Hydraulic Prerotator

Crash

Newbie
Joined
May 7, 2010
Messages
7
Location
Mackay Queensland Australia
I've been searching the threads for ideas on hydraulic prerotators.
Are there any proven systems out there that we don't have to buy from a gyro manufacturer?
Or does anyone know what size/model pumps and motors they use?
I was thinking of using the power steering pump off the motor, with an electric clutch installed, and using the same size pump as the motor with a bendix installed. Has anyone tried this?
I am using a EJ22 with an autoflight reduction.
Thoughts
Regards
Crash
 
Hi Crash
If you do a search for "hydraulic" there are 3 threads that I know have discussed this because I took part in them, there may be others that I don't know about or have forgotten
Look at threads "Magni M24 Orion the report", "Hydraulic pre rotator specification" and "New heart for the predator". There are some performance curves for pumps and motors that I posted that may help you get started.
Good luck
Mike G
 
hydraulic prerotator

hydraulic prerotator

a power steering pump is not going to be able to provide enough volume for a prerotator.
 
Thanks Mike,
There is a lot of information contained in those threads.:eek:
Makes it easy to build once you eliminate the unknown/variables such as the size/model of the pump and motor.
Even found the model bendix that are being used/converted.
I'm still reading the threads for an indication of electric clutch usage on the pump. The concensous seems to be for a belt drive with a tensioning mechanism for engagement.
Now I've discovered the search mechanism :der:I also punched in jump start. There seems to be a lot of discussion regarding this but no real concrete idea's. The jump start option would be great in Aus as we have a real lack of prepared area's in the bush, suitable for even short takeoff's.
If you know of any threads that have any real information in this regard, they would be most appreciated.
Regards
Bill
 
Northern Tool has a great selection on pumps and motors. The bendix on the other hand would require a lot of machine work, or just buy that part from the manufactuer.
 
Here you go.(Parker)/ Pump,,,,, PL-08649 MGG20025 BA1A3
(Parker)/Motor,,,,,X1007 C3086 MGG20020 BA1A3

Both Made In Mex.

I got the info right off of a Domanator.... Contact Granger or Google
 
Hey Blokes,

Thanks for the replies.
I found all I need in the following thread with the information on Post 5 and 11 the most helpfull. http://www.rotaryforum.com/forum/showthread.php?t=25202&highlight=hydraulic

I've tracked down the pump/motor from surplus center and the bendix from airsuppliers.com.
All at reasonable prices (if the Aussie dollar comes back up again).

Only thing I am still trying to get info/tech help is the use of an electric clutch for the pump. Has it been done successfully?

Thanks again.
Bill
 
A/C Clutch for Hydraulic Pre-Rotator

A/C Clutch for Hydraulic Pre-Rotator

Both BillyGyro and I have used A/C clutches with good success on our hydraulic pre-rotators. The clutch is connected to the shaft of a hydraulic pump. No complaints. This is the setup for my 2 place. It uses an EJ-22 Subaru engine.
 

Attachments

  • clutch1.jpg
    clutch1.jpg
    136.3 KB · Views: 6
  • clutch2.jpg
    clutch2.jpg
    126.9 KB · Views: 6
  • clutch3.jpg
    clutch3.jpg
    141.6 KB · Views: 5
  • clutch4.jpg
    clutch4.jpg
    137.8 KB · Views: 5
Mate,
That looks good.
By the look of the photo you used the original A/C compressor and just removed the innner workings etc to allow room for the pump on the original mounting?
Is this right?
Would make the installation easy as the belts/pulleys etc would be already aligned and off the shelf subie belts would do the job.
Have you any control over the flow to the prerotator motor apart from the clutch and engine speed?
I was going to put a manual control bypass valve in a tee piece (parrallel to the relief valve) between the pump and the motor and use this to soft start the prerotator motor and unload the clutch on engagement. Is this necessary? I see some prerotators on youtube that really twist the mast on start up. (Makes me nervous to see those extra forces at work)

Are you using the pump/motor as descibed by Billgyro?

What size dendix and ring gear are you using?

What rotor rpm are you getting out of this arrangement?

Thanks for the info BillyGyro and Jon. Makes life a bit easier by not trying to reinvent the wheel !!

Regards Bill
 
Crash
I doubt if you need to "soft start" the pump. The electric clutch is a nice idea, I'd be curious to know the weight.

I'd also like to know more about how you got the bendix.

Mike G
 
Hey Mike,
I used the information from the "Hydraulic pre rotator specification" thread you put me onto.
The airsuppliers and the bendix number are on post page 11.
I haven't bought the unit (around US$100) yet but they have them in stock.

