X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 06 Apr 2013 09:47:58 -0400 Message-ID: X-Original-Return-Path: Received: from nm1-vm1.bullet.mail.ne1.yahoo.com ([98.138.91.36] verified) by logan.com (CommuniGate Pro SMTP 6.0.4) with ESMTPS id 6184193 for lml@lancaironline.net; Sat, 06 Apr 2013 09:34:43 -0400 Received-SPF: none receiver=logan.com; client-ip=98.138.91.36; envelope-from=chris_zavatson@yahoo.com Received: from [98.138.90.51] by nm1.bullet.mail.ne1.yahoo.com with NNFMP; 06 Apr 2013 13:34:10 -0000 Received: from [98.138.89.235] by tm4.bullet.mail.ne1.yahoo.com with NNFMP; 06 Apr 2013 13:34:10 -0000 Received: from [127.0.0.1] by smtp120-mob.biz.mail.ne1.yahoo.com with NNFMP; 06 Apr 2013 13:34:10 -0000 X-Yahoo-Newman-Id: 84405.26949.bm@smtp120-mob.biz.mail.ne1.yahoo.com X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: PJLmSsEVM1lINtHuyI8hQ3zmaKfc1Y4YmuvSeayEooAdYrT 5ChFF1ysHsRb7f5Au6Wr.IEih1SqIopFVQ4Yd9QQHuHw4XG236Pv0En99cQ5 XPV7G4L3.W_5drh7_Kpr2UMSfhQlHbxOlPo4tzQr1hSmbWRdAboulMDTbh92 bPJI3_2RObjGde9hVNxXIED89OX7ND4N_SIuCwqOQHw700c0Plk7V4FwaDh3 vn5bCaMiB0Xbcqgk_PqS3BSD6Q58tYZ6g6_cdQcb5sFbzuUauRDN7XwM8fS2 oKe4CX6HcWkpYZ52eUu_F21B5NeBZjrNk7dgq0X9B.BHGXBxxG0hHRWLBEwR xzPLemeso8uixYRmmD4lHwfDz92xC7NbRoztfkiMow96SHBCzF3_3l5Erclr ftX.9QSpy3JM.dbKSnWlLbK6Gq2FPx94Ah2sBNvWlQk7lfbWv3EKuD_suelq WOBBZkBBqPyzwpz2wREvOvhZO7zukr9sLNORlYg2tNVXZm7c.rfpqtenHlPH BTjgqnXUy5Y3MQLGnZZNLcH.77hdMIky6qLpebDuNjCltYhUnxNzZjGObGUi akFCSXFvGdg90.IGL1u4gyumBv7acqfuU X-Yahoo-SMTP: 076hgjCswBC.G6e0vm7vgvZ9JJ0zmeBo_Oyw X-Rocket-Received: from [192.168.1.78] (chris_zavatson@108.82.44.32 with xymcookie) by smtp120-mob.biz.mail.ne1.yahoo.com with SMTP; 06 Apr 2013 06:34:09 -0700 PDT References: In-Reply-To: Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=Apple-Mail-6618E542-07DC-4771-ADF8-E55E71BA3AE7 Received: from [108.82.44.32] by web121606.mail.ne1.yahoo.com via HTTP; Wed, 03 Apr 2013 07:13:32 PDT X-Original-Message-Id: <6E77398D-71D1-4C8A-91AA-A0C2297DE4C9@yahoo.com> Content-Transfer-Encoding: 7bit X-Mailer: iPhone Mail (9A405) From: Chris Zavatson Subject: Re: [LML] Re: LNC2 Old Pump Hydraulics Grief Content-Length: 14629 X-Original-Date: Sat, 6 Apr 2013 06:34:03 -0700 X-Original-To: Lancair Mailing List --Apple-Mail-6618E542-07DC-4771-ADF8-E55E71BA3AE7 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 Chris, You are on the right track. Lowering the low side PRV is worth giving a sho= t. Without looking more closely, I can't say if that would make your system= more prone to lock-up during the extension cycle. For the current pump des= ign I advocate raising the low side pressure. I am not sure how many of the= old style pumps are still in use today. Perhaps someone with one can chime= in regarding settings and any operational issues. The LB circuit was intro= duced specifically to eliminate what you running into. Chris Zavatson N91CZ 360std www.N91CZ.com From: Christopher Skelt To: lml@lancaironline.net=20 Sent: Tuesday, April 2, 2013 7:05 PM Subject: [LML] Re: LNC2 Old Pump Hydraulics Grief Chris, The pump is 108AA19-AL-3VT with a date stamp 10/89 and presumably predates t= he alphabet soup in your article. The spool is symmetrical. The dip stick t= hrough hole is also the filler for the metal cylindrical reservoir. Does th= e absence of a stand pipe mean the return is via the low side PRV during ret= ract? =20 I=E2=80=99ll screw up the shut-off on the high side. The low side pressure i= s building up over 1000 psi before the pump stops during retraction. Can I a= lso reduce the low side PRV operating pressure to limit the low side pressur= e buildup? I see no reason why it should be significantly more than the shu= toff pressure on the low side pressure switch. =20 Thank you for the reply=E2=80=94I wonder what folks did before the www. =20 Regards, Chris. =20 =20 From: Chris Zavatson Sent: Monday, April 01, 2013 10:21 AM To: lml@lancaironline.net Subject: Re: [LML] LNC2 Old Pump Hydraulics Grief =20 Chris, The behavior you describe indicates the lack of a functioning back pressure c= ircuit. Does your pump part number have an "LB" in the number? If instead i= t has an "LL", the pump pre-dates the LB back pressure circuit. If it is an= "LB" pump, your spool is in backwards and just needs to be flipped around. Unfortunately, the photo hints at an older pump. I see only one TRV and the= dip-stick through hole is drilled out. Also, there is no stand pipe for th= e return to reservoir. If it is indeed and older pump without a back pressure circuit (and they are= not retrofittable according to Parker), you'll need to raise the operating= pressure of the high side circuit to perhaps 1,500 psi. Right now your net= working pressure on the high side is reduced to: High side settings minus l= ow side PRV setting. -not enough to get the gear up cleanly. The ball a spring you removed are for the thermal relief. =20 Chris Zavatson N91CZ 360std http://www.n91cz.net/ =20 From: Christopher Skelt To: lml@lancaironline.net=20 Sent: Monday, April 1, 2013 4:08 AM Subject: [LML] LNC2 Old Pump Hydraulics Grief =20 This is for the aficionados of old hydraulic pumps. Mine is from 1989 and I= =E2=80=99m having trouble with the retract cycle. Since my post several mon= ths ago I have installed pressure gauges, rebuilt the nose leg actuator, seq= uence valve and gear door actuator, and serviced the pump with the kit from L= ancair. Same problems, but at least the pressure gauges help diagnose. =20 On the retract cycle pressure builds up on the low side as well as the high s= ide and the pump stops until the low side pressure drops, the pump restarts,= raises the gear a bit further, stops, and so on. Once the gear is up, the p= ressure on the low side drops off and high side pressure is maintained. The= se are symptoms of a reversed spool valve, but this pump=E2=80=99s is symmet= rical with a single o-ring. =20 Lowering is OK, and pressure is maintained in the down and locked position, s= o apparently no internal leaks.=20 =20 I guessed the return line was blocked, or the ball valve sticky. See the at= tached photos. The spring is very stiff and takes about 15 lb to close it a= bout 0.1 inches. With a port diameter of less than 1/10 inch, this translat= es into about 2000 psi to overcome that force. This doesn=E2=80=99t look li= ke it=E2=80=99s offering only 100 psi resistance and it seems beefier than t= he example on Chris Zavatson=E2=80=99s figure 14 on N91cz.com... Can anyone= confirm that the spring looks right or wrong=E2=80=94maybe Friday afternoon= at the factory? And where can I get a replacement return line spring and b= all?=20 =20 The photo of the pump shows the return valve location on the left.=20 =20 Thanks in advance. =20 Regards, Chris. =20 =20 =20 =20 =20 =20 =20 -- For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html =20 --Apple-Mail-6618E542-07DC-4771-ADF8-E55E71BA3AE7 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8
Chris,
You are on the right track.  Lo= wering the low side PRV is worth giving a shot.  Without looking more c= losely, I can't say if that would make your system more prone to lock-u= p during the extension cycle.  For the current pump design I advocate r= aising the low side pressure.  I am not sure how many of the old style p= umps are still in use today.  Perhaps someone with one can chime in reg= arding settings and any operational issues.  The LB circuit was introdu= ced specifically to eliminate what you running into.

Chris Zavatson
N91CZ
360std
www.N91CZ.com

From: Christopher Skelt <cskelt@= earthlink.net>
To: lml@lancaironline.net
<= b>Sent: Tuesday, April 2, 2013= 7:05 PM
Subject: [LML]= Re: LNC2 Old Pump Hydraulics Grief

Chris,
The pump is 108AA19-AL-3VT with a date stamp 10/89 and presumably preda= tes=20 the alphabet soup in your article.  The spool is symmetrical.  The= dip=20 stick through hole is also the filler for the metal cylindrical reservoir.&n= bsp;=20 Does the absence of a stand pipe mean the return is via the low side PRV dur= ing=20 retract?
 
I=E2=80=99ll screw up the shut-off on the high side.  The low side= pressure is=20 building up over 1000 psi before the pump stops during retraction.  Can= I=20 also reduce the low side PRV operating pressure to limit the low side pressu= re=20 buildup?  I see no reason why it should be significantly more than the=20= shutoff pressure on the low side pressure switch.
 
Thank you for the reply=E2=80=94I wonder what folks did before the www.=
 
Regards, Chris.
 
 
Sent: Monday, April 01, 2013 10:21 AM
Subject: Re: [LML] LNC2 Old Pump Hydraulics Grief
 
Chris,
The behavior you describe indicates the lack of a functioning bac= k=20 pressure circuit.  Does your pump part number have an "LB" in the=20 number?  If instead it has an "LL", the pump pre-dates the LB back pressure c= ircuit.  If it is an "LB"=20 pump, your spool is in backwards and just needs to be flipped=20 around.
Unfortunately, the photo hints at an older pump.  I see only= one=20 TRV an= d the dip-stick through hole is=20 drilled out.  Also, there is no stand pipe for the return to=20 reservoir.
If it is indeed and older pump without a back pressure circuit (a= nd=20 they are not = retrofittable according to=20 Parker),  you'll need to raise the operating pressure of the high side=20= circuit to perhaps 1,500 psi.  Right now your net working pressure on t= he=20 high side is reduced to: High side settings minus low side PRV setting.  = ; -not enough to get the gear up=20 cleanly.
The ball a spring you removed are for the thermal relief.=20
 
Chris Zavatson
N91CZ
360std
 
From: Christopher <= span class=3D"yiv548333812mark" id=3D"yiv548333812misspell-5">Skelt &= lt;cskelt@earthlink.net>
<= b>To: lml@lancaironline.net
Sent: Monday, April 1, 2013 4:08=20 AM
Subject: [LML] LNC2 Old Pump= Hydraulics Grief
 
This is for the aficionados of old hydraulic pumps.  Mine is from 1= 989=20 and I=E2=80=99m having trouble with the retract cycle.  Since my post s= everal=20 months ago I have installed pressure gauges, rebuilt the nose leg actuator, sequen= ce valve and gear=20 door actuator, and serviced the pump with the kit from Lancair.  Same=20= problems, but at least the pressure gauges help diagnose.
 
On the retract cycle pressure builds up on the low side as well as the h= igh=20 side and the pump stops until the low side pressure drops, the pump restarts= ,=20 raises the gear a bit further, stops, and so on.  Once the gear is up, t= he=20 pressure on the low side drops off and high side pressure is maintained.&nbs= p;=20 These are symptoms of a reversed spool valve, but this pump=E2=80=99s is sym= metrical=20 with a single o-ring.
 
Lowering is OK, and pressure is maintained in the down and locked posit= ion,=20 so apparently no internal leaks. 
 
I guessed the return line was blocked, or the ball valve sticky.  S= ee=20 the attached photos.  The spring is very stiff and takes about 15 lb to= =20 close it about 0.1 inches.  With a port diameter of less than 1/10 inch= ,=20 this translates into about 2000 psi to overcome that force.  This doesn=E2=80= =99t look like it=E2=80=99s offering only 100 psi=20 resistance and it seems  beefier than the example on Chris Zavatson=E2=80= =99s=20 figure 14 on N91cz.com...  Can=20 anyone confirm that the spring looks right or wrong=E2=80=94maybe Friday aft= ernoon at=20 the factory?  And where can I get a replacement return line spring and=20= ball? 
 
The photo of the pump shows the return valve location on the left. = ;=20
 
Thanks in advance.
 
Regards, Chris.
 
 
 
 
 
 
 

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