Flat Belt Reversing Mechanism

[Brian Rupnow]

John--thanks for having a look and for the suggestion.--What you are suggesting could happen----Brian

[Johnmcc69]

I'm thinking maybe a lever/spring mounted tensioner that disengaged when you engage the reverse lever. This would take the tension off the belt & make moving the belt easier. Much like disengaging a clutch. Tension on the belts while "driving" & slack while shifting the belt.

[Brian Rupnow]

Here we have a video of the first "run in" of the flat belt reversing system. I do not have the belt shifter installed yet. This is just a run in for half an hour to take any tight spots or binds out of the mechanism. I have to have everything moving very freely before I reach a final decision on center to center of belt pulleys. NOTE THAT IN THE VIDEO I TALK ABOUT A 30 MILLIMETER SPACER--SHOULD HAVE SAID 0.030 THOU.---Brian
<a href="https://www.youtube.com/watch?v=6yLrEYt39Tg" target="_blank">http://www.youtube.com/watch?v=6yLrEYt39Tg</a>

[Brian Rupnow]

For those of you who are asking about a crown on the pulleys.---The long single pulley, which is being driven by the flat belt in the video will eventually end up as the "driver", not the driven. The belt has to scoot sideways from one end of the pulley to the other when I shift the belt, so it will not have any crown. The two outer pulleys at the other end MAY have a crown if I determine that they need it. The center pulley at the far end may get a crown, or may not. Before I crown any of the pulleys, I have to build the belt shifting device and install it. It is very possible that the belt shifting mechanism will make the belt hold position so that none of the pulleys require crowns.---Brian

[Brian Rupnow]

I've just had a small surprise---In all the solid models I have posted, you will see that I have the belt shifting mechanism closest to the three individual pulleys. In reality, as per testing just done in the garage, the belt shifts sideways far easier if the shifter mechanism is close to the one long single pulley which is the driver. (I have changed the 6" pulley around to drive the single long pulley since the video was posted.)

[Brian Rupnow]

And---We have a winner. Rather crude set-up and background, but everything works as I had hoped. I will clean things up a bit and post a better video later, but this first run has made my day!!!---Brian
<a href="https://www.youtube.com/watch?v=P3UGdEAbdhU" target="_blank">http://www.youtube.com/watch?v=P3UGdEAbdhU</a>

[Brian Rupnow]

Today was a good day. The mechanism works exactly the way I had anticipated. This is the first thing I have built in ages that didn't cost me anything. I had all of the material left over from other projects except for the end plates. I was at a customers, looking at a job, and I happened to mention that my next stop was going to be at a metal suppliers to buy some 4" x 3/4" aluminum. My customer walked over to his rack and gave me a piece of aluminum long enough to get two end plates out of!! I'm not horribly impressed with using a pair of vice grips to move the belt shifter, so I may do something a bit classier there. As far as automating the belt shifter, I don't think I'm going to try to do that. The system doesn't have to transmit a lot of power. I know that belt tension plays into how much power can be transmitted, but my main aim in building this mechanism was to see about the ability to reverse a shaft, not to transmit a lot of power.

[Brian Rupnow]

Now we get to the part I was talking about earlier, where not all things scale down that well. I have proved by my tests yesterday that this mechanism does indeed allow reversing the output from a flat belt. The vice grips were very crude but they did allow me to move the slider to shift the belt. Now I have designed something with a lot more "cool" factor, but it forces me to do some things which are not scalable. My hand which operates the shifter mechanism is "full size", therefore, some of this mechanism has to bridge the gap between miniature and full size. You will see that the end-caps on the shifter rods have been changed to a shape that extends from side to side forming a bridge. Mounted to the top of this bridge is a 2" long piece of 24 dp rack. Meshing with the rack is a gear quadrant with a 6" handle that when inclined 30 degrees to the right or to the left moves the slider thru its full range of movement. The large dark blue piece at one end of the frame is the support for the pivot shaft .

[Brian Rupnow]

I haven't disappeared--I've just taken a short break. I have a friend who, over the years has supplied me with a small fortune in brass angle and brass hex rod. I asked if there was anything I could do for him in return, and he answered that he would like to have a small cable winch to mount under the back of his truck to winch the spare tire up into place. He supplied the aluminum and the gear and pinion and this is what I built for him.
<a href="https://www.youtube.com/watch?v=EcngNNqdUso" target="_blank">http://www.youtube.com/watch?v=EcngNNqdUso</a>

[Brian Rupnow]

Slowly and somewhat randomly, the changes are happening to put a reversing handle and sector gear on the reversing mechanism, to make it match the most recent 3D model. There is nothing difficult here, just somewhat time consuming. The overhead bridge that will support the gear rack was finished off this morning. The round blue disc is destined to become an 82 tooth gear. I won't cut teeth all the way around it, because I only need a total of 62 degrees to interact with the rack to move my belt shifter from side to side. I find it almost sinful to be doing things in my shop in the middle of such incredibly beautiful weather. My good wife would gladly lay around all day in the air conditioning, but I have to get out and enjoy this weather while it is here. In the middle of January and February its remembering weather like today that keeps me alive until spring. If you are enjoying this thread, give me a shout.---Brian

[Brian Rupnow]

HA!!!--Just went out with good wife, oldest son, and second youngest grandson to the Dairy Queen. Banana splits all around. Life is good. Now, back to work on the beast.

[Brian Rupnow]

If any of you think that maybe I'm making this up as I go along---You're absolutely right. I have finished and installed the new bridge that connects to the end of the belt side-shift rods, and mounted a 2 1/2" length of 24 DP gear rack to it. The blue disc which is destined to become a sector gear is attached to a piece of 3/4" diameter cold rolled steel with a 5/16" shoulder bolt. I don't want to take a chance on it spinning while I am cutting gear teeth on it, so I have drilled and pinned it in place with a piece of 1/8" cold rolled steel. You can see the shape it will eventually have scribed on the face of the disc.

[zeeprogrammer]

HA!!!--Just went out with good wife, oldest son, and second youngest grandson to the Dairy Queen. Banana splits all around. Life is good. Now, back to work on the beast.

Lucky. I might get the daughters and grand-daughter to go...but not the wife. Which means taking the daughters and grand-daughter may mean personal injury to myself.

Got any Dairy King's in your area? That was the place to go after school. And it was right across the street from school.

[10KPete]

Right on the corner on the way home from school... man-oh-man I can taste it now....

Good times.

 

Pete

[MJM460]

Hi Brian, I am one of the many enjoying every post on the development of this mechanism.  I never miss it.  Keep up the descriptions of your thought processes and the pictures.  Also looking forward to what you will dream up to drive with it.

MJM460