Author Topic: high torque and RPM flex drive; advise needed  (Read 8707 times)

Offline rschilp

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high torque and RPM flex drive; advise needed
« on: December 04, 2012, 08:57:19 AM »
Need some design help.

I'm building a somewhat customized '32 Chrysler 3 window coupe. The powerplant is a 1934 Pierce Arrow designed 462ci V12 and came originally from a 1941 Seagrave firetruck. I've mounted a 6-92 blower (inline 6, 92ci per cylinder) in line with the crankshaft of the engine to be driven from the crank directly.

This is very similar to the design that the blower bentleys used in the late 1920's and the Potvin design from the 1960's. I don't have many blower bentleys around to study and copy designs from and the potvin model was based on a custom timing cover and a rigid mounted blower. My intent is to make the blower somewhat flexible mounted from the engine, allowing for some movement.

What kind of linkage / flex drive could I put between the crank and the blower?

For reference; operating range will be 800 to 3,200 rpm and the engine with the blower and injection will put out in excess of 500 ft lbs of torque.

And as this thread is useless without pictures I've added some, the bentley is from the collection of Ralph Lauren, the others are my project.

Offline 75Plus

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Re: high torque and RPM flex drive; advise needed
« Reply #1 on: December 04, 2012, 09:52:11 AM »
You might consider adapting a CV joint from a front wheel drive car. Torque handling would be more than adequate and less than perfect alignment would be tolerated.

Joe

Offline rschilp

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Re: high torque and RPM flex drive; advise needed
« Reply #2 on: December 04, 2012, 10:11:57 AM »
You might consider adapting a CV joint from a front wheel drive car. Torque handling would be more than adequate and less than perfect alignment would be tolerated.

Joe

Joe, that's a great idea, but I think those are a little too long? I've only got about 4" of total space between the blower snout and the face of the balancer on the crankshaft. If I move the blower further out it will hang out beyond the fenders and past the bumper.

Offline David Jupp

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Re: high torque and RPM flex drive; advise needed
« Reply #3 on: December 04, 2012, 10:26:18 AM »
Depending upon how the whole things is supported, you might also need to allow for lateral mis-alignment as well as angular.  A single CV joint will be great for angles, I'm not convinced how well it will handle things if the two axes don't intersect at a point in centre of the joint (others can probably advise better than I can).

A gear coupling could be very robust and compact - they can tolerate minor misalignments of both types.  Because they have many teeth, the torque transmitting capability can be high.

Offline rschilp

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Re: high torque and RPM flex drive; advise needed
« Reply #4 on: December 04, 2012, 10:33:04 AM »
Depending upon how the whole things is supported, you might also need to allow for lateral mis-alignment as well as angular.  A single CV joint will be great for angles, I'm not convinced how well it will handle things if the two axes don't intersect at a point in centre of the joint (others can probably advise better than I can).

A gear coupling could be very robust and compact - they can tolerate minor misalignments of both types.  Because they have many teeth, the torque transmitting capability can be high.

My best design so far is a double gear with a chain. Two gears closely lined up with a doube roller chain going around both. I think that is what you are refering to here as well.

Offline redshift

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Re: high torque and RPM flex drive; advise needed
« Reply #5 on: December 04, 2012, 11:15:54 AM »
An Oldham coupling should fit the bill, short in length and will take a little misalignment in all directions.
You should be able to make it yourself with all the gear you have
Regards
Dave

Offline David Jupp

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Re: high torque and RPM flex drive; advise needed
« Reply #6 on: December 04, 2012, 01:46:55 PM »

My best design so far is a double gear with a chain. Two gears closely lined up with a doube roller chain going around both. I think that is what you are refering to here as well.

Not quite - but similar idea - 2 involute gears on common axis - rigid toothed collar around both gears, somewhere along the line the there is some modification of the tooth geometry to cope with minor mis-alignments.

