Author Topic: auto CV joints for direct drive gen.  (Read 8374 times)

bitsnpieces1

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auto CV joints for direct drive gen.
« on: May 28, 2006, 09:25:53 PM »
  Has anyone tried to use an automotive CV joint on a direct drive generator setup.  It should allow for some angular misalignment between the engine and the gen head.  Regular U-Joints aren't supposed to be angled by much.  Les
Lister Petter AC1, Listeroid 12/1, Briggs & Stratton ZZ, various US Mil. surplus engines. Crosley (American) 4cyl marine engine(26hp).

GuyFawkes

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Re: auto CV joints for direct drive gen.
« Reply #1 on: May 28, 2006, 09:44:32 PM »
the question you should be asking is why have angular misalignment, why not just line things up properly, it's quicker and easier than buggering about with UJs...
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Original Lister CS 6/1 Start-o-matic 2.5 Kw (radiator conversion)
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Original Lister D, megasquirt multifuel project, compressor and truck alternator.
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bitsnpieces1

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Re: auto CV joints for direct drive gen.
« Reply #2 on: May 28, 2006, 10:11:22 PM »
  I'm looking at using my Listeroid as a changeable powerhead/prime mover.  I would need to be able to connect/disconnect the gen. head as needed, probably using a short stub shaft [6-12"??].  In my former work we used direct connections, but, when you're talking about 3 ph 480v 200hp 3400rpm motors you're talking about 2-5 ten thousandths allowable misalignment in all three dimensions and still using some type of flexible joint.  We used to use Ujoints, on 'close-coupled' to shafts up to 75 ft long.  I would rather stay from that degree of alignment every time I switched the drive.
  I was planning on setting up the engine to use a setup like a tractor PTO connection.  Also the engine won't neccesarily (??sp) be a fixed mount. 
Lister Petter AC1, Listeroid 12/1, Briggs & Stratton ZZ, various US Mil. surplus engines. Crosley (American) 4cyl marine engine(26hp).

Firebrick

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Re: auto CV joints for direct drive gen.
« Reply #3 on: May 28, 2006, 11:20:57 PM »
U joints can be angled quite abit (farm equipment is puts up to maybe 65 hp at 20 degrees without problems) with the low power you are talking about but they speed up/slow down (greater the angle, the more the affect)as they go through the rotation and add vibration if the angles are not equal which is not good in some applications. Also U joints are for slow speed applications, in farm equipment 540 is what they rotate at, the 1000 rpm pto shafts are CV joints.   The  car sized CV joints are strong enough for the hp of a lister several times over.  Have you thought about a flat belt?  Alot of old farm equipment was driven this way with good results, maybe up to 60-70 horsepower in some cases and up to 25-30 feet away.  The alignment wasnt that critical and the belt absorbed shock loads as well. If you are putting the engine close to the driven equipment an auto serpentine belt around the flywheel would work well and it would allow for different gear ratios without gearboxes, just change the pulley size on the driven equipment. 
 
While not exactly sure but the single power pulse of a lister might be rough on any type of shaft joint.  We had a john deere 60 running a high capacity small square baler.  It would tear up drive shafts very quickly (maybe 2 a year) because of the high torque power pulses of the 2 cylinder engine.  Put a 6 cylinder 970 case which has twice the horsepower and we never replaced a U joint again.

bitsnpieces1

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Re: auto CV joints for direct drive gen.
« Reply #4 on: May 29, 2006, 12:39:16 AM »
  It has to do with design parameters.  Such as:  #40 chain used on a lot of motorcycles is designed to transmit power form about a 1/4 - 1/2 hp electric motor for about 10 yrs in an oil bath.  U-Joints aren't designed to run at more than a 4 degree angle, run them at more and they have pecular angular mementum changes that you see as jerking and speeding up/ slowing down and will wear them out very quickly.  The reason they were in the hay baler is that they are cheap and fast to change out, not because they last a long time.  Auto CV jointas are engineered to run at angles almost as great as 90 degrees from straight and do so smoothly, so, they last a lomg time. 

