REFLECTOR: HYDRAULIC PUMP

[gpoole]

Tom,

 

The hydraulic pump manufacturer is Parker Hannifin. If I remember correctly
the unit we use was originally designed for use in hydraulic actuated
hospital beds.

 

Greg in Sydney

 

http://www.parker.com/Products/  ..but don't ask me where to find it in
their catalogue.just spent 20 mins looking to no avail..

 

 

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Tom Martino
Sent: Monday, 17 July 2006 6:47 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: HYDRAULIC PUMP

 

Yes, as you will see in my original post, I do understand that "internal"
leaks can exist without external signs.  I have tested the entire system.
All that remains is the pump or the dump valve.  Do you know the pump
manufacturer?

 

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of dean fitzbag
Sent: Sunday, July 16, 2006 2:36 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: HYDRAULIC PUMP

 

Just because you don't see any leaks doesn't mean that there are none.  The
dump valve, the cylinders, and the sequence valve can leak internally.  This
sounds very hard to fix, but it isn't.  Buