Hyd prerotator and VW crankshaft PTO...how to join with an electric clutch

[magilla]

Hey folks,

the VW has electronic ignition, so I have the rear crank available for a PTO to use with the Hydraulic Prerotator.

Just have to figure out a way to join the two. My hyd pump is not rated for continuous duty,either....

So I have two options -

1) Use an electric clutch to engage the PTO directly to the hyd prerotator shaft. (preferred method)

2) Find a continuous duty hyd pump, leave it in bypass except when I pre-rotate. Use simple mechanical twist to engage/disengage the hyd pre-rotator

Both options seem pretty simple, as far as Murphy goes, but I prefer option 1 because it doesn't drag on the engine and steal HP, as a constant-running hyd pump would be.

Any thoughts???

Thanks!!

[Brent_Brown]

I would use COA 1.

[GyroRon]

Electric pre rotator.........

[magilla]

Seriously,

I would like to keep the setup I already have, and figure out a way to join the flywheel to the hydraulic pump. Most likely a pulley setup will work best. Planning on using an AC auto clutch or mower electric clutch on the pulley mounted to the hydraulic pump...

(can you give me a deal on an electric clutch from one of your mowers??)

However, if that doesn't work, and I have to buy a new continuous duty hydraulic pump, then I might want to look at the electric pre-rotator option.

Couple of questions:

1) Do I need a full size car battery? HUGE weight penalty, as I have a motorcycle battery now...might be offset by loss of hydraulic pumps, but it'll be close.

2) Who makes an electric pre-rotator for the RFD head?

2) How much?

Thanks.

[MikeBoyette]

Spencer,
Why not just go ahead and use the exact same set up that Joe used. Why try to reinvent the wheel? IT seemed to work fine the way he had it before.
Are you not using the same engine set up?

[magilla]

Mike,

I was planning on using the same set-up, but the Valley Engineering VW engine I now have has the dual coil ignition on top of the case, as well as the carbs and intake.

There is no way to make the original system mount up, unfortunately.

However, I do have 9 inches of clearance at the back of the engine, and free access to the crankshaft/flywheel. And a big hole where the magneto would go.

It just seems like the perfect way to use the hydraulic prerotator.

Just need to mate the splined driveshaft to an electric clutch, and then to the hyd pump.

I am NOT a fan of doing things the hard way...:lie:

Well, sometimes. But in this case, I have no idea what i'm doing....

Did I say that right?

[Ron E]

Spencer,

What about an electric pre-rotator system that is powered by a high-Amp belt-driven alternator which feeds power to the electric motor that will turn the rotor? No extra-large battery required. When not pre-rotating, the power from the alternator could be used to power other electric devices. May have to have a diode and a capacitor in the power circuit to protect the alternator from spikes.

Use flexible, multi-standed welding cable to feed the pre-rotator motor. It can carry more amps than the same gauge "battery cable" type wire.

Just an "electric" idea that I am considering.

[GyroRon]

Spencer, you need to find out what type of starter will mesh with the ring gear on the rotor head, then buy that type starter. Then take the rotorhead and starter to any good machine shop and have them mate the two pieces.

A electric prerotator will work fine off a motorcycle battery.... yes it work work better with a larger battery, but a small motorcycle one will do the job.

I have nothing against hydro pre rotators, but they are not light.... and by the time you figure out a way to install it to your engine it will be a very heavy system.

The electric pre rotator system can be bought for less than 200$ total including starter and all cables and switches etc.... It is simple, cheap and easy and works just fine.

Don't loose sight that you got a already heavy gyro, and every pound you can shed is going to help your gyro fly better.

[Timchick]

Could you attach a flywheel of some sort and use a Wunderlich setup similar to the photo below? How far away is your mast from the rear of the engine? Maybe the drive wheel could press against the other side of the flywheel and then go up to the rotorhead.

[WHY]

Hi Spencer

Have you looked at how the hyd-pre rotor drive is done on Andy's "Woodstock"

Tony

[magilla]

"Don't loose sight that you got a already heavy gyro, and every pound you can shed is going to help your gyro fly better."

I need to go on a diet... This is depressing.

I'm looking at a bloody shaft that can be mounted directly to a crankshaft, and all I need to do is figure out how to mate the two shafts...and then make it engage when I want it to...

I've been looking at PTO clutches...like for mowers and hydraulic systems, but the smallest I've found is 9 pounds.

I'll count the number of teeth on the ring gear tomorrow...I have the RFD head, ring gear, and RFD hydro prerotator set-up.

I really like that wunderlich set-up, too. Looks muy simple, and light.

Will take pics tomorrow.

Thanks for the replies. There's gotta be a way!!!

[Brent_Brown]

I was going to say use a wheel on the pump and use it like that. I was looking at doing this on the corvair. much lighter than the e-clutch

[magilla]

Thanks, Brent...

Basically, put a wunderlich rubber wheel on the hydro pump shaft, and then engage manually... Now to figure a bracket....

I have a 3 inch prop extension, so I have three inches available on the top of the redrive..

I also just found a deal on Ogura and Pitts e-clutches used on auto a/c compressors...they only weigh 3 lbs, and are exactly what I want. Cheap from the boneyard, too...

Hmmmmmm......

[dragonflyerthom]

Spencer

Is your prop coming off the front or back of your engine? Waiting for pictures before commenting any further.

[scottessex]

Someone that has a Little wing could tell you what e starter fits a RFD head,
Why can't you use a belt and manualy engaged idler pully?
Will an electric clutch allow enough slippage?

[Brent_Brown]

I was thinking use the wheel on the back or flywheel side out of the way and all, shorter hoses less weight.

[dragonflyerthom]

My thoughts exactly Brent.

[Dean_Dolph]

...However, I do have 9 inches of clearance at the back of the engine, and free access to the crankshaft/flywheel........Spencer, I've always been a fan of the prerotator design that Dave DeWinter used on his Dominator Suburu. It is a derivative of the one that Catfish Oxnam uses on his Soma Suburu. I don't know if 9" is enough room to use this prerotator but I suspect it is.

I believe Dave's used a one piece 8" drive wheel while Catfish's had a 10" multi piece wheel. It is my understanding that Catfish could get right at 300 RPM out of his but he had to be careful during engagement because it wanted to grab. There were also some clearance problems as I recall with the water pump or something in the vacinity. I don't believe Dave had the grabbing problem. I don't know what RPM Dave was able to get with the smaller drive wheel.

You can see from the pix that the drive wheel is beveled so it matches up with the driven wheel as it is swung into contact position. You can also see that the driven wheel is connected to a slip joint two piece square drive shaft with universal joints at each end. I don't recall the details at the top where the bendix is and the pix doesn't supply enough detail.

I wish I had detail pix of Dick DeGraw's prerotator on Carol's Dominator. It sets at the front of the engine also and looks like it incorporates a cone clutch. Neat setup! I'll look for the pix I think I have of this device and post them if you are interested.

[magilla]

Hmmm....

That looks to be the way to go....

Saves weight, and looks simple.

I will post pics tomorrow...

[magilla]

Decided to chunk the hydro rerotator in favor of the e-version for the RFD head.

1) mating the vw flywheel to the hydro pump shaft would have been too difficult, and weight is becoming a factor.

2) the wunderlich system from engine flywheel to rotor looks good, but I would have to work it from the back of the engine, 4 ft back to the mast, and then 5 feet up to the rotor system. would have had to have a 90 degree gearbox or about three extra u-joints.

3) I was thinking about pilot controls...brakes on, throttle forward, engage hydro rotator with other hand, manipulate speed with throttle and hope you don't lurch forward. I like the idea of having a pre-rotator work off of a separate switch, and engine rpm doesn't have to be full bore...


Ring gear has 109 teeth.

Anybody have plans for an e-pre-rotator with soft start?

[CLS447]

A friend of mine,Parke Hoover, who is a member here , has one on his Tandem Air Command.

I am very impressed with how well it works. When he kicks in the second "phase" ,man do his DW's take off !

It works very well for him. Maybe he will post some info for you...Parke ?

[Timchick]

Try these links:

http://www.rotaryforum.com/forum/showthread.php?t=9294

http://www.rotaryforum.com/forum/showthread.php?t=6767