Cold weather, no gear!

[Guitarmaster]

I thought I had the problem solved, but no...  apparently.

The problem:  She refuses to put her wheels down when the temperature is cold.  I thought she just wanted to keep them tucked in because she doesn't like her feet to be cold, but I think it may be a deeper issue.
I have replaced both the up and down limit switches.  I know the squat switch can be an issue in cold weather with older biscuits, but why would the gear come up and not down?

One theory I have is, gravity pulling down on the gear depresses the switch upon retraction,  once in the wells, she takes her Prozac and becomes un-depressed.  Is that a word?    

This is without-a-doubt a temp related issue so that would point to a maladjusted squat switch and/or old biscuits.

The real question I have is:  Will the squat switch cause a failure to extend?  

[salty]

Land in the snow. 

 

Manic would be opposite of depressed. 

Edited December 22, 2016 by salty

[jlunseth]

It could be the switch but I would not necessarily assume that.  When it gets cold the friction increases in the system, grease thickens up, and if there was an impairment in the system that it could readily overcome in warm temps, it suddenly is unable to in cold.  Not uncommon in truly cold weather with all kinds of mechanical systems.  I have a garage door that works fine all summer long but gets cranky somewhere around 20 dF.  There is a bolt head that protrudes slightly into the track, a slide that moves through the track, and the slide will stop at that bolt head when the weather is cold enough, but not when it is warm.  Took me forever to find where the system was binding enough to stop in cold weather.   I think it would be good to put the plane up on stands, operate the gear, and observe the result.  If doing that in the cold does not tell the story, you might try it in the warm to see if there is a hitch of some kind at any point, that may be your culprit when the weather gets cold.

[Guitarmaster]

It could be the switch but I would not necessarily assume that.  When it gets cold the friction increases in the system, grease thickens up, and if there was an impairment in the system that it could readily overcome in warm temps, it suddenly is unable to in cold.  Not uncommon in truly cold weather with all kinds of mechanical systems.  I have a garage door that works fine all summer long but gets cranky somewhere around 20 dF.  There is a bolt head that protrudes slightly into the track, a slide that moves through the track, and the slide will stop at that bolt head when the weather is cold enough, but not when it is warm.  Took me forever to find where the system was binding enough to stop in cold weather.   I think it would be good to put the plane up on stands, operate the gear, and observe the result.  If doing that in the cold does not tell the story, you might try it in the warm to see if there is a hitch of some kind at any point, that may be your culprit when the weather gets cold.

I could agree, but there is no attempt to even try to extend. When cranking manually, it moves very easily and freely.

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[peevee]

maybe a bad electrical connection that gets worse in the cold?

[Andy95W]

Not sure what year F you have.

My thought is a limit switch or the down relay is old.  As the temperature drops, the switch or relay sticks and doesn't provide a current flow to the gear motor.  Based upon the schematic below, if your green down light goes out it is probably the down relay that is sticking.  Unfortunately, this will be hard to duplicate in a heated maintenance hangar.

[carusoam]

The following is for when the gear doesn't go up...

Often, the squat switch is the problem.  The old donuts have become older.  The cold weather exacerbates the problem...

I believe later Fs got the newly invented landing gear By-pass button to allow the gear to be retracted when the wrong status is read from the squat switch.

Expect to get new donuts to solve the primary problem, and consider getting a by-pass switch if you can.

PP thoughts only, not a mechanic.

Best regards,

-a-

[Andy95W]

I looked up your N#, it appears you have a 1975?

Attached is (I'm pretty sure) the schematic of your gear if it employs a squat switch.  It appears that the squat switch only interrupts power to the Up side of the circuit and has no bearing on the Down.

I am going to stick with my reasoning that either your down limit switch isn't allowing current to flow to your down relay or your down relay itself gets stuck and doesn't allow current to flow to the gear motor.

[N201MKTurbo]

Have you tried extending it just a bit and then trying the electric in both directions? Make sure to disengage the crank.

Just be aware this kind of experiment can lead to a gear up. 

Can you duplicate this on jacks?

 

[TTaylor]

When it does not lower the gear is the breaker popping?  Usually in gear driven systems the mechanical leverage is weakest at the end of the travel.  Have you removed the system, cleaned it throughly (washed all gears in a solvent bath) and lubed with fresh grease? The motors can also get weak areas in the brushes, extra load will cause them to not function.  The motor may need a rebuild.

Now is the time to replace the 20:1 gear with the 40:1 upgrade.   One gear up can ruin your day.   

[Yetti]

Please describe the symptom more:

No red light, Light stays green, No lights.

Neither one of those wiring diagrams may be the correct one.

Below is the relay that my 75' F connects to.   So That relay may be bad.   Those schematics don't match...  I have no clue how the motor reverses.  I would have done it like the schematic

[Guitarmaster]

1 hour ago, Yetti said:

Please describe the symptom more:

No red light, Light stays green, No lights.

