Hydraulic Cylinder Rigging

Submitted by Anonymous on

Forums: 

From: John Cooper <snopercod [at] comporium.net>
Sender: <marv [at] lancaironline.net>
Subject: [LML] Hydraulic Cylinder Rigging
Date: Wed, 28 May 2014 07:37:01 -0400
To: <lml [at] lancaironline.net>

Scott--



The portion of your recent post  on the pressure spike topic (which
I have highlighted in red, below) has my head spinning. The reason
is that I have spent the last two weeks re-rigging my hydraulic
cylinders because I did it wrong the first time around. I had
previously rigged the cylinders to keep pressure on the system when
the gear was retracted, and had the cylinders bottom out
just after the gear was down as you implied they should.  According
to Pg. 292 of the plans, the way I did it was exactly backwards, and
that scheme seems to have actually bent one my cylinder attach
bolts. If you go to Pg. 292 of the Builder's
Manual Ch. 11 , it emphasizes that the cylinders must bottom
out internally (or against the supplied aluminum spools) when the
gear is retracted. But paragraph 6 goes on to state: "The
gear down side, due to reduced geometry, does not require that the
system be bottomed out." That's why I posed my original question
about going to 800 PSI rather than 500 PSI.



So I've rigged my cylinders per the instructions on Pg. 292:
Cylinders bottomed out against the spool pieces when the gear is
retracted, but NOT bottomed out when the shaft is extended
and the gear is down. Therefore I have low-side pressure pushing on
the over-center link when the gear is down. Is this wrong? Would it
even be possible to rig the cylinders so they are bottomed out both
with the gear up and the gear down?



I note that the plans describe the original placement of the main
gear cylinders back on Pg. 168 in Chapter 5, but the details of
their action and adjustment comes 124 pages later in Chapter 11.
It's almost like Lance added a page due to some confusion on this
issue.  (I know I'm confused.)



Help!



  --John


At least for LNC2's the down actuators are to assist
gravity and the nose gear gas spring in order to extend the
gear.  The infamous rat-trap springs on the main gear are to
merely lock the over center.  Thus, not much hydro pressure is
needed to extend the mains and nose even at 122 Kts (max
extension speed).
 
When the gear is extended the actuators under pressure are
merely used to keep the over center links locked (kinda like a
backup system).  The actuator down stops must be set to keep
hydro pressure off of the links.  "Why?" You might ask.  Well,
examine the geometry - the force triangle is from the pivot to
the link to the link-spar attach point and back to the pivot
along the spar.  If enough hydro force is applied to the
actuator, the rod may become bent or the now excessive force
present at the link-spar connection can delaminate it from the
spar.  Hard landings with some side loads have caused failure
there and that is why a service bulletin recommends putting a
reinforcing plate between the link-spar attach point and the
upper spar.
 
Yes, excessive
pressure without proper down stop rigging can cause
problems.
 
Scott Krueger

Hydraulic Cylinder Rigging

Submitted by Anonymous on

From: <Sky2high [at] aol.com>
Subject: Re: [LML] Hydraulic Cylinder Rigging
Date: Wed, 28 May 2014 08:18:48 -0400 (EDT)
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message

John,
 
I think you pointed to the wrong section.  Also, I think that manual
is either for a 235 or is just ancient.  To avoid confusion,  read the
2 pages attached for a discussion of up-stops.  The modern manual is
available either at the LML site or someone will indicate how to get it.
 
The essential down stop is the full mechanical extension of the hydro
cylinders where the piston stops against the fwd end of the actuator for the
reasons I mentioned.
 
Yes, both stops can be achieved.  Set the down stop first and then
adjust the up-stop via any method that works - added washers, cutting
the stop, etc.
 
Scott
In a message dated 5/28/2014 6:37:11 A.M. Central Daylight Time,
snopercod [at] comporium.net writes:

Scott--

The portion of your recent post  on the
pressure spike topic (which I have highlighted in red, below) has my head
spinning. The reason is that I have spent the last two weeks re-rigging my
hydraulic cylinders because I did it wrong the first time around. I had
previously rigged the cylinders to keep pressure on the system when the gear
was retracted, and had the cylinders bottom out just after the gear was
down as you implied they should.  According to Pg. 292 of the plans, the
way I did it was exactly backwards, and that scheme seems to have actually
bent one my cylinder attach bolts. If you go to Pg. 292 of the Builder's
Manual Ch. 11 , it emphasizes that the cylinders must bottom out
internally (or against the supplied aluminum spools) when the gear is
retracted. But paragraph 6 goes on to state: "The gear down side, due
to reduced geometry, does not require that the system be bottomed out." That's
why I posed my original question about going to 800 PSI rather than 500
PSI.

So I've rigged my cylinders per the instructions on Pg. 292:
Cylinders bottomed out against the spool pieces when the gear is retracted,
but NOT bottomed out when the shaft is extended and the gear is down.
Therefore I have low-side pressure pushing on the over-center link when the
gear is down. Is this wrong? Would it even be possible to rig the cylinders so
they are bottomed out both with the gear up and the gear down?

I note
that the plans describe the original placement of the main gear cylinders back
on Pg. 168 in Chapter 5, but the details of their action and adjustment comes
124 pages later in Chapter 11. It's almost like Lance added a page due to some
confusion on this issue.  (I know I'm
confused.)

Help!

  --John

At least for LNC2's the down actuators are to assist gravity and the
nose gear gas spring in order to extend the gear.  The infamous
rat-trap springs on the main gear are to merely lock the over center. 
Thus, not much hydro pressure is needed to extend the mains and nose
even at 122 Kts (max extension speed).
 
When the gear is extended the actuators under pressure are
merely used to keep the over center links locked (kinda like a backup
system).  The actuator down stops must be set to keep hydro
pressure off of the links.  "Why?" You might ask.  Well,
examine the geometry - the force triangle is from the pivot to the link to
the link-spar attach point and back to the pivot along the spar.  If
enough hydro force is applied to the actuator, the rod may become bent
or the now excessive force present at the link-spar connection can
delaminate it from the spar.  Hard landings with some side loads have
caused failure there and that is why a service bulletin recommends putting a
reinforcing plate between the link-spar attach point and the upper
spar.
 
Yes, excessive pressure without
proper down stop rigging can cause problems.
 
Scott
Krueger

Hydraulic Cylinder Rigging

Submitted by Anonymous on

From: Chris Zavatson <chris_zavatson [at] yahoo.com>
Sender: <marv [at] lancaironline.net>
Subject: Re: [LML] Hydraulic Cylinder Rigging
Date: Wed, 28 May 2014 14:14:50 -0400
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message
John,
By the time I picked up my kit in '95, the approach to adjusting hydraulic stops had evolved - although I have not seen a revision in the manual.  The rod-end bearing is used to adjust the extended length and the spacer adjusts the retracted length.
Note also that the system pressure will far exceed the set point of the switches. Attached is a pic taken after lunch in Spokane - prior leg was at 16.5k.  Low side pressure has risen
to 1,200 psi while warming on the ramp.  The system needs to absorb a broad range of pressures without damage.
Chris Zavatson
N91CZ
360std
 


On Wednesday, May 28, 2014 7:10 AM, Chris Zavatson <chris_zavatson [at] yahoo.com> wrote:



John,
By the time I picked up my kit in '95, the approach to adjusting hydraulic stops had evolved - although
I have not seen a revision in the manual.  The rod-end bearing is used to adjust the extended length and the spacer adjusts the retracted length.
Note also that the system pressure will far exceed the set point of the switches. Attached is a pic taken after lunch in Spokane - prior leg was at 16.5k.  Low side pressure has risen to 1,200
psi while warming on the ramp.  The system needs to absorb a broad range of pressures without damage.
Chris Zavatson
N91CZ
360std


On Wednesday, May 28, 2014 4:37 AM, John Cooper <snopercod [at] comporium.net> wrote:



Scott--



The portion of your recent post  on the pressure spike topic (which
I have highlighted in red, below) has my head spinning. The reason
is that I have spent the last two weeks re-rigging my hydraulic
cylinders because I did it wrong the first time around. I had
previously rigged the cylinders to keep pressure on the system when
the gear was retracted, and had the cylinders bottom out
just after the gear was down as you implied they should.  According
to Pg. 292 of the plans, the way I did it was exactly backwards, and
that scheme seems to have actually bent one my cylinder attach
bolts. If you go to Pg. 292 of the Builder's
Manual Ch. 11 , it emphasizes that the cylinders must bottom
out internally (or against the supplied aluminum spools) when the
gear is retracted. But paragraph 6 goes on to state: "The
gear down side, due to reduced geometry, does not require that the
system be bottomed out." That's why I posed my original question
about going to 800 PSI rather than 500 PSI.



So I've rigged my cylinders per the instructions on Pg. 292:
Cylinders bottomed out against the spool pieces when the gear is
retracted, but NOT bottomed out when the shaft is extended
and the gear is down. Therefore I have low-side pressure pushing on
the over-center link when the gear is down. Is this wrong? Would it
even be possible to rig the cylinders so they are bottomed out both
with the gear up and the gear down?



I note that the plans describe the original placement of the main
gear cylinders back on Pg. 168 in Chapter 5, but the details of
their action and adjustment comes 124 pages later in Chapter 11.
It's almost like Lance added a page due to some confusion on this
issue.  (I know I'm confused.)



Help!



  --John

At least for LNC2's the down actuators are to assist
gravity and the nose gear gas spring in order to extend the
gear.  The infamous rat-trap springs on the main gear are to
merely lock the over center.  Thus, not much hydro pressure is
needed to extend the mains and nose even at 122 Kts (max
extension speed).
 
When the gear is extended the actuators under pressure are
merely used to keep the over center links locked (kinda like a
backup system).  The actuator down stops must be set to keep
hydro pressure off of the links.  "Why?" You might ask.  Well,
examine the geometry - the force triangle is from the pivot to
the link to the link-spar attach point and back to the pivot
along the spar.  If enough hydro force is applied to the
actuator, the rod may become bent or the now excessive force
present at the link-spar connection can delaminate it from the
spar.  Hard landings with some side loads have caused failure
there and that is why a service bulletin recommends putting a
reinforcing plate between the link-spar attach point and the
upper spar.
 
Yes, excessive
pressure without proper down stop rigging can cause
problems.
 
Scott Krueger

Hydraulic Cylinder Rigging

Submitted by Anonymous on

From: John Cooper <snopercod [at] comporium.net>
Sender: <marv [at] lancaironline.net>
Subject: Re: [LML] Hydraulic Cylinder Rigging
Date: Wed, 28 May 2014 14:16:14 -0400
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message

Scott--



Yes, the information I provided was both ancient and from the
235 manual (grin). Thanks
for providing better information from the 320 manual; Lance
did a much nicer job of explaining things in that manual than
in the ancient one. I read your attachment twice, though, and
didn't find anything about "down stops" or adjusting the rod
end with the gear down first. Maybe I'm just getting senile?
The pages you sent do indicate, though, that the up stop can
be adjusted with the rod end (true), but that would mess up
the down stop that you just adjusted, wouldn't it?



As I'm sure you know, adjusting the rod end bearing effects both
the up and down stops, while the aluminum "spool piece"
effects only the up stop. So you're suggesting that I first
adjust the down stop with the rod-end, and then fiddle with
the length of the spool piece and/or washers to adjust the up
stop? That sounds pretty tricky but I'll try it. Frankly, I
don't think I can screw the rod ends in far enough to achieve
a proper down stop as you are describing.



Thanks--



  --John



I think you pointed to the wrong section. 
Also, I think that manual is either for a 235 or is
just ancient.  To avoid confusion,  read the 2 pages
attached for a discussion of up-stops.  The
modern manual is available either at the LML site or
someone will indicate how to get it.


 


The essential down stop is the full
mechanical extension of the hydro cylinders where the
piston stops against the fwd end of the actuator for
the reasons I mentioned.


 


Yes, both stops can be achieved.  Set the
down stop first and then adjust the up-stop via any
method that works - added washers, cutting the stop,
etc.