  I'm trying to use something in a shaft type drive that will last almost as long as the engine itself.  I'm not trying to be agruementative just trying to find out if anyone has tried them.  Any Mechanical Engineers on the forum should be able to explain the design factors. 
Lister Petter AC1, Listeroid 12/1, Briggs & Stratton ZZ, various US Mil. surplus engines. Crosley (American) 4cyl marine engine(26hp).

swedgemon

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Re: auto CV joints for direct drive gen.
« Reply #5 on: May 29, 2006, 02:35:17 AM »
The problem with a single U-joint is the vibration mentioned earlier...as power at a constant speed (lets say 600 rpm) is transmitted through a Hooke's joint (U-joint) an angle, the speed on the other side will vary, with two angular accelerations and two angular decelerations per revolution (590 to 610 rpm, in this example).  Now if there is a typical pto shaft (Cardan shaft), with a U-joint on each end, the deflection angle the same at each end and in proper "phase", the speed variations will be damped out and the output will be a constant 600 rpm in the above example.  Being "in phase" means that the yokes at each end of the intermediate shaft are in the same plane...if the yokes are even one spline tooth (at the slip joint) out of phase, heavy vibration, short cap bearing life, etc., will be there to plague you. 
Each Cardan shaft also has a "critical" speed, which is determined by intermediate tube wall thickness, and length of the tube.
Another little often-ignored detail on these devices is that if run straight-through, with no deflection, the cap bearings will Brinnell and fail.

There are at least four types of CV joints...Citroen, Rzeppa, Bendix and a "double-U-Joint".  The Bendix type is seldom seen, unless you have an old Vietnam era duece-and-a-half or 5-ton Army truck (anyone ever replaced a steering axle seal on an Army 2 1/2 ton?).  A Rzeppa joint is usually on the outboard (steering) joint on a modern front-drive auto, with a Citroen joint (3 cam followers and a tulip) inboard, next to the transmission.  A "double-U-joint" is a back-to-back set of U-joints.
I have seen heavy industrial Cardan shaft units run at 1200 rpm, although the cap bearings had short life (about 18 months).  I have also seen a failed Cardan shaft on the back side of a paper machine...talk about a nasty "radius-of-destruction"...
Suggest you seriously look at a Lovejoy (spider-type) coupling if you are using direct drive.
Swedgemon
GM-90   6/1
Somewhere in Kentucky

Firebrick

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Re: auto CV joints for direct drive gen.
« Reply #6 on: May 29, 2006, 07:34:47 AM »
Maybe if it is all about design parameters maybe you should tell us yours?  What engine are you running?  Since you posted on a lister forum I suppose a lister 6/1.  If so how are you going to direct drive a generator head?  Most are set up to 1800 or 3600 rpms.  This is why I suggested belts,  not to argue.  I think CV joints would work well but not for the lifetime of the engine.  I doubt there are many "mechanical engineers" here but many of us have alot of real world experience. 

I have worked on everything from flex shim couplers and specialized drive shafts on helicopters and tuboshaft engines to CV joints on trucks and u joints on a mulitude of equipment.  No shaft drive that will allow for more than a degree of miss alignment will last the life of a lister, none.   10,000 hours to maybe even 50000 hours with erratic power pulses is not kind to any angled joint.  As swedgemon stated failed driveshafts are not pretty and damn dangerous.  Love joy or flex shim couplers would allow for the lifetime you are looking for but not the versitility or angular misalignment. 

Also a real problem that you will face with shaft drive is if the equipment is not solidly mounted to a common frame is torque reaction.  With a lister being top heavy and mounted on a cart that is small enough to manuver I could very well see the engine flip on its side or move in a way to damage/destroy the driveshaft. Farm machinery has several tons and wide wheel bases to deal with this but you can still feel it.  I have seen a rotory mower(bushhog) flipped when the owner used a grade eight bolt as a shear pin and the gear box locked up due to a lack of oil/destroying it self.  twisted the tongue up and really made a mess of things even though it weighed nearly 500 pounds and was 6 foot wide(3 foot from the pivot axis, the driveshaft in this case)


nutman

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Re: auto CV joints for direct drive gen.
« Reply #7 on: May 29, 2006, 11:03:01 AM »
Not long ago, I saw a picture of a 12/2 hooked up to a PTO generator using a shaft with two u-joints, probably off the shelf farm supply shaft. It should last a very long time with proper alignment. I would be more concerned about the power loss by running the engine at 540 RPM's.

