An in line coupling certainly has advantages and trying to hold the ic in place with 4 bolts under that kind of stress needs a bit more imagination than I have found so far. Incidentally Carl did you ever test an Oldham coupling. It seems a possibility but has pretty low tolerance to misalignment.

My specification was to produce a remotely startable 4 stroke live diesel. The reality is that I will have to modify the spec to a pull start 2 stroke or obtain the facilities to work in mild steel rather than, presently, in brass and aluminium.

The good news is that my railway which has been flooded for the last few weeks should be operable over next week end, forecast permitting.

Aaaargh David.

I can't remember now whether I tried an Oldham coupling...

I'm taking note of this work because I was going to try and start a 2 stroke aero engine with a brushless motor directly geared.

On the plus side.... it was only the gear that shed a couple of teeth and you did have a couple of successful runs.

Maybe you are not so far away from Jerusalem (I'm reading William Blake at the moment... )

A new gear, more solid mounting and check alignment.....keep the faith!

Carl, I think a 2 stroke/gear/brushless would be fine. My problem is I am limited to a 2 to 1 ratio and therefore need a large motor to start the 4 stroke. This means I am dealing with larger masses, torque and stress. It may be that these values are so high that the gears will strip irrespective of construction quality.

One way out of this vicious circle would be buy a DC with built in gearbox, say about 7 to 1. Drive could be direct with an Oldham coupling or could be with another gear train, but this would be subject to lower stresses than at present.

Last night I had given up for the nth time. Tonight I am looking unsuccessfully for large oldham couplings with small bores and also geared electric motors.

You cant beat a challenge.

see (!!!!!! ) :
https://www.youtube.com/watch?v=ezT5T6ReND0&feature=g-all-u

Thanks very much for that. I have seen this before and very good it is too.

I have also seen Apollo space shots on Youtube but unfortunately I still cant build a rocket.

The main issue as always is connecting the motor shafts. Unfortunately the video does not mention how this arranged. Additionally I would pefer a 4 stroke rather than the Wada 2 stroke.

The much vaunted Wada Works GP9. They also made a Zephyr too.
http://www.flickr.com/photos/scotty_macd/2217697858/in/photostream

All this technology has been emulated and even surpassed by others like Jerry Hyde and Bob Pope.

Wada GP9 spec..

Here a pic of an old Jerry Hyde loco on MLS

MLS Jerry Hyde

I think they both used Oldham type couplings David.

Oldham couplings will take the speed and torque okay but they are not a 'universal joint'.

My original diesel has a brass solid sleeve coupling. Do you want me to get that out and take some pics?
With that solid coupling I allowed the electric motor to float a little allowing for some small inaccuracies in the shafts alignments.

It wasn't very scientific but it worked.

David Grantham wrote:

I have also seen Apollo space shots on Youtube but unfortunately I still cant build a rocket.

Yes...we don't all have the access to machine equipment and the skill to use it.
But funny you should make this comment as recently I showed my live diesel to some engineers at Snecma (who make the engines for Ariane space program) as part of their English course and intriguingly they reckon they could build a simple cryogenic rocket motor powered locomotive in this scale.....

They said they could probably use a small 'thruster motor' that is used for positioning satellites. They even said a plasma engine might work too....

...and I've been telling people all along that building a live diesel is not 'rocket science'...

Thanks for those details.

I am presently testing a large oldham coupling that ought to cope with any misalignment at 3000 rpm. I didn't realise that there was a whole industry dedicated to shaft alignment.

Probably explains why rockets don't have propellers.

David,
would you like a picture or two of my adjustable setup?
I have a bearing fitted on the shaft fitted to a 4mm thread.This allows me to adjust the gear mesh,something I found very useful.

Sparkeswood, thank you for your kind offer, that would be most helpful.