Slipclutch on ebay

[kurt-olsson]

http://m.ebay.com/itm/DYNATECT-POLYCLUTCH-SLIP-EASE-EAS-16-MECHANICAL-SLIP-CLUTCH-ADJUSTABLE-/301867246746?nav=SEARCH

Sorry for "spamming" the forum last days, but i found these on ebay.
Do you think these will work for the throttle motor and are they in the same spec as the polyclutch used among many here on the forum?

[FredK]

Looks to be an interesting find for the price.  It has multiple slip plates and appears to have adjustable torque.  Would need to know the torque range specs. Any detailed specs available?

Fred

[kurt-olsson]

This is what i found...

Buyer receives 1 New DYNATECT SLIP-EASE CLUTCH .

P0LYCLUTCH, ADJUSTABLE, EAS 16

BORE 2.50", O.A.L. 1.5" , OD 1" OUTPUT 3/16"

16 inch lb, watts 9

500 lb-in max

Watts=torque x RPM x Duty Cycle x 0.011

PLEASE CLICK ON THE PICTURES TO GET A LARGER MORE DETAILED VIEW OF THE ITEM.

We do our best to describe all items to the best of our ability.Please do not assume that accessories or the condition

is other than described in the description.Any questions please feel free to ask.

Sorry no international customers at this time except thru E bay global.

[jackpilot]

I have used polyclutches for years now in my TQ and they work flawlessly.



You can contact them directly , not Ebay
http://www.dynatect.com/polyclutch

[Flying_Fox]

Polyclutch  are the ones Rob installed in my converted TQ.  No problems with them. I did not even need to adjust them for about 3 years.

Nick

[FredK]

My slip clutches are also manufactured by Polyclutch.  Part # is S98CA6MMOC320838.  I sourced them from Sterling Instrument www.sdp-si.com.

The only comparable spec you defined is the power dissipation wattage. Your find is rated at 9 watts...my slip clutches are rated less than that at 6 watts.  The override force for my TQ feels about right.....although I have to say I have no experience with a TQ in an actual operating real 737. Your clutch would take more force to override. The part also looks to be a bit more heavy duty in that regard. I would be concerned about that given the light duty motors involved.

The price is an incredible find though.

My motors and slip clutches are working flawlessly to this point....about 2.5 years in service.

Fred K

[kurt-olsson]

hm...

3-4 people who have done great builds have the same clutches and are very pleased with the quality.

Maybe it is just being cheap to buy the ebays... they are like 20% heavier stuff both in size and spec.But if they would work aswell it would be amazing price... The Bore size is also rather large in diameter.

[kurt-olsson]

I think i will try two of them from ebay just for kicks.

Can anyone tell me if you can set the tension on your current clutches that you are using to reaaaaly low? or are they always some tention "default" that you only can increase?

[kurt-olsson]

Allright! I found a company in sweden that provides the sliipper clutches.

http://www.huco.com/products.asp?p=true&cat=347

I know that are one other on the forum that has the huco clutches.

[mickc]

I think i will try two of them from ebay just for kicks.

Can anyone tell me if you can set the tension on your current clutches that you are using to reaaaaly low? or are they always some tention "default" that you only can increase?

You can set the tension really low on both Huco/Dynatork and polyclutches, but you need some tension to overcome the resistance of the throttle handle mechanism.  if its too low it will start slipping while the motor is trying to move the handle.

[kurt-olsson]

I see, thanks for your input

[FredK]

Peter -

The thing that you need to understand about selecting a proper slip clutch is the concept of slip torque range.  Taking the Polyclutch product as an example.....Google for the PDF specification sheet associated with the part number that I defined here earlier.  That spec sheet actually tabulates several different slip clutch models according to operating torque range (and other considerations such as bore diameter etc.).  You will note that my particular slip clutch is at the lowest range.

Again...proper torque range is important.  On one hand you want your lever motors to be able to move the levers without slipping, and on the other hand you want to fairly easily be able to "break" or override the motor motion.  If you select a torque range too high it would take an abnormal significant force to override the lever motion....possibly even damaging the motor.

