Vertical hit and miss engine

[Brian Rupnow]

I'm still thinking about a mechanism which would automatically give a variable load to the hit and miss engine. The idea of an offset weight mounted on the end of a rotating arm is great, except for one thing. When lifting the weight against the pull of gravity, the engine would be forced to actually "work". However, once the weight went "over center" and began to drop, that force would feed back thru to the engine, which is what I want to avoid. I could use a one way clutch bearing so the drive wouldn't feed back to the engine while the weight was swinging down under the force of gravity, but there is no way to predict when it will stop swinging. A few years ago I was messing around with worm gears. I had read about making your own model sized worm gears, and wanted to try it for myself. I was impressed by how well it worked, and created the following thread.
http://bbs.homeshopmachinist.net/threads/63038-Fun-with-Worm-Gear-Drives?highlight=worm
The interesting thing about a worm gear, is that once you get beyond a 40:1 ratio, they won't feed back to the driving shaft. This feature has been successfully used on many small hand winches. I still have the worm drive created back in 2014, and I may do something with it.

[crueby]

What about a clutch plate setup, one fixed, one turned by the engine. Screw or lever the fixed one into the other to give load, no load when apart? Or drive a pump, close down the nozzle for load?

[Brian Rupnow]

That would work Chris, but I want it to be fully automatic, without any intervention by me.

[doubletop]

Brian

A big spring one end secured to the floor with the engine pulling the other end over a pulley would give you a progressively increasing load. At the fullest extension some form of trip mechanism or electrical switch that actuated/deactivated the clutch?

EDIT

Lateral thinking time - How about as second hand one of these, or create somthing similar.




The load is variable by the bowden cable and is a function of the gap between the rotating disk and the magnet cluster (left side). Put a V groove in the flywheel (right side) for the motor to drive. Arrange for the Bowden cable to be extended/retracted cyclically (no pun)

You could do something similar with a set of neo magnets and a disk. A slow geared elecric motor and cam varying the gap.


Pete

[Brian Rupnow]

A very important milestone reached today. You have all heard me making reference to my "Fat mans walk" which I started after getting a "too high" blood sugar report on a blood test. I have been walking a mile a day since then, and forgoing my regular intake of chocolate bars, donuts, soft drinks, and any other sweet things. As of this morning I have lost 30 pounds.  I find that fact amazing. After three months of such extreme dieting and exercise, I'm finding it more and more difficult to stay on such a monastic diet. I have already told my wife months ago that if I ever lost 30 pounds, I was going to go down to the Dairy-Queen and have a banana split. Today could be the day!!!

[michaelr]

Don't undo all that hard work you have put in keep away from the Dairy-Queen, Will Power it's called. 

Mike.

[Brian Rupnow]

This morning I ran the engine with my worm drive varying load. It worked, but not as well as I wanted it to. I made a video, but I'm not happy with the results. The big weight (two pieces of flatbar taped together) did make the engine run in the miss cycle at a very brief angle near the top and bottom of its swing, but when the offset weight went over the top of it's arc, it still resisted turning easily. So, while the engine should have been popping and missing thru the full 180 degrees of swing as gravity pulled the weight down, it kept on hitting trying to overcome the worm gear and worm binding. Engine was supposed to miss under no load condition for 180 degrees of arc while gravity pulled the arm down and then work without missing while the weight was lifted up thru 180 degrees. It didn't work out that way. I have just ordered a one way clutch bearing, and when it gets here we will try things again.

[gunna]

..... I have been walking a mile a day since then, and forgoing my regular intake of chocolate bars, donuts, soft drinks, and any other sweet things.......

Sorry Brian, couldn't resist this. The doctor told my wife to walk a mile each day and she started to do it. A mate asked me how she was going and I replied, "don't know, last I heard she was at the border and heading interstate!"

Congrats on your success with the walks,
Ian.

[Brian Rupnow]

Ian--My walk is about 1/2 a mile up hill, but then I come back. Second half of the walk lets me cool down from the first half.---Brian

[Admiral_dk]

Sounds and looks to me like you are doing great Brian 

[Brian Rupnow]

Today I received my one way clutch bearing in the mail. It looks exactly like a sealed ball bearing, but it definitely has the "turn only one direction" feature. I am going to mount it in the offset weight arm, so that as soon as the engine has lifted the weight arm over the top, the arm will swing back down due to gravity, and having no "binding force" transmitted back to the engine.

[Brian Rupnow]

The one way clutch bearing had an inner diameter of 12 mm, so I made a hub of cold rolled steel, put two set screws in each end and drilled/reamed it 0.312" for the 5/16" shaft it is going to mount on. The hub is pressed into the bearing with an interference fit of .0005".

[Brian Rupnow]

Well, the one way clutch bearing works exactly as advertised. I'm impressed. However--the set up didn't work. The one way clutch bearing was mounted in the steel bar which gets rotated, but--Once the bar goes slightly past vertical, it free swings thru almost 350 degrees. The engine has to hardly work at all. I thought for a moment that I had invented perpetual motion.

[crueby]

Put a big paddle on it for air resistance?




Hmm, ditch the clutch, put a lightweight cup on the rod and a pan of water. Lifts the weight of water going up, it pours out at the top and little weight on way down?

[Brian Rupnow]

Chris--I am going to either give up on this or try a totally different approach. The absolute best video of the engine hitting under load and missing under no load was the video in which the string with a weight on one end  went over a pulley and down to a small winch drum attached to the clutch. My current system with the worm gear gives the engine too much mechanical advantage--it never sees enough load to function the way I want it to. In a perfect world, the winch drum would turn clockwise for a measured number of turns, then stop and turn counterclockwise for a measured number of turns. I want this loaded and unloaded cycle to repeat, with no intervention from myself. I actually have enough ceiling height to put the top pulley that the string goes over up higher, and have something attached to the string running down to the weight in two places. At the upper and lower limits of travel, the "thing" attached to the string would move a lever, which would reverse the drum rotation. I have looked at all manner of "automated reversing systems" and they either beyond my machining capabilities, or look like they wouldn't work. I am in no rush to build another engine, so am still searching for an automated reversing system that looks like i could build it. There is one in the booklet "507 Mechanical Devices" that shows promise, but it would be a lot of work.
<a href="https://www.youtube.com/watch?v=JRtmoje5uJA" target="_blank">http://www.youtube.com/watch?v=JRtmoje5uJA</a>