Today's Message Index:
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1. 06:50 AM - Re: Landing gear electric actuator circuit (user9253)
2. 10:02 AM - Re: Re: Landing gear electric actuator circuit (Robert L. Nuckolls, III)
3. 11:19 AM - Re: Landing gear electric actuator circuit (user9253)
4. 04:54 PM - Re: Re: Landing gear electric actuator circuit (Robert L. Nuckolls, III)
5. 04:56 PM - Re: Re: Landing gear electric actuator circuit (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: Landing gear electric actuator circuit |
Below is a circuit to lower or raise a landing gear or to control the direction
of any small PM DC motor.
The toggle switch controls the motor direction of rotation.
The relay turns the motor on and off.
The limit switches open the relay circuit at end of travel, thus stopping the motor.
Diodes across limit switches allow the current to reverse direction when a limit
switch is open.
On the right side, there is an optional emergency switch to lower the gear.
Back to back zener diodes across the relay coil limit inductive voltage spikes.
Disclaimer: The circuit has not yet been proven to work.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=487972#487972
Attachments:
http://forums.matronics.com//files/long_ez_gear_423.jpg
Message 2
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| Subject: | Re: Landing gear electric actuator circuit |
At 08:50 AM 3/8/2019, you wrote:
>
>Below is a circuit to lower or raise a landing gear or to control
>the direction of any small PM DC motor.
>The toggle switch controls the motor direction of rotation.
>The relay turns the motor on and off.
>The limit switches open the relay circuit at end of travel, thus
>stopping the motor.
>Diodes across limit switches allow the current to reverse direction
>when a limit switch is open.
>On the right side, there is an optional emergency switch to lower the gear.
>Back to back zener diodes across the relay coil limit inductive
>voltage spikes.
>Disclaimer: The circuit has not yet been proven to work.
This configuration does not place a hard
short across the motor in the de-energized
condition. This may not be important if
stored kinetic energy on the motor does not
produce an unsatisfactory over-shoot.
Bob . . .
Message 3
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| Subject: | Re: Landing gear electric actuator circuit |
How about this?
Is the purpose of shorting the motor to bring it to stop it quicker?
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=487975#487975
Attachments:
http://forums.matronics.com//files/long_ez_gear_d_919.jpg
Message 4
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| Subject: | Re: Landing gear electric actuator circuit |
>
>Disclaimer: The circuit has not yet been proven to work.
This configuration does not place a hard
short across the motor in the de-energized
condition. This may not be important if
stored kinetic energy on the motor does not
produce an unsatisfactory over-shoot.
This is the advantage of using the spdt
relays to control motor power and
controlling relays through the panel
and limit switches.
http://www.aeroelectric.com/PPS/Flight/Flaps/Flaps_4.pdf
Emacs!
When the energized power relay relaxes,
it throws a dead short on the PM motor.
Back EMF generated in the motor produces
a significant retarding force to the
motor armature.
The nice thing about this configuration
is that dynamic braking occurs whether
motion command is removed by the panel
control switch -OR- a limit switch.
I've been pondering the notion of adding
a 'back up' circuit to supply down-stroke
power to the motor.
Every gear extension system I've encountered
on TC aircraft had a back-up . . . but in
EVERY case, the back-up mechanism was
NON-electric. Some were quite simple and
convenient (Beech Sierra - open valve
in front of pilot's seat. Gear falls and
locks). Some were not so convenient (Beech
Bonanza - Slide pilot's seat all the way
back, passenger seat all the way forward.
Fly left handed while opening door under
passenger seat. Extend handle and put
some rotations on the crank until 'three
greens' are showing. I think it took over
100 revolutions).
The important feature is that normal and
emergency extension systems do not share
any required commodity . . . like electricity.
The gear was MOST likely to fail do to
loss of motor . . . except in the Bonanza
which had a dynamic braking control contactor
with a rather Rube-Goldbergish design.
Bob . . .
Message 5
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| Subject: | Re: Landing gear electric actuator circuit |
At 01:19 PM 3/8/2019, you wrote:
>
>How about this?
>Is the purpose of shorting the motor to bring it to stop it quicker?
>
>--------
>Joe Gores
>
>Attachments:
>
>http://forums.matronics.com//files/long_ez_gear_d_919.jpg
>
Not bad! The only downside I see here
is that the crew control switch carries
motor current . . . which is not a
horrible thing to contemplate.
Bob . . .
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