Most of the recommendations that you are hearing here are a result of "trial and error"....there are few if any of us here that are knowledgeable enough about physics to actually measure and define required torque and other factors.  So do benefit from the knowledge of those that have gone before you.  You will find that you will be doing a lot of trial and error anyway fitting the motors and pots etc. I can't say how many times I re-did things to get levers working properly etc.  But that is the fun of doing the build...there is a great satisfaction when you finally get the thing working for yourself.

On another point regarding lever motors.....My lever motors are nominally 15 rpm.  However I have them operating at the lowest possible speed which is probably half that (you can adjust speed via your SIOC script and motor card interface).  Lower than that there is not enough torque with my motors to move the levers.  If I had to do it over again I would have tried a 5 rpm spec motor in that regard.  My experience is that a lower speed is better to minimize "hunting".  That is what I observe within the speed range that my motors operate.  My theory is that hunting occurs because the physical motion of the lever is faster than the actual "commanded" rate of change defined by the sim program flight model. That is, the lever outpaces the commanded value and momentarily stops because of it.  If that logic holds true, then if you slow the motor speed so that it is always behind the commanded position there would be no stopping...or back-and-forth motion when the lever overruns its position. Again, that is what I observe within the operating range of my motors.

Videos of real throttle lever motion that I have seen also demonstrate a slow motion....so such may in fact be closer to reality as well.  I do have some minor hunting at times but frankly once I am flying I really do not at all notice it.  So I am not particularly bothered by it...however for others it may be an issue.  Replacing my motors with a 5 rpm model is on my list of things to do but is very low priority at this juncture.

Fred K

[Caflyt]

i bought those EXACT clutches from that EXACT supplier on eBay about a month ago.
I am in the process of re-engineering an older Simparts.de TQ (Thanks Joaquin) and have changed over from the servo driven setup it was designed with to a dc-motor driven system. I have installed the clutches and my initial tests have been very good.
These clutches seem great so far.
Here are 2 short videos of the tests.

(Sorry if the video quality is poor)

https://www.dropbox.com/s/ubeyj5dtuv7hryp/File%20Mar%2026%2C%204%2056%2055%20PM.mov?oref=e&n=449026281


https://www.dropbox.com/s/vtisaqseh6v5q41/File%20Mar%2026%2C%204%2051%2028%20PM.mov?dl=0

I will be starting another thread soon to document my progress on the complete conversion of this TQ but so far I have stripped it down completely and changed the throttle levers (the original levers were not to scale and actually cartoonishly large), flap and speed brake levers, flap gate, and fabricated two pulley systems for the A/T.

More to come soon.
Craig

[kurt-olsson]

Nice work catfly!

Now i see they don´t ship international, otherwise i would have likes to try them.

I agree with Fred, i will start small and gain experience in how it works.
Today i cannot see how the throttle woule be offsync but maybe i will get an understanding for it once i start wil the mounting.

I want 100% synced throttles, thats really important to me.

[Caflyt]

One word of caution though,
The bore sizes he has posted do not match up with anything on the actual item!!
The input side (next to the adjustment knob) was 6mm which was perfect for my motor shaft BUT the output side was smaller (about 4mm or so, can't remember) so I bored the output cap to 8mm to fit my shaft diameter. Thankfully it all worked out.

Fred, I copied your motor RPM's from your old posts (15 RPM) but now you think that's too fast??
Should I source a lower RPM motor before I get too much further in this process??
You think 5 RPM is more accurate??

[kurt-olsson]

I will try 6RPM!!! =)

http://www.electrokit.com/en/dcmotor-with-gearbox-612vdc-500-1-6rpm.51557

I am gona order these bad boys and give it a try!

I can live with slower movement if the sync is 100%

[FredK]

Craig and Peter...

