Real 727/737 throttle conversion

[Rodney]

I am looking for input on converting my 727 throttle. There is approx. 7" total throw with reverse so I do not think a 100 mm slider will work at all. I have tried using the pulleys with a pot attached and while it does work, I don't think it is the best setup. So I'm looking to see what others did when the configured their real throttles. Thanks in advance.

OBTW sting pots are too expenxive and out of my budget.

[Gallie]

Rodney,

I own a 737 quad. And have been finding a good solution too. Unfortunately stringpots are the way. I know they are too expensive. But it is the easyest way for getting throttle + reverse on 1 single potmeter.
I whas lucky to get one from Rob "737NUT", and must say that they work like a charm!
The stringpots are made by Unimeasure. I found a supplier and they dont come cheap. est 185 usd each

this is how i converted mine:

throttle force: put a thin layer of rubber sheet under the old dust covers, by removing the plastic strips beneath them and replacing them with rubber.

Throttles: 10inch stringpots from unimeasure 1Kohm

flaps: 100mm slidepot

speedbrake: 100mm slidepot + servo for automation

trimindication: 1 servo

trim wheels: i contacted simparts.de for a chain + chainwheel solution.

park brake: going to use a micro switch with solenoid (type 25ET11 found on ebay)

Good luck. Im working on this project for almost 1,5 years now.

Mike

[Michael Carter]

100mm slide pots will work. The linkage just needs to be figured.

[Rodney]

Thanks for the information Mike!

I would only go string pots as an absolute last resort. Great thing is I work with with a group of electrical and mechanical enineers in a R&D company so I may just let them give me some direction too. What ever the outcome, i'l sure post it as I am sure I won't be the last to do this.

[Rodney]

100mm slide pots will work. The linkage just needs to be figured.


Mike,
No linkage. There are cables for the throttles. The only linkage is on the spoiler and the parking brake which I think a slider will work on. Just haven't got there yet. I guess a picture would show it better. I'll post one tonight after work.

[Gallie]

Rodney,

What the other Mike means is, you can drill a hole in de metal wheel of the throttle or in that plastic thing attatched to the wheel. To connect the linkage to your 100mm slide pot.

Mike

[Michael Carter]

That's what I mean. I know what the guts of these older throttles look like.

You'll need to figure out how far in from the circumference of the cable wheel to drill the hole for the linkage to the slide pot to get 100mm throw, and then decide where to mount it.

If you can't get 100mm throw on the very outer circumference of the cable pulley, you could add a short arm to the edge of the wheel in a convenient location to increase the travel.

Swivel ball joints and connecting rods are what I used to connect mine. Probably a little overkill for the stress it's under, but it'll never fail.

[Rodney]

I think I can picture what you are saying. In order to do that I would need to completely disassemble the quad. I had not planned on doing that ........ yet.

[Michael Carter]

You really should anyway just to clean out the 40 years of dirt, crud, and cobwebs if for nothing else.

At the least, you'll understand how these throttles work and how they're built.

As large as these pulleys are, you should have no trouble getting 100mm throw from full forward and aft movement of the throttle levers. Even if you can get only 85mm or 90mm, it's still better than 60mm.

[LH784]

Dear Rodney,

here is the plan of what I want to do with my TQ. Instead of taking my TQ apart (I am afraid, I am a bit technically challenged, but still I am sure I will be able to finish the project in the end :)) I will expand the cables / wires from the TQ and put them over a wheel / roll to whick I will attach a normal rotary pot. It's not my idea but I got the idea from Bernd Drefahl's site (with his sim it works) and I have drawn what I intend to do.
I guess, this way of doing it should be technically least demanding and also least aggressive to the original parts (Mike, I know, you really love the 727 and it's parts, but I would not like to drill holes into any part if it can be avaoided :-)).

[dnoize]

You really should anyway just to clean out the 40 years of dirt, crud, and cobwebs if for nothing else.

At the least, you'll understand how these throttles work and how they're built.

As large as these pulleys are, you should have no trouble getting 100mm throw from full forward and aft movement of the throttle levers. Even if you can get only 85mm or 90mm, it's still better than 60mm.


The problem is that its much more than 100 mm...

more in the 200 range...

[Michael Carter]

That's even better. No extension bar would be needed, only a calculation of how far in to drill the hole for the linkage rod and ball joint.

[Rodney]

Stef,
Have you completed yours yet? My orginal design is like florian's with a cable and pulleys. I was going to use the fuel cutoff pulleys (not the actual wheel, the pulleys that routed the cables below) but there is no room to put a nut on the pot, so I will build brackets and test that method.

[dnoize]

Currently working on it with mike (gallie here) who has the same throttle.

Stef

[Rodney]

I got the pots installed on the throttles and flaps and they work just fine. Its a bear getting the throttles reverser calibrated right, but I will get it. Now to figure out what I'm going to do for the spoiler. The fuel cutoff switches, trim switch, parking brake, and other lights should be easy (or maybe they won't be as easy as I envision them to be). I've already removed the outer bracket for throttle #1. I built one for each but they aren't needed.

[Gallie]

Rodney,

This is what i did with my speedbrake:
http://www.mycockpit.org/forums/showthread.php?t=12495

I just rewired the original fuel switches inside the quad.

It looks like youve found a cheap and good way to get the throttles interfaced. Well done.

Mike

[Rodney]

Thanks Mike. I was thinking along the lines of doing away with the tube and moving the pot inside the throttle. I am going to tackle that next week when I'm off.