 


Scott

Hydraulic Cylinder Rigging

Submitted by Anonymous on

From: <Sky2high [at] aol.com>
Subject: Re: [LML] Re: Hydraulic Cylinder Rigging
Date: Wed, 28 May 2014 14:53:17 -0400 (EDT)
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message

John,
 
If the actuator is too long fro the down stop either relocate the aft end
mounting or cut off some of the threaded end (within reason).  The uo stop
can be positioned with some more nuts on the shaft or cut it down a bit if too
long.
 
Again, if 500 to 800 psi is pressure applied to the over center link
(main gear), that pressure is translated as a pre-load to the point where the
link is mounted on the spar.  Additional load from a bad landing can cause
delamination of that mounting block (especially true if you are using the hard
donuts for suspension, high tire pressure, etc.).
 
Good luck.
 
Scott
 
PS There is a service bulletin that describes a reinforcement phenolic
plate added between the top of the mounting block and the upper spar cap. 
See if you can get it from Lancair.
 
 
In a message dated 5/28/2014 1:25:28 P.M. Central Daylight Time,
snopercod [at] comporium.net writes:

Scott--

Yes, the information I provided was
both ancient and from the 235 manual
(grin). Thanks for providing better
information from the 320 manual; Lance
did a much nicer job of explaining things in that manual than in the ancient
one. I read your attachment twice, though, and didn't find anything about
"down stops" or adjusting the rod end with the gear down first. Maybe I'm just
getting senile? The pages you sent do indicate, though, that the up stop can
be adjusted with the rod end (true), but that would mess up the down stop that
you just adjusted, wouldn't it?

As I'm sure you know, adjusting the rod
end bearing effects both the up and down stops, while the aluminum
"spool piece" effects only the up stop. So you're suggesting that I first
adjust the down stop with the rod-end, and then fiddle with the length of the
spool piece and/or washers to adjust the up stop? That sounds pretty tricky
but I'll try it. Frankly, I don't think I can screw the rod ends in far enough
to achieve a proper down stop as you are
describing.

Thanks--

  --John

I think you pointed to the wrong section.  Also, I think
that manual is either for a 235 or is just ancient.  To avoid
confusion,  read the 2 pages attached for a discussion of
up-stops.  The modern manual is available either at the LML site
or someone will indicate how to get
it.

 

The essential down stop is the full mechanical extension of
the hydro cylinders where the piston stops against the fwd end of the
actuator for the reasons I
mentioned.

 

Yes, both stops can be achieved.  Set the down stop
first and then adjust the up-stop via any method that works - added washers,
cutting the stop, etc.

 

Scott

Hydraulic Cylinder Rigging

Submitted by Anonymous on

From: Ames Angier M. <n4zq [at] verizon.net>
Subject: Hydraulic Cylinder Rigging
Date: Wed, 28 May 2014 22:40:32 -0400
To: John Cooper <snopercod [at] comporium.net>
Cc: List Lancair Mailing <lml [at] lancaironline.net>
Message Header


Undecoded Message

John,


You must achieve a positive STOP at both the fully retracted and fully extended positions in order to remove stress at the cylinder attach points.
Do whatever is necessary to obtain this result.
In the retracted position, a spacer or washers on the shaft will work but a single spacer of the correct length is best. If a shaft turns out to be too
long in the extended position, you can shorten the throw by adding a spacer on the shaft INTERNALLY.

In this pic you can see the internal spacer I used to shorten the throw of my nose gear cylinder.

Hope this helps.

Angier Ames
N4ZQ

Hydraulic Cylinder Rigging

Submitted by Anonymous on

From: Greenbacks, UnLtd. <n4zq [at] verizon.net>
Subject: Re: Hydraulic Cylinder Rigging
Date: Thu, 29 May 2014 08:38:37 -0400
To: John Cooper <snopercod [at] comporium.net>
Cc: List Lancair Mailing <lml [at] lancaironline.net>
Message Header


Undecoded Message

If you have rigged correctly, two conditions exist:

In the down position and with the cylinder fully extended, there will be little to no force imparted to the mounting points…just enough shaft movement to have the gear links

go over center and lock.