Offline 75Plus

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Re: high torque and RPM flex drive; advise needed
« Reply #7 on: December 04, 2012, 06:22:12 PM »
An Oldham coupling should fit the bill as they are adaptable to most any situation if you can build your own. If you are not familiar with Oldham you can see one, with animation, here:



Joe

Offline rschilp

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Re: high torque and RPM flex drive; advise needed
« Reply #8 on: December 04, 2012, 07:56:39 PM »
I like the oldham coupling, I even have some nice pieces of Nylon material that may make a good center disc.

How well does the oldham coupling work with a misalignment at an angle?

Offline sebwiers

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Re: high torque and RPM flex drive; advise needed
« Reply #9 on: December 05, 2012, 12:35:26 AM »
Why not literally a flex drive?  That is, a couple (heavy!) coil springs nested one inside the next, wound in opposite directions, or other flexing material?

Another option would be a varient on a a cush drive (at least that's what I know it as, from motorcycle rear ends) ; each side would have protruding fingers that mesh together, with something like urathane bushings between them the two.

Here's a video that briefly shows what look like workable examples of both types I mentioned. 


Either type can (afaik) tolerate both angular and skew misalignment.

Offline Lew_Merrick_PE

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Re: high torque and RPM flex drive; advise needed
« Reply #10 on: December 05, 2012, 11:32:24 AM »
I like the oldham coupling, I even have some nice pieces of Nylon material that may make a good center disc.

How well does the oldham coupling work with a misalignment at an angle?
It depends on the size of the coupling and material used for the compliant insert.  5° of misalignment is the generalized book value -- though I have used them as high as 12° with elastomeric inserts.

Offline BillTodd

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Re: high torque and RPM flex drive; advise needed
« Reply #11 on: December 06, 2012, 09:55:58 AM »
I'd have thought you be better off with a conventional pair of UJs and a short shaft, with perhaps a second pair between the blower and the engine block to take the torsional load.

If engine and blower are tightly coupled,  perhaps an Oldham coupling would be fine, but it may try to force itself apart at the slide and any significant misalignment will result in vibration (how would you lubricate it?)

Bill

[edit]

If the blower is close coupled these look ideal:

http://www.darossi.com/supercharger-store/supercharger-coupler.html
Bill

Offline rschilp

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Re: high torque and RPM flex drive; advise needed
« Reply #12 on: December 18, 2012, 01:56:37 PM »
I'd seen that coupler, it goes between the shaft of a small (really a baby) supercharger and the pulley where the belt drives it.

My supercharger is MUCH bigger (read more torque required) and does not have a belt, the main shaft of my supercharger is lined up with the crankshaft of the engine (low and in the front) so I need a straight through coupler. The engine will be mounted on rubber bushings, the supercharger will be mounted to the engine, with a rubber mounted support on the rear. The overall length of the setup, from rearmost engine mount to supercharger is 7 feet, with rubber mounts on both ends and the front of the motor (~4ft from the back) I don't think I have the space (or the weight) to rigid mount the supercharger. So a slight angular and linear misalignment may occur under heavy load or acceleration.

The conventional pair of universal joints would be great, but not enough space for the ones that can handle the load, so I need something a bit more elegant. Some of the earlier posts have good ideas that I'll build as a prototype sometime soon once I get back to the shop.

Offline phillip

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Re: high torque and RPM flex drive; advise needed
« Reply #13 on: December 27, 2012, 11:15:11 PM »
"If it’s true that our species is alone in the universe, then I’d have to say that the universe aimed rather low and settled for very little"

Offline John Hill

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Re: high torque and RPM flex drive; advise needed
« Reply #14 on: December 28, 2012, 03:55:27 AM »
No doubt the CV joints from a FWD car have been suggested by maybe the inner joint would be better as they (usually ?) include clearance for things to slide in and out a bit.
From the den of The Artful Bodger

Offline RadRod67

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Re: high torque and RPM flex drive; advise needed
« Reply #15 on: January 31, 2013, 11:38:54 AM »
Uni joints run with some eccentricity so for this application i would advise against them. If you dont want to use an elastomeric your options are Gear, Grid or disc type couplings and I think the disc type might be your best option. If you were thinking elatomeric the common pin and bush (David Brown down here) would be my first choice you could also look at Centa for example for more advanced designs.

Regards,
Rod.