Cush drive unit

[Rick S.]

I've been thinking about building an enclosed chain cush drive for a while now.
Artie's aluminum casting thread got me thinking again.

I finaly did get around to checking out the extrusion die costs. I wasn't able to get a price because I'm told we get that done for free. (I guess when you buy 100's of miles of the stuff they roll in the cost of the die.)

Here is the cush sprocket. It will be mounted on the centeraxle between the cv's.
The outer plates will have 3" id bronze bearings pressed in. I may end up replacing these
with thin ball bearings, but I think the bronze will do the job.
8 polyurethane slugs fit inside the hub and are driven by a 1" wide spider.

Will it work?





 

[Boostinjdm]

Damn it rick, ok how much for one?  Instead of the single sprocket, could you wiggle in two with a center spacer?  I'm sure you could...

[fabr]

Sure it will work. Actually I've got just that type of thing drawn up myself.Although I believe you can simplify your design by using the PU spiders like engineer and I am using for our cushion coupler.

[Boostinjdm]

I think collaboration is key to success.

[Rick S.]

Two chains could easily be done by making the covers the sprockets.
Not a bad idea either, but it would add a little width. Right now the type 4 cv flanges are 4-1/2" apart. 930's would be 5"
I did look at standard spiders, but the way I have it designed, it was easier and cheaper to do it this way. For $17 I can buy 24" of poly rod. enough for 3 units. Plus I can play around with different durometers without spending too much cash. 

[Boostinjdm]

sounds like you got a good plan Rick.  What about you Fabr?  Any eye candy?

[trojan]

Kudos! I think it will.

Is the spider made of two 1/2 inch plates too?

Experimentation is BEST You could get two part PU and mix it up yourself as you like and pour it into the unit and let it set?

[Boostinjdm]

a few slight mods and I bet you could forget the bronze bushings.  or at least make it a more bearing friendly size.  Do you have any pics of the center?  Why such a big hole in the side plates?

[Rick S.]

The spider is one piece 1" thick waterjet with a 2" id.  Everything sandwiches together with eight 5/16-18 x 3"  soc. hd. cap scrs. The slugs are a slip fit in the housing. Yes they could be cast. We have used the 2 part PU before at work.

[Boostinjdm]

I was thinking two smaller chains to keep the sprocket diameters reasonable and to smooth things out.  I also figured that with two sprockets you could just bolt them on each side of a center flange so they would be easily replaced without disassembling the whole unit. Do you have any post machining to do, or do the parts go straight from cutting to assembly?

[Engineer]

I was thinking two smaller chains to keep the sprocket diameters reasonable and to smooth things out.  I also figured that with two sprockets you could just bolt them on each side of a center flange so they would be easily replaced without disassembling the whole unit. Do you have any post machining to do, or do the parts go straight from cutting to assembly?

Looks like countersink and thread on both of the outer parts.  I am sure the inner will need bored to size, etc.

[Rick S.]

The side plate holes are large because the tube spacers are 3" od x 2" id. This spacer also has the eight bolts running through it. I need the large diameter to keep these bolts spread as wide as possible. The ball bearings at the cv flanges are 75mm id.
the larger sprocket bearing surface will handle the loads better.
I think bronze, because the sprocket is only rotating a couple of degrees on the bearing.
I'll part off thin bronze bearings from a 5" long standard bearing.
No pics of the center yet. I just started making this tonight after work.

[Boostinjdm]

Looks like countersink and thread on both of the outer parts.  I am sure the inner will need bored to size, etc.

I see that, duh. what about where the slugs go?  any smoothing? Or truing up the spacers?

[Engineer]

How will the inner be connected to the shaft?  Splined or welded?

If you started with the inner spider component at 1.5-2" thick, (wide) you could turn a shoulder on each side for the bronze to ride on.  You could make the spacers a bit thicker, and then use a hat bushing on each side cut down to the width you desire, the hat could be inside on each side, then any thrust would be controlled by the bushings.  Or just drop a thrust washer in.

Or mabey I don't understand where your headed. 

Overall it looks like it should work.

[Rick S.]

I wouldn't want to put the sprockets on the side plates, because then screws would be in shear. Right now the PU slugs react on the sprocket itself. The screws see some shear but not nearly what they would if the side plates were sprockets. For assembly all I had to do was chase and tap the holes and add the c'sinks. The flat hd. screws act like dowels to keep the side plates located. Next I have to clean up the center bore and open up side plate holes for the bearings. This will be done on the lathe with the sprocket assembled like you see it. The 5 pieces will then be stamped so they always go together as they were machined.
I'm also turning the od of the bronze bearings and leaving a 1/16" thick flange for thrust.
no splines or welding it's all torqued down with the eight bolts. (The spider has 8 holes on a 2-1/2" bolt circle.)