The same as the pumps and motors from the surplus centre (Post 6), in stock and less than US$200 each.

There are some good idea's starting to flow and I'm impressed with the use of the air con compressor conversion for the pump mount. Being alloy it wouldn't weigh much.

Jons photo's are impressive and I can see a very neat set up about to come together.

Regards Bill
 
Crash, Most of what I have read on hyd prerotators they use an "open center" system. The hyd fluid just goes around in circles until you port it to your motor. In this type system the hyd fluid tends to heat up and a small amount of power is lost even when not engaged. You would also need some way to cool the hyd fluid. John K.
 
I get about 120 RRPM out of my setup. Soft start isn't really required, but I do hit the engage button intermittently for a few times at low engine RPM before I get serious about the spin-up just to get things moving. It uses the front half of the A/C compressor shell for connectivity and use of the original bearing. The weight is about equal to a belt-tensioning system.

This method does NOT use the perpetual pump and bypass method, so no cooling is necessary. When it is off, it is off.

My unit uses the ring gear from a 75HP Mercury outboard and the same pump BillyGyro mentioned. The bendix is a stock unit from an auto-parts store and attaches to the hydraulic motor at the rotorhead via a shaft collar in much the same way the shaft of the clutch attaches to the pump.

You will have to build a small oil tank for supply and recovery. I use hydraulic jack oil. I thnk Billy used some kind of transmission fluid. Both worked well.
 
Crash
Thanks for the heads up I'd missed that.
Good luck with your system.

Mike G
 
Is the Wunderlich Bendix and ring gear suitable
for a Hydraulic Prerotator.
Has anybody got an A/C Clutch setup an EA-81, do you use
a standard EA-81 A/C setup, are they strong enough?


Cheers Mick
 
Hey Mick,

Give Mad Max (over at Mandorah, Asra Instructor) a call. He may be able to help with the engineering for removing the compressor and setting up the clutch.
Most A/C use about the same power input so I can't see the diff between the EA81-EJ22 series of engines/compressors. Looking at what the boys (Billy & Jon) have done, I think it may be a matter of the quality of the engineering that will make the difference.

I may be wrong but it's gotta be close.

Regards
Crash
 
If you read the post before it states 120rrpm, you can get that from a electric one, i done all the testing ect a couple of years ago set it all up ect ect, the clutch cant hold the pressure for a decent prespin. Yeah i wanted it to work too for all the reasons above, but unless you can find a clutch with the holding power of super glue, it wont work.
I use a RAF prerotator, and with a good long handle and me hanging on for dear life, it will still slip once you start to get towards 200, nd once you get towards 300, there is slipping going on everywhere, there is alot of pressure required to keep the clutch engaged.
It all depends on what speed your after, for anything around 120-150, just use electric, simplier and easier to set up.

The mongrel im building now, will have a hyd spinning but a very different type of engagement, hope it works, will put pics up when its finished, but i need to get home from the NT then finish in the gulf, then i might some time to get back to it.
 
Last edited:
Is the Wunderlich Bendix and ring gear suitable
for a Hydraulic Prerotator.
Has anybody got an A/C Clutch setup an EA-81, do you use
a standard EA-81 A/C setup, are they strong enough?


Cheers Mick
Why not just use the whole system from Tom? lighter and easier
 
75 foot pounds

75 foot pounds

We were going to drive my hydraulic pump off the accessory drive on a Lycoming and have it run all the time.

The drive is overdriven by 30% and the pump had to be good to 3,510 rpm.

We were going to machine an adapter because a big enough pump wouldn’t bolt to the mounts for the vacuum pump.

The valves got a little complicated and heavy.

Since two nights ago we are looking at using an electric clutch and driving it off the pulley for the air conditioner on the propeller end of the engine.

We found a $70 electric clutch at Surplus Center that is good for 75 FOOT POUNDS of torque.

That would suggest to me it can manage slightly less than 50 horsepower at 3,500 rpm.

The pump system is only good for about 12 horsepower so in my opinion the clutch is plenty strong enough.

The clutch, pulley and bearing appears to weigh around 7 pounds.

This will allow us to use a larger pump and spin the rotor faster at a lower rpm.

I suspect that the weight savings in oil, lines, valves, gear and adapter will be close to the weight of the clutch.

I feel we will only need a pressure blow off valve to manage the start process.

We are a ways off from implementing this fantasy. It will be in the building Mariah Gale thread when we get around to it.

Thank you, Vance
 
Top