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down and locked gear failure

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Old 07-26-2012, 02:46 PM
  #1
gizmos
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Default down and locked gear failure

Has anyone else had gear failure with down and lock retract conversion? We have had 10 for 10 failure and I just read where two other guys with jets had the gear fail. Has anyone used the electric gear from dreamworks r/c? I would like to know what failed on your gear. This is the same gear that is sold by robart. Here is a picture of the gear that failed in a gear that weight is 3lbs each on a 80lb jet. I sent them back for repairs over 3 times each and still dont work. That little gear at the end of the number 11 blade is the gear that is pressed onto a little 50cent motor.Has anyone came up with a fix? Thanks for your help
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Old 07-27-2012, 12:40 AM
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Default RE: down and locked gear failure

If you've returned the gear three times for repair and they still don't work (providing they are being used correctly and within manufacturers specs), then the engineering is probably inadequate and not of merchantable quality for their intended purpose. In the UK, the supplier would have a case to answer with the likelyhood of a full refund of the purchace price.
Why should you be forced to look for a fix at your own expense on an item that I'm guessing is not cheap, and deserves to work correctly and reliably in the first place?

Good luck.

C8
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Old 07-27-2012, 11:27 AM
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Default RE: down and locked gear failure

Learn how to land. All retracts are delicate.
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Old 07-27-2012, 12:22 PM
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Default RE: down and locked gear failure


Quote:
ORIGINAL: Gohmer

Learn how to land. All retracts are delicate.
That's a little harsh, don't you think? There are 1 000 000 000 reasons a retract can fail and only one of them is a bad landing...
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Old 08-09-2012, 11:49 PM
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Default RE: down and locked gear failure

It looks like a manufacturing defect to me! We used to see a similar problem years ago with pressed on gears and slot car motors.

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Old 10-05-2012, 02:12 PM
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Default RE: down and locked gear failure

A few months ago I contacted Down and Locked regarding converting Robart 150HD9 retracts to electric. They said they would do it for $500 (incuding shipping)or I could wait for the DIY Robart conversion kits due out soon. I see Robart is now offering the conversion kits at $229.95 (plus shipping no doubt).
For these prices I would expect the products to be very high quality and to last forever (barring crashes), not having quality issues and failing as being reported. I thought the control system would shut off the drive if it overloaded, so the actuator would not destroy itself.

I now have doubts as whether or not to convert to electric, it did seem attractive for more scale retract speed, easy to wire in, Changing batteries rather than pumping up air cylinders and worying about leaks, and it should be reliable.
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Old 10-06-2012, 11:44 AM
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Default RE: down and locked gear failure

My opinion.

If the L G linkage is a TRUE over traveling locking link type. A severe nose down angle ...SHOULD..... break / crack the moving linkage parts.

If they are using a very high speed motor with a large amount of gearing..................The gears will break if the linkage DOES NOT mechanically get to the fully locked down position. PERIOD !!

How the lockdown position is made, determines geartrain breakage..PERIOD.

If you remove the motor & gear train............LOCK the gear down in fully down. Plain old Electricans tape wrapped around the down linkage is fine.
Land the plane several times. You would have your answer about the motor ...NOT>>>fully locking the gear COMPLETLY in the down position.

I designed many servos for industry. There is always a compromise between mechanical & electrical limits.

Poor design.

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Old 10-06-2012, 11:55 AM
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Default RE: down and locked gear failure

50 years ago I designed my own heavy duty large scale boat rudder servos with a simple motor, tube coupling, long 6-32 screw & a brass 6-32 nut. Then made brass connecting links to the rudder

Electric motors & high gear ratios can transmitt VERY high shock loads to the tiny gear tooth pressed onto the motor shaft.

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