Line-Shaft Clutch

[Brian Rupnow]

Well, it sorta/kinda works. The angle on the contact surfaces which I arbitrarily picked as being 45 degrees is too steep. I have a 45 degree angle on the nose of that 3/4" diameter slider and with the lathe running at about 60 rpm I can hold the pulley drum from rotating with a finger. If I use my other hand to force that 3/4" diameter slider against the "arms", the shoes do expand and make the drum rotate. However, I am sure a shallower angle will make things work with a lot less effort.

[Brian Rupnow]

I changed the angle on the end of that 3/4" slider to an included angle of 60 degrees instead of 90 degrees, and it made a tremendous difference. The clutch is working just as I hoped it would. You have to keep in mind that those sliding shoes only have to move about .015" to make the difference between engaged and disengaged. If they had to travel any real distance, then I'm sure they would "cock over" and bind badly. I can feel a video coming on---

[90LX_Notch]

Brian-

Nicely done.

Based on what I see, I do think 1/2 scale is feasible.  The challenge is of course the t-slot.  However, I believe that John's diarama would work out to be 3/4 scale of your clutch (3/16 vs 1/4 shaft).  This makes it very attainable.  At 1/2 scale the 4-40 screws work out to 0-80 and at 3/4 scale they would be 2-56.  0-80 can be nerve wracking; 2-56 isn't bad.

-Bob

[J.L.]

Nicely don Brian! 

Brian, if I may, through you to Bob.

Hi Bob,
The diorama scale is 1/12.
John

[90LX_Notch]

John-

I understand.  I'm refering to Brian's clutch as 1:1.  Your 3/16 shaft would scale to 3/4 of Brian's clutch.  He used a 1/4 inch shaft.

-Bob

[Brian Rupnow]

This morning I took successive cuts from the outside diameter of the coned 3/4" piece until I had it down to a diameter that would just slide between the arms under slight pressure to open them wider and engage the sliding shoes with the clutch drum. This was not something that could really be calculated with any accuracy. It was purely "turn a little bit and then try it" engineering. With my model, the "ideal diameter" should have been 0.520" diameter. In actuality, it was exactly 0.500" diameter, which is pretty darned close, considering the build up of tolerances and the shape of the arms. I have provided two pictures, one showing the clutch in the "not engaged" position--The "Not engaged" position shows a gap of 0.100" between the nose of the sliding cone and the brass hub. The "engaged" position shows 0 gap between the nose of the sliding cone and the brass hub. And yes, that is a Canadian quarter laying in the foreground to give e sense of scale. Our quarter is the same size as an American quarter .

[Brian Rupnow]

It doesn't always start with a pretty 3D cad model. Sometimes when I'm hashing out exactly what I'll do next, I resort to good old pencil sketches to determine the direction I will take. I will now go from this preliminary sketch to a 3D cad model where I can input all the math data to create accurate models and detail drawings from.

[Brian Rupnow]

So, we end up looking like this. The panther pink pulley is driven by an o-ring drive belt from one of my engines, to turn the lineshaft. When the clutch is not engaged, the green pulley drum just sets there and does not revolve. When the clutch is engaged, the pulley drum does turn, and will drive an o-ring belt that powers one of my "work, work, work mechanisms, probably the moving staircase.

[10KPete]

That's a pretty neat bit of work, Brian. I'm looking forward to you building that into one of your engine/load set-ups. One small concern, that probably won't mean much for the limited service intended, is the lack of compliance or elasticity in the mechanism. A tiny amount of wear in the clutch surfaces or the actuator cone and arms will result in no engagement. Maybe the arms could be lengthened and made thin to act a springs......

Pete

[Brian Rupnow]

That's enough for today. My back hurts!! Tomorrow, I hope to make the lever mechanism that will engage and disengage the clutch.

[Brian Rupnow]

That's a pretty neat bit of work, Brian. I'm looking forward to you building that into one of your engine/load set-ups. One small concern, that probably won't mean much for the limited service intended, is the lack of compliance or elasticity in the mechanism. A tiny amount of wear in the clutch surfaces or the actuator cone and arms will result in no engagement. Maybe the arms could be lengthened and made thin to act a springs......

Pete

Pete--If you go back and look at reply #9 you will see that on the original line shaft clutches, the tapered bits on the end of the arms have a thread in them. I think that was how they adjusted to compensate for wear and to make sure that both arms extended equally. Of course, here in "Model world" I don't have to be quite as concerned with wear. Now that I have actually made the arms, I see that I could have incorporated a threaded fastener into them to provide the same service, however, as in most things I build, this is my 'prototype", even if I never build another one. Before this week, I always wondered about this type of clutch and how it actually worked. But----There are about a million mechanical things floating around in the back of my mind that I kind of wonder about, but unless I make a conscious effort to recreate the design and build one myself, they are only vague thoughts. One thing I can say for this clutch, based on my experience so far---There isn't much "between" to this clutch. It's either ON or its OFF. Probably it transfers less shock to the driven machinery than a dog clutch would, but there isn't a whole lot of "slippage". There doesn't seem to be any replaceable lining on the friction shoes either from what I can see in the photograph in post #9.

[gerritv]

Considering how ubiquitous these devices were at one time it is surprisingly difficult to find details. I even tried trolling old patents as well with little luck.

[J.L.]

Hi Brian,

Wonderful work Brian. I have been hammering out a prototype as well. Drawings are up on the diorama thread.

Great weather as we approach Thanksgiving.

Cheers...John

[Brian Rupnow]

Jeez John--You don't fool around, do you!!! Nice work on your clutch. Mine is all finished and seems to work well. If I can find the energy to get things set up, I'll post a video. I think since I already have my Kerzel hit and miss out on the bench I will use it as a driver, thru the newly made clutch, to the steel ball elevating staircase. if everything works as I hope, I will put up a link to the drawings.-- Most line shaft clutches I remember seeing had the line shaft overhead, and a long handle that hung down for the machine operator to pull to engage the clutch. Of course my memories are from sawmill stuff in the 1950's.---Brian

[J.L.]

Hi Brian,
Thanks!
Brian, I've got to get my head into your videos and posts. I apologize for not taking time to search them out.
Cheers...John