swedgemon

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Re: auto CV joints for direct drive gen.
« Reply #8 on: May 29, 2006, 11:51:48 AM »
Hey Firebrick,
...belt drive, no arguement...on a Satyajeet GM-90 from Mike Montieth.
Swedgemon

bitsnpieces1

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Re: auto CV joints for direct drive gen.
« Reply #9 on: May 29, 2006, 12:49:26 PM »
  OK, now we're getting somewhere!  I have a Lister-Petter AC1 6.5hp 3600rpm 1 cylinder.  I have a Listeroid 12/1 on the way.  I'm comsidering a Mini-Petter.  One application I have will be a fixed mount, another will be as a moveable prime mover.  I'm looking at a PTO type connection, ie: quick connect/disconnect.  It will be used to drive a gen. head, then a welder, then a limb chipper, then an air compressor, then ? who knows.  This will most likely be the AC1 or the Mini-Petter.
  I'm aware of the belt type drive, but, I'm looking at alternatives to that.  I would rather stay away from U-Joints for the above reasons of weird torque reactions, if doable.  I was thinking of auto CV joints that can feed-through a couple hundred hp at all kinds of angles and do it smoothly without serious wear.  I'm also working on just how to tie the engine and driven unit together so that one doesn't flip the other.  Also, the CV joint is semi-enclosed, not open like a U-Joint and shouldn't beat everything to death if it fails, as long as you don't let it run on without shutting it down. 
  One possibility is to mount the engine into a Cushman Truckster I have and install a side or rear PTO that couild be used to drive the different units.  Hence the driveshaft idea.  We used to use the ribber/urethane spider tyoe couplings at work, but, they too will eat the spider if not aligned pretty well (not perfect, just well).  Although they are not out of the running by any means. 

Swedgmon, Firebrick:  The information you gave on the different types of CV Joints and other couplings is great. It gives me a direction to do more research. I saw a co-worker, 'maintenance supervisor', use a 1/2" cold chisel as a shaftshearkey to try to get a piece of equipment turning.  Still gives me shivers when I think about it.

I also am looking at adding an intermediary shaft with another set of flywheels to damp out pulsing to some degree.

 One thing I'm looking for here is maximum flexibility in power transfer to multiple driven units.  Running a semi-permanent mount generator with electric motors on each unit isn't out of the question, just exploring other possibilities.
Lister Petter AC1, Listeroid 12/1, Briggs & Stratton ZZ, various US Mil. surplus engines. Crosley (American) 4cyl marine engine(26hp).

Firebrick

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Re: auto CV joints for direct drive gen.
« Reply #10 on: May 29, 2006, 10:54:26 PM »
Allright, from my experience the only place I would want a cv joint compared to a u joint is a generator because the difference in slowing/speeding up if both joints are not at the same angle, all the other equipment it should be no concern.  Here is why, 1st as you stated u joints are easy to change and are cheap.  Second while not impossible to do u joints will be much easier to adapt and cost less(every thing should be on the shelf at you local tractor/implement/Tractor supply store ect...)
The life might be slightly longer with a CV joint but they normally eat up the rubber boots that protect them around the same time as a u joint needs changed.  Much harder to do and you might as well rebuild the joint while your at it even if you really dont need to just yet.  Most cv shafts slip or move in the joint slightly but dont have a slip section to lenthen/shorten in your application, some do,  again look for the farm shafts(1000rpm) not the automotive shafts.  CV joints in our haybines and batwing mower lasted about 1800 hours as close as my dad and I could figure, lower that for higher rpm/ smaller shafts. 

Hope that helps

GuyFawkes

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Re: auto CV joints for direct drive gen.
« Reply #11 on: May 29, 2006, 11:08:57 PM »
boat owners have been solving this one for years





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Original Lister CS 6/1 Start-o-matic 2.5 Kw (radiator conversion)
3Kw 130 VDC Dynamo to be added. (compressor + hyd pump)
Original Lister D, megasquirt multifuel project, compressor and truck alternator.
Current status - project / standby, Fuel, good old pump diesel.

bitsnpieces1

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Re: auto CV joints for direct drive gen.
« Reply #12 on: May 30, 2006, 12:36:59 AM »
 Firebrick:      I wasn't aware that CV joints were used in farm implements.  But, your experience with them will get me to check them out.  The tractor ones would be better than auto.  Also, I had thought about the slip section, I just hadn't figured out how to handle it. 

GuyFawkes:    The first (white one) looks good.  The red one, I'll have to checkout.  We used to use similar ones but they would tend to degrade from heat and torque.  Of course that's with anywhere from 5hp 3ph to 150hp 3ph electric motors at 1750 - 3400 rpm and our particular maintenance system.  The slow speed low hp Listeroids might do allright.  As for the third one, How much angular misalignment can they handle? 

  At any rate THANKS EVERYONE  for some great ideas.  I'll be checking them out. 
Lister Petter AC1, Listeroid 12/1, Briggs & Stratton ZZ, various US Mil. surplus engines. Crosley (American) 4cyl marine engine(26hp).