piper arrow gear over center locks
08-28-2009, 09:18 PM
#1
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Joined APC: Jan 2008
Position: CRJ
Posts: 59
piper arrow gear over center locks
On the landing gear system in the Piper arrow, when the gear comes down the over center lock hooks engage locking it in the down position, BUT my question is when u bring the gear back up how are those disengaged to allow it to come back up? I couldn't find it in the POH.
08-28-2009, 09:57 PM
#2
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Joined APC: Dec 2007
Posts: 216
I tried looking it up also...and couldn't come up with anything. I'm guessing, but maybe when you retract, it pushes the gear farther, or hyperextends it so that the downlock hooks disengage. Just an idea though. Maybe one of the A and P's on here can give some insight.
09-05-2009, 06:13 AM
#5
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I'm not sure where you train, but if you ever see an Arrow or Seminole up on jacks in maintenance, check to see if the mx personnel will allow you to operate the gear while you're under it. Watching the series of events happen will clear up many of your future questions.
09-05-2009, 06:46 AM
#6
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Posts: 73
As I have said in other post it has been a while since I have taught and my spelling could use some help but here goes...
Most over center linkages are used so that when a heavy force is applied, ie a hard landing, the gear does not fold up the way it came down. Engineers designer gear to swing freely to make the normal and emergency gear extension systems that have more than enough power to get the gear down.
As for the over center here is an analogy, notice I said analogy not good analogy...
Imagine your leg being the linkage in the gear. When your leg is bent that would be like the gear being retracted and when your leg is straight it is like being extended. Your knee would be like the over center, when your knee is "locked" that is like being over centered. No how would be gear retract from the over center? Well now imagine that we pull via hydraulic actuator or jackscrew from just above the knee say a couple inches not straight up because your knee is locked and it wont do any good. But if you pull on a 45 degree angle your knee will extend a bit and then move freely towards a bent or retracted position.
Not the best but hope it gets the job done for you, some days I wish I was back in front of the white board...
Most over center linkages are used so that when a heavy force is applied, ie a hard landing, the gear does not fold up the way it came down. Engineers designer gear to swing freely to make the normal and emergency gear extension systems that have more than enough power to get the gear down.
As for the over center here is an analogy, notice I said analogy not good analogy...
Imagine your leg being the linkage in the gear. When your leg is bent that would be like the gear being retracted and when your leg is straight it is like being extended. Your knee would be like the over center, when your knee is "locked" that is like being over centered. No how would be gear retract from the over center? Well now imagine that we pull via hydraulic actuator or jackscrew from just above the knee say a couple inches not straight up because your knee is locked and it wont do any good. But if you pull on a 45 degree angle your knee will extend a bit and then move freely towards a bent or retracted position.
Not the best but hope it gets the job done for you, some days I wish I was back in front of the white board...
11-09-2009, 08:41 PM
#7
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Joined APC: Mar 2007
Position: ERJ Right
Posts: 541
Take a look at the gear on the arrow and you will see the pin being held in place by the spring loaded over center lock. When this lock is perfectly in place it closes the micro-switch completing the circuit. Now take a look at that same metal lock with the spring attached, notice where the hydraulic arm connects to the gear???
Right on that same piece of metal known as the over center lock. Now imagine as the gear is retracted pressure builds in the hydraulic arm which then initially pulls up that metal lock, the lock is bolted to the half of the gear linkage and eventually the entire gear linkage is pulled up.
Hope that helps.
Right on that same piece of metal known as the over center lock. Now imagine as the gear is retracted pressure builds in the hydraulic arm which then initially pulls up that metal lock, the lock is bolted to the half of the gear linkage and eventually the entire gear linkage is pulled up.
Hope that helps.
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