REFLECTOR: nose gear retract.

Bob Jackson (Jax Tech) bobj at JaxTechLLC.com
Fri Nov 22 22:41:00 CST 2013


John,

 

It is true that the standard nose gear cylinder has marginal travel -- often
not enough to both fully raise (and close the NG doors) as well as fully
lower (and overcenter lock) the nose gear leg.  

 

It would be easy to make a longer cylinder shaft -- and the Velocity factory
routinely has done that -- however, since to the best of my knowledge there
is no current manufacturer of new NG hydraulic cylinders, or at least one
willing to make a cylinder barrel that is an additional ~1/2" longer, which
would allow another 1/2" of travel (combined with a 1/2" longer shaft) and
solve the problem.  Maybe that situation has changed in the last year...

 

Meanwhile, I discovered one solution to increasing travel that's easy if you
don't mind disassembling the hydraulic cylinder.  When I took mine apart, I
noticed that there was insufficient space inside the end fitting of the
cylinder, and therefore the nut on the end of the shaft couldn't move aft
far enough to allow the internal plunger aft face to contact the forward
face of the aft fitting.

 

The plunger in the bottom of these first two pictures shows the shaft nut
being unable to retract all the way inside the aft fitting and the limited
resulting full aft travel of the shaft. 

 



 



 

After switching from the normal nylon lock nut to the lower profile
all-metal locknut, and after 'milling' out additional space in the 'pocket'
of the aft fitting so the nut can move all the way inside the fitting and
allow the plunger face to stop all the way against the forward face of the
aft fitting, I gained ~3/16 to 1/4" more overall cylinder travel -- enough
then to get both full up and full down nose gear travel.

 

Here's close up showing how I drilled out the cavity in the aft fitting to
create the additional ~1/4" of cylinder travel.

 



 

It's not hard to do with just a normal large drill bit, you don't need a
mill -- just be sure to clean away all the aluminum shavings before you put
it all back together!

 

Bob Jackson

Turbo-Cross Country Velocity XL/RG

850 hrs and loving every one!

N2XF

 

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of John Dibble
Sent: Friday, November 22, 2013 7:45 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: nose gear retract.

 

On 11/21/2013 7:04 PM, Jim & Sharon Beck wrote:

> Thanks Michael, Rene, John & Tom.  I went up  to the hangar to see 

> what I could find as a cause for the gear problem, Thought I found an 

> easy fix as the jam nut was loose and it appeared the piston rod 

> needed tightening.  gained about 1/4 inch shortening of the ram by 

> tightening.  Did a retract and that didn't seem to make any 

> appreciable difference.  all the other attach points did not seem to 

> have any play in them.  when I put the gear down it went over center 

> but did not contact the microswitch to give me a green front gear 

> light. I lengthened the rod about 1/8 inch and the lights went green 

> again.  it appears that when retracted, the wheel is about 1 inch 

> below where it needs to be for the doors to close completely.

 

If I understand correctly, there is not enough travel to have the gear 

fully retracted and fully extended.  Adjusting the piston rod won't help 

since more travel in one direction will take away from the other 

direction.  I had this problem when I replaced my gear leg.  The new one 

was somehow different.  I ended up adjusting to get my wheel all the way 

up and then adjusted the microswitch for the new gear up position.  

After thinking about it, I think that maximum gear travel is achieved by 

positioning the pivot location as high and as far forward as possible.  

Height being limited by the canard and forward limited by the bulkhead.

 

John

> when flying I think that vibration and air pressure  is causing the 

> wheel to raise another inch alowing the door to completely close but 

> the wheel is still resting on the door at that point.  at this point I 

> am wondering if the gear leg bent a bit when my old azuza nose wheel 

> disintegrated when the front tire blew last spring.  is stops rather 

> quickly when skidding on the front fork and would  have a lot of 

> pressure to bend in the direction that would give me that problem.  

> all the welds and attach points look solid and no real visible 

> wrinkles on the gear leg. Will call factory in the morning to see if I 

> can get the bend angles on the gear.  also to find if it is normal to 

> be able to easily raise gear 2 inches after retraction by reaching in 

> from the top.

> Thanks for all your ideas.  only thing I didn't check was the pressure 

> but the cylinder seems to pull in in as far before, only other change 

> I can see would be to shorten the stop spacer, but that makes me 

> wonder what else changed to cause the problem.

> Jim 173 RG

> 

> 

 

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