As mentioned here and in an earlier tread I would strongly suggest going with a motor in the 5 rpm range. The caveat here is that my recommendation is based on a theory as opposed to something I actually have installed, but the following video repost I think will help make my point. This is a video of my TQ lever motion that I had posted earlier....

https://www.youtube.com/watch?v=KPF-UHSOye0

Note what you see in this video carefully.....First, the 15 rpm motors in this demonstration are actually running at near their slowest speed possible....I would guess somewhere in the range of 5-7 rpm. At this speed the lever motion speed appears realistic but probably is still (in my opinion) a bit faster than a real operating TQ (real 737 or other pilots please comment).  Also, watch the motion of the levers on the descent cycle carefully (this is the toughest sync case since it involves the full sweep of the levers).  In general you will see smooth motion for about 75% of the travel and then the levers stop momentarily and instantaneously resume. My theory based on watching the corresponding offset readings is that the position of the lever at that point has overrun the commanded value of where it should be and thus stops.  In at least one particular case you will see that the left lever very slightly outpaces the right lever and indeed is the first lever to momentarily stop....because it is ahead in the race.  My experience is that if I run the motors at a higher speed this "hunting" effect becomes more pronounced....so I have found that the slower is the better.  The thing is of course is that with my 15 rpms I cannot run any slower than where I am at.

I think the 6 rpm motor Peter has identified would be a very good choice!  But again...no guarantees since this is only theory from my side.  It would be breaking new ground here....I have not seen anyone here who has gone that low in rpm.  I would be very interested in knowing how it works.  Again, swapping in 5 rpm motors is on my "to do" list but is very low priority.

The following is another video repost demonstrating operation of my speed brakes....

https://www.youtube.com/watch?v=d6DtCHm1MMI

Fred K

[fordgt40]

Peter

Some suggestions

This link has the info on throttle lever speeds

http://www.cockpitbuilders.com/community/index.php?topic=4044.msg31192#msg31192

Presumably your levers will be driven by a chain and sprocket from a gear mounted on your motor/clutch shaft. If so, then I suggest you gear down the speed to match the maximum throttle lever speed, keeping the motor speed close to its optimum torque. The slower throttle lever speeds can be controlled by software.

I would also check the required torque to just move the lever from the full throttle position using a fisherman's spring balance, the pull force times the distance from the throttle axis to where you attach the balance will tell you the torque needed. The force needed can be surprising when pulling against the lever inertia and gravity. You do not want to select a motor that has the correct speed but insufficient torque

If you need info on the 737 design parameters for lever breakaway etc, then let me know

David

[FredK]

David -

Good reference!  I had forgotten about all the details of discussion that happened on this two years ago.

Fred K

[kurt-olsson]

I have ordered the motors and sprockets and chains etc, maybe i can have a demo up on youtube just for the movement without the stringpot controlling it from x-plane.

Need to find a place shere to get wires with a steel ball in the middle like the original first.

Sum up: i dont think you can prepare to much, like fred said this is an trial error quest to find something you like.

Concerning the speeds, i will let the model descide the speed. My plan is just to move the delta from target-current position with a maxvalue. The importance is that 6rpm is somewhere close to get the throttles full movement in 4.4sec. (Gearing can ofcourse help aswell)

[fordgt40]

If you fail to plan, then you plan to fail 

[fordgt40]

The importance is that 6rpm is somewhere close to get the throttles full movement in 4.4sec. (Gearing can ofcourse help aswell)

Peter

Gearing will be essential as that motor will drive your throttle levers from full to idle in only 1.66 secs. So, a 2.65 to 1 reduction gearing on your sprockets would seem about right.

Apologies if I am repeating your own calculations.

David

[kurt-olsson]

Thanks David.

I appreaciate your input, always nice to hear others thoughts aswell.
I ordered a sprocket that i think will have about 2.5 reduction. I will try to change speed aswell just for fun.

I am starting with the Conrad cheap slip-clutch. I will try get a good feel with it and upgrade if i feel the need for it.

Lots of questions and problems but thats the fun in this hobby!

[fordgt40]

Peter

That`s great, we are on the same wavelength! If you need any further info then just ask

Regards

David

[kurt-olsson]

sounds great!