Gear raises with no problem.  Normal sequence.  Handle up, green light out, red light on, all lights out.

Gear down:  Handle down, nothing.  Nada.  Lights stay off.  Gear doesn't move.  Start cranking: red light, crank some more, green light.

I wondered about that relay last year.  I called two MSC's and both said, "I have never seen that relay go bad."  However, they have had the down-limit switch go bad quite often; hence the switch replacement.

The problem is not duplicatable in the shop probably because once we get it up on jacks it warms up.  Of course, after that, it works fine.

All parts have been cleaned and re-greased. The hand crank operates smoothly all the way down.  Not much effort to get the gear down.  

No breaker tripping

I don't think it is a motor because it doesn't even try to move.  

[N201MKTurbo]

I've had the relay go bad. If you put it up on jacks and it fails to extend. carefully tap the relay and see if it goes down. Be vary careful when you tap the relay because big powerful things will start moving all around you.

http://www.skytecair.com/Solenoids.htm

 

 

Edited December 23, 2016 by N201MKTurbo

[Cyril Gibb]

2 hours ago, Guitarmaster said:

Gear down:  Handle down, nothing.  Nada.  Lights stay off.  Gear doesn't move.  Start cranking: red light, crank some more, green light

From what I understand, if you're cranking with the circuit breaker not pulled, you're playing with fire.  If whatever electrical that wasn't working starts working, that crank will whip around at a rate that will really surprise you, and potentially cause injury in addition to perhaps jamming or breaking the actuator.  At that point, your day will become much worse.

[N201MKTurbo]

3 minutes ago, Cyril Gibb said:

From what I understand, if you're cranking with the circuit breaker not pulled, you're playing with fire.  If whatever electrical that wasn't working starts working, that crank will whip around at a rate that will really surprise you, and potentially cause injury in addition to perhaps jamming or breaking the actuator.  At that point, your day will become much worse.

You are not playing with fire, you are playing with money! 

You better hope the handle keeps spinning because if it stops, you are looking at big bucks to fix it. At least now you can get a replacement coupler. For a while you had to get one out of a scraped plane. $500 used...

[Guitarmaster]

From what I understand, if you're cranking with the circuit breaker not pulled, you're playing with fire.  If whatever electrical that wasn't working starts working, that crank will whip around at a rate that will really surprise you, and potentially cause injury in addition to perhaps jamming or breaking the actuator.  At that point, your day will become much worse.

No. The breaker is pulled.

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[Guitarmaster]

3 hours ago, N201MKTurbo said:

I've had the relay go bad. If you put it up on jacks and it fails to extend. carefully tap the relay and see if it goes down. Be vary careful when you tap the relay because big powerful things will start moving all around you.

http://www.skytecair.com/Solenoids.htm

 

 

Thanks for the link!  Maybe ill try putting the gear up while on jacks and freeze the relay.  Maybe the problem will rear it's ugly head that way.

[Piloto]

Have the plane on jacks with gear retracted. With a Cold Spray can spray on the relays and switches to spot the faulty component.

 https://www.bing.com/images/search?q=cold+spray+can&qpvt=cold+spray+can&qpvt=cold+spray+can&qpvt=cold+spray+can&FORM=IGRE

José

[Marauder]

Matt -- if you are not popping the breaker, it is either the relay or the down switch. Also, check your gear switch to make sure everything is snug.


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[Yetti]

So we have it down to...

The down circuit.

Half leg of motor has gone out

Down Wiring

Down switchs

Solinoid

 

[N201MKTurbo]

If you are flying and it does it, stomp your feet on the floor kind of hard and see if it gets it going.

[bonal]

Hope you find the culprit, Johnson bars rule. 

[Guitarmaster]

If you are flying and it does it, stomp your feet on the floor kind of hard and see if it gets it going.

Never thought about that. Good idea! I'll try it!

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[Yetti]

OK after checking some tractor forums.... no really.   This is what the three wires are for coming off the solenoid. from the picture above.   Orange is battery.  Green is the brake in the motor.   The 4th  terminal in the solenoid provides 12V to the brake in the motor when energized.   The brake in the motor holds the armature so the gear does not vibrate down.

The brake in the motor is what my actuator is out getting IRANed.

Merry Christmas

[Guitarmaster]

On 12/25/2016 at 7:13 AM, Yetti said:

OK after checking some tractor forums.... no really.   This is what the three wires are for coming off the solenoid. from the picture above.   Orange is battery.  Green is the brake in the motor.   The 4th  terminal in the solenoid provides 12V to the brake in the motor when energized.   The brake in the motor holds the armature so the gear does not vibrate down.

The brake in the motor is what my actuator is out getting IRANed.

Merry Christmas

Tractor forums...  Bahahaha!!  That's almost as good as the Ford alternator and voltage regulator!