cobrajocky

I just received a bunch of 3.7g Servo-less Retract Landing Gears from, where else, China. These are pretty high quality, rebuildable, metal gears, metal strut block. I'd like to test them in a simple way just for operation - opening / closing repeatedly - before installing them. I'm pretty new to servoless retracts, always used servo or air-operating retracts.

Looking for suggestions on how to set up a "test rig" without using a transmitter to test them without damaging or burning them up. I have a 3 Mode Servo Driver / Tester (see picture) that has 1) Manual mode, 2) Auto Neutral centering, and 3) Auto Continuous Cycle (rotation) mode. This Servo Driver connects to an ESC and then to a LiPO for power.

I would like to test full extension to retract, lock up and cycle the retracts (open / close) to filter out the flakey ones, if there are any.

Any solid suggestions appreciated.
Thanks

chuckk2

The problem is that the servo less retracts have a duty cycle limit which is likely unknown.
Details
To drive the retracts, you will need two different pulse trains, one with a pulse width of about 1000 to ~1200us, and one with a pulse width of 1800-2000us,
or depending upon the retracts exact method of operation one pulse width of below ~ 1500us, and one above.
A servo tester may or may not be able to do what you want. One of mine (generic yellow box) will come close, but is not easy to set up.

When setup properly, the knob controls the rate that the tester switches from one pulse width to the other.
If the retract works with a greater than less than 1500us scheme, a servo tester set to a very slow sweep might work.

cobrajocky

Chuckk2 -

Thanks for the very detailed info. I knew roughly, far less details than you provided, about the duty cycle existance in regular separate retract servos, but not knowing if that would apply to servo-less electric retracts. Though I suspect that so-called servo-less retracts are really just a combined servo IN a gear-driven mechanical retract package. Is that true?

My modest Servo Driver / Tester has no adjustment for the 3rd position "Cycling mode"; it just sweeps at a factory set rate. The 2nd mode (centering) is also a set position. The 1st mode, manual is the only mode that the knob controls where the servo position is. When you first apply power to the Servo Driver / Tester, it defaults to the 1st mode - manual.

You don't think just using the Servo Driver / Tester in Manual or any of the modes has any chance of "Burning up" the retracts, if I'm experimenting?

Maybe I'm just going to have to do a Tx /Rx setup to test these afterall?

Thanks for your insight and experience.

cobrajocky

Just an update, tried the Servo Driver / Tester I have and did not work to drive the eRetracts in any mode. Still looking for options.
Thanks