In the up position, the only force on the mounting points will be the actual weight of the gear.

This is what you want to achieve. Otherwise, 12-1500psi applied to the attach points could cause delimitation/failure over time.

It’s no big deal to get it just right.



:-)





On May 29, 2014, at 6:44 AM, John Cooper <snopercod [at] comporium.net> wrote:



> Angier--

>

> Nice work on the internal stop. My problem is that both you and Chris Z. tell me I "must" provide a down stop, but that's in direct contradiction to the instructions in the manual. If it's mandatory, then why no Service Bulletin? I understand that there were a lot of mistakes and omissions in the manual, but I'm wondering if there have been any instances of over-center links failing due to having down side pressure on them? Have there been any other actual problems, or is this just a theoretical "nice thing to do"?

>

> Best--

>

>  --John

>



Hydraulic Cylinder Rigging

Submitted by Anonymous on

From: Bill Harrelson <n5zq [at] verizon.net>
Sender: <marv [at] lancaironline.net>
Subject: Re: [LML] Re: Hydraulic Cylinder Rigging
Date: Thu, 29 May 2014 13:12:34 -0400
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message
John wrote:
 
“
Frankly, I don't think I can screw the rod ends in far enough to achieve a
proper down stop as you are describing.”
 
 
 
 
 
John,
 
If I remember correctly, a highly
speculative concept considering it’s been a couple of decades, I cut a little
bit of thread off of my rods to be able to adjust the rod end for the down stop
as Scott described. Then, as you deduced, play with the spools and washers to
adjust the up stop.
 
Bill Harrelson
formerly N5ZQ 320 2,250
hrs
now        N6ZQ  IV 550
hrs
 

Hydraulic Cylinder Rigging

Submitted by Anonymous on

From: John Cooper <snopercod [at] comporium.net>
Sender: <marv [at] lancaironline.net>
Subject: [LML] Re: Hydraulic Cylinder Rigging
Date: Thu, 29 May 2014 13:13:09 -0400
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message

Scott--



I can tell you right now that there's no way in hell that I'm going
to relocate the mounting block for the aft end of the MLG
cylinders.  I've already incorporated the SB on beefing up the OC
link attach point so I'm just going to take my chances with a little
pressure on the OC link since the factory says that's OK (I posed
the manual section earlier). I agree with you that it would be
"better" to have a down stop, but the 235 manual says "not
required".  If you have a 320 manual section or a SB that
contradicts that, I'd sure like to see it. I've read both manuals
and couldn't find any words requiring a down stop. So if I can't get
a down stop adjusted, I'm just not going to worry about it.



I've got the Ong's Debongers, not the donuts. Also, I've already cut
off ~1/4" of the threaded end of the cylinders because I couldn't
get them short enough - the rod end was bottoming out internally.



Best--



  --John


John,


 


If the actuator is too long fro the down stop either
relocate the aft end mounting or cut off some of the
threaded end (within reason).  The uo stop can be
positioned with some more nuts on the shaft or cut it down
a bit if too long.


 


Again, if 500 to 800 psi is pressure applied to the
over center link (main gear), that pressure is translated
as a pre-load to the point where the link is mounted on
the spar.  Additional load from a bad landing can cause
delamination of that mounting block (especially true if
you are using the hard donuts for suspension, high tire
pressure, etc.).


 


Good luck.


 


Scott


 


PS There is a service bulletin that describes a
reinforcement phenolic plate added between the top of the
mounting block and the upper spar cap.  See if you can get
it from Lancair.

Hydraulic Cylinder Rigging

Submitted by Anonymous on

From: <Sky2high [at] aol.com>
Subject: Re: [LML] Re: Hydraulic Cylinder Rigging
Date: Thu, 29 May 2014 13:18:01 -0400 (EDT)
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message

John,
 
Whatever.  It's experimental anyway.
 
Scott
 
In a message dated 5/29/2014 12:13:14 P.M. Central Daylight Time,
snopercod [at] comporium.net writes:

Scott--

I can tell you right now that there's no way in hell
that I'm going to relocate the mounting block for the aft end of the MLG
cylinders.  I've already incorporated the SB on beefing up the OC link
attach point so I'm just going to take my chances with a little pressure on
the OC link since the factory says that's OK (I posed the manual section
earlier). I agree with you that it would be "better" to have a down stop, but
the 235 manual says "not required".  If you have a 320 manual section or
a SB that contradicts that, I'd sure like to see it. I've read both manuals
and couldn't find any words requiring a down stop. So if I can't get a down
stop adjusted, I'm just not going to worry about it.

I've got the Ong's
Debongers, not the donuts. Also, I've already cut off ~1/4" of the threaded
end of the cylinders because I couldn't get them short enough - the rod end
was bottoming out internally.

Best--

  --John

John,

 

If the actuator is too long fro the down stop either relocate the
aft end mounting or cut off some of the threaded end (within reason). 
The uo stop can be positioned with some more nuts on the shaft or cut it
down a bit if too long.

 

Again, if 500 to 800 psi is pressure applied to the over
center link (main gear), that pressure is translated as a pre-load to the
point where the link is mounted on the spar.  Additional load from a
bad landing can cause delamination of that mounting block (especially true
if you are using the hard donuts for suspension, high tire pressure,
etc.).

 

Good luck.

 

Scott

 

PS There is a service bulletin that describes a reinforcement
phenolic plate added between the top of the mounting block and the upper
spar cap.  See if you can get it from
Lancair.

Hydraulic Cylinder Rigging

Submitted by Anonymous on

From: Greenbacks, UnLtd. <n4zq [at] verizon.net>
Subject: Hydraulic Cylinder Rigging
Date: Thu, 29 May 2014 22:53:16 -0400
To: John Cooper <snopercod [at] comporium.net>
Cc: List Lancair Mailing <lml [at] lancaironline.net>
Message Header


Undecoded Message

John,



Take the time to get it right…

Disconnect all three cylinders from their respective gear and select gear down. If you thread the rod ends all the way in and the shaft is still too long, you need to fabricate an internal stop.

Once you nail the down stop, you can set the up stop using the kit supplied spacer and if need be, adding additional washers.



Angier Ames

N4ZQ

Hydraulic Cylinder Rigging

Submitted by Anonymous on

From: John Cooper <snopercod [at] comporium.net>
Sender: <marv [at] lancaironline.net>
Subject: [LML] Re: Hydraulic Cylinder Rigging
Date: Fri, 30 May 2014 08:02:09 -0400
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message

Bill, Angier, Chris, and all--



While installing my new Matco brake assembly on the left wheel
today, I fiddled with the hydraulic cylinder rigging. I cut about
1/4" off the threaded shaft, and was barely able to screw
the rod end in far enough to obtain the "down stop" that you guys
recommend. Unfortunately, the aluminum spool piece which I had
previously shortened, no longer provides an "up stop". I immediately
called Michelle at Lancair and thankfully she still has them in
stock (either .93 long or 1.25 long). So it appears that I will
be able to achieve hard stops both retracted and extended - on
the left gear anyway...



Thanks for all the helpful advice on this. I feel so foolish for not
knowing this needed to be done --John


John,
 
If I remember
correctly, a highly speculative concept considering it’s
been a couple of decades, I cut a little bit of thread off
of my rods to be able to adjust the rod end for the down
stop as Scott described. Then, as you deduced, play with the
spools and washers to adjust the up stop.
 
Bill Harrelson

Hydraulic Cylinder Rigging

Submitted by Anonymous on

From: Greenbacks, UnLtd. <n4zq [at] verizon.net>
Subject: Hydraulic Cylinder Rigging
Date: Fri, 30 May 2014 08:40:46 -0400
To: List Lancair Mailing <lml [at] lancaironline.net>
Message Header


Undecoded Message

"If you thread the rod ends all the way in and the shaft is still too long, you need to fabricate an internal stop.”



I should have said to try to shorten the rods by cutting off threads first but of course you need to leave enough threads

to run in past the inspection hole. If the rod is still too long, proceed to plan b….



Angier Ames

N4ZQ