Brian's Donkey Engine

[Maryak]

Brian,

Almost without exception these engines were controlled by a throttle and a Differential Valve to reverse the direction of rotation. The engines were also full admission with no lap or lead.

I hope this is what you are looking for.

Best Regards
Bob

 

[steamer]

Wot Bob said.!

The valveing on the tug winch I got into was very similar to what bob has posted...and yes full admission/ full stroke.

Dave

 

[Captain Jerry]

Bob

that is a very interesting valve arrangement but I don't think it has anything to do with the donkey style winch that Brian is building. It appears to be two cylinders in a common block, separated by spool valves and an integrated control valve. That might be what you find in a shipboard winch but on this type of machine, the cylinders are about 4' apart and reversing was not common at all. If reversing was supplied, it used Stephenson or Gooch linkage.

I don't think you can reverse a D-slide valve engine by swapping the inlet and outlet, can you?

Jerry

 

[Brian Rupnow]

Gentlemen---In regards to whether or not a small valve like I built yesterday will serve to adequately control my twin cylinder donkey engine.--Please look at the attached vido.

 

[steamer]

Hi Brian,

I don't have any issue with a ball valve as a throttle...I use one on my steam launch! Works very well there.

Steam winches typically had full cut off.....that was my point

Whether a donkey had full cut off or not....well....guess I can't really say.

Glad it's working out for you!

Dave

 

[Brian Rupnow]

Just ordered up all my fittings and 3 foot of pipe from PM Research. I found a post on here the other day about making up jigs to machine the cast brass fittings. Now I'm going to have to hunt it up again!!!

 

[Captain Jerry]

Good show! I never had a doubt.

Jerry

 

[Harold Lee]

Hi Brian,

I don't have any issue with a ball valve as a throttle...I use one on my steam launch! Works very well there.

Steam winches typically had full cut off.....that was my point

Whether a donkey had full cut off or not....well....guess I can't really say.

Glad it's working out for you!

Dave

Come on Dave.... After the teaser of the backhead of your boiler, show us some more of it!!!

Harold

 

[Maryak]

I don't think you can reverse a D-slide valve engine by swapping the inlet and outlet, can you?

Jerry

Whilst not common, in full size practice, actually yes. Of course the valve needs support on the back face or the steam pressure would simply blow it off the valve face and connect all ports. This was overcome by using a balanced valve called an Andrews and Cameron valve.

Best Regards
Bob

 

[steamer]

Harold,

Do a search under "Rushforth" and you'll find it....don't want to hijack Brians thread.

Dave

 

[Brian Rupnow]

This is probably where I am going to go next on this build. The engines are finished, and the boiler is finished except for cosmetic fire door and ash clean out doors. My piping is on order from PM Research, and there isn't much else that I can do for the present. I have no idea at this time just how I am going to attach the gear to the shaft, but it may end up being a cross pinned solution. I can't make the hub any larger, due to clutch considerations, which means I don't have sufficient room for a key and set screw.

 

[Brian Rupnow]

Today I spent some time working on the large winch gear. When I bought the brass for this project, all my supplier had was 5" diameter. Not wanting to wait untill he ordered in another 12 foot stick of 4" diameter, I paid an exorbitant price for the 5" and had him part off one piece 1" long for the winch gear. I absolutely hate using my 4 jaw chuck, but need must when the devil drives and here you see a picture of what I was about today. I pared off the perimeter with my bandsaw, as I didn't want to turn it all into chips. Then I set the rather ungainly piece left up in my 4 jaw and turned the o.d. to 3.833: which is the o.d. of the 90 tooth 24dp gear I will cut, and then drilled, bored, and reamed the center hole all in the same set up.

 

[Brian Rupnow]

And here are the "parings" which I will save and use for little brass parts. Somehow my photo software has managed to turn this picture all cock-a-hoop, but you get the idea. This brass is too outrageously expensive to throw any usable bits away!!!

 

[Brian Rupnow]

There is my 'orrible, daggerous trepanning tool at work. Its a parting off tool ground to a long wicked point, and it seems to work perfect for trepanning. I take a series of 0.100" plunge cuts across the front face of what I am trepanning at about 250RPM, then a couple of .005 deep cuts all the way across at 1500 to smooth the ridges out. It works better than any other way I have tried to do this. The long 5/8" rod held in the tailstock chuck is not actually touching the part. Its about 0.040" clear of the part. I have had parts suddenly jump out of the chuck jaws while doing this type of operation and scare the Bejesus outa me, so I put that rod in as a "safety anti-jumper outer". I have yet to decide if I will leave that bit of remaining hub in and take it out in a later operation, or take it out now.---Brian

 

[Brian Rupnow]

Now I've put the 3 jaw back on and flipped the part around to machine the other side. I have intentionally left the 0.625" hub longer than necessary.

 

[Brian Rupnow]

Now here is a little mystery that I have never completely figured out, but I know from experience it is so. In my first set up, in the four jaw chuck, I turned the outer diameter of the part and drilled/bored/reamed the center hole all in the same set up.---Should be concentric, shouldn't it. However, when I mount the part on a snug fitting arbor and put it back in the 3 jaw, if I put a dial indicator on the outer diameter of the part, then rotate it, I get about .003 to .005 "run-out" condition. I assume that is an indication of the run-out in my 3 jaw chuck. I am going to "pin" that extra bit of hub on the trepanned side to the shaft, then when I move over to the 3 jaw in my rotary table I will grip he shaft, not the actual brass part which really doesn't have sufficient hub to hang onto. Remember that I need clearance for the gear cutter between the brass part and the actual chuck jaws.

 

[Brian Rupnow]

We have a 90 tooth gear!!! And the hub which was purposely left on the "wrong" side is now gone.

 

[AussieJimG]

"There is my 'orrible, daggerous trepanning tool at work."

You have set me wondering Brian. If you were considering removing the remaining bit of hub anyway, why did you not just use a boring bar? That is what I was planning for a flywheel that I am about to make and now you have me worried. What am I missing?

Jim

 

[Brian Rupnow]

I probably could have used a boring bar, but its a 3.1" diameter hole. thats more cranking than I want to deal with, but it probably works out the same.---Brian

 

[AussieJimG]

Thanks Brian, I thought I might have been about to make one of those mistakes that one has to post on HMEM with photos. You have set my mind at rest.

Jim