Today's Message Index:
----------------------
1. 10:38 AM - Landing gear electric actuator circuit (jdubner)
2. 12:10 PM - Re: Landing gear electric actuator circuit (user9253)
3. 06:55 PM - Re: Landing gear electric actuator circuit (jdubner)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Landing gear electric actuator circuit |
My Long-EZ nose gear uses an electric actuator. The actuator does not have internal limit switches but I have added them and use them to control a pair of relays (see schematic: http://forums.matronics.com/files/nose_gear_actuator_108.pdf). (The electrical load is up to 10A -- too much for my limit switches -- hence the relays.)
I would like to incorporate a backup electrical extension system that would eliminate
any single point of failure (other than the actuator itself) and my attempt
is shown in the schematic. It's close, but not exactly failure-proof because
it adds the backup switch contacts as a single point of failure.
Can anyone suggest a better scheme?
--------
RV-8A
Independence, OR
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=487895#487895
Attachments:
http://forums.matronics.com//files/nose_gear_actuator_108.pdf
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Landing gear electric actuator circuit |
Those limit switches are suitable for 10 amps. No relays are necessary. A snap
action switch can easily carry the same DC current at 12 volts DC as it can at
125 volts AC, which is 15 amps in this case. This is true because the DC
voltage is only 1/10 of the AC voltage. If you do not believe it, ask Bob N. or
call Moujen USA and ask them what current the rating is at 12 VDC. Do not
tell them that you will put the switches in an airplane. If they ask, it is proprietary.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=487896#487896
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Landing gear electric actuator circuit |
user9253 wrote:
> ...call Moujen USA and ask them what current the rating is at 12 VDC. ...
I looked at the Moujen spec for the MS2 series switch (available here: http://www.moujenswitch.com/products/mj2/mj2_characteristics.htm) and decided it wasn't suitable for 10A operation at 12VDC. Under "Ratings":
If Bob or anyone has better data, I'd be glad to look at it.
But I don't think that substituting the switches for the relays would solve my
problem: I need an alternate electrical method of gear extension if something
in the circuit (but not the actuator) fails.
A separate switch wired to the battery in the correct polarity to only lower the
gear seems reasonable. But the motor is kept shorted by the relay contacts
in at least one failure mode of the circuit so the separate switch must interrupt
the wiring to the motor which adds a whole new failure mode.
If MIL-HKBK-217 has taught us anything, it is that adding components decreases
reliability :-)
--------
RV-8A
Independence, OR
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=487904#487904
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|