Progress on the throttle

2

28. October 2015 by Peter

Another thing that I have been spending time on the last month is my attempt to build my own throttle. It all started over 2 years ago when I all of a sudden juggled the jigsaw and ended up with the 11 plates for a DIY TQ. And so they have been laying around untouched for over two years…

But now things are moving! And moving rather fast.

So I have used August and September on the throttle handles and they have come out quite okay. The video below shows what I have done.

A special thanks goes out to Sven-Erik Arneberg who have been a huge inspiration for the motorization of the throttle levers. He has also helped me interfacing the servos with Prosim737. The link is to the facebook-group “Simgruppa” a cockpit building site. If you now are a member yet, you should head over there right now. You can get a lot of help from this group and fast.

So there are a few things that I have done in my build that might be of inspiration to you:

Skærmbillede 2015-10-27 kl. 10.33.50The reverser handles have been fitted with small 10k pots instead of microswitches. This allows for the reverse thrust to be applied according to the position of the handle and not just more/less depending on whigs microswitch is engaged. You could say: the handle has has a function in all its movement.

I was lucky enough to try a real B737 throttle a few weeks ago. And there is a huge difference between what I am making and the realthing.The reverser handle is locked unless the throttle is in idle. Then you move the reverser handle halv way up to arm the reverser and only from half way and up is where you apply the reverse thrust. Furthermore I have installed rubberbands on my handles so they return to idle. On the real thing the reverser handles keeps their position.

Skærmbillede 2015-10-27 kl. 10.34.50In order to apply pressure on the handle it self – to make it a bit harder to move I have used the kind of fabric that you put under your furniture to prevent it from scratching the floor. The grey fabric that I use is from IKEA. So the idea is that the handle is so tight on the axis that it presses a bit on to the fabric creating a sort of resistance when the handle is moved.

Skærmbillede 2015-10-27 kl. 10.35.27I use 10K sliding potentiometers to measure the position of the throttle handle. This is easily done by connecting the handle to the pot via an arm. This way I do not have to install gears and the resolution will be better because of a longer travel with the slide pot compared to the normal turning potentiometer. These were the longest I could find. To get the correct length of travel you need to adjust the position of the arm om the throttle handle.

Skærmbillede 2015-10-27 kl. 10.34.25Inspired by Sven-Erik Arnsberg I have attached heavy duty servos to throttle arms If this works it will allow for Prosim to move the handles when the A/T (Auto throttle) is engaged in a mode. That is what you call a motorized throttle. 🙂 The servo also gives a nice feel the the handles when moving them with no power on the servo. You need to adjust the position of the horisontal arm to get the right movement of the arm compared to the travel of the servo-arm. it takes a few try before you get it right (Hence all the holes in all three pieces.

The Fuel cutoff is pretty strait forward. However I have placed the microswitches so that the switch only is engaged when the handle is released / locked. You cen see in the video how this is done.

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2 thoughts on “Progress on the throttle

  1. Hi Peter,

    I am in the process of making my home built Throttle Stand. I found your videos and site very helpful in the process.

    I am doing everything in 3D with Sketchup first. I have based my Throttle stand measurements from various sites and images, as the drawings from http://www.737ngproject.be/throttle.htm is not correct when compared to the real. Doing this I am able to verify all dimensions etc before actully making the hardware.

    I am planning to make it all motorized and found your solution quite good.

    An issue I have not any solution for yet, is the handling of the thrust levers that is going to be hooked up to servos. If there is power on the servoes when trying to move the levers it will break the servo motors. This means that the power to the servos has to be cut off prior to the movements( when the Aotuthrolle is disabled). That I think I can manage, but if I accidentally move the levers when AutoThrottle in activated it will burn. It means that I have to have some sort of mechanical solution that prevents the manual movements, but not the automatical movements.

    Have you thought about this and found a solution?

    cheers,

    Roar

    rksoftware

    http://www.flightsim4fun.com

    • Peter says:

      Hi Roar.
      I am using a servo, that is a bit more heavy duty than the regular. They do not easily move. In fact you need to apply quite a lot of force to move them.
      I have not succeeded in interfacing the servos to the 737 yet (OpenCockpits problems). But my plan is to use the A/T Disconnect buttons on the throttle to allow manual movement. When the A/T is disconnected Prosim should send a “0” (Null) to the servo which powers it down thus allowing it to be moved.
      If you have more precise drawings of the throttle I think the pit-building community would love to see them as the 737ngproject.be drawings seems to be what everyone is using.
      Cheers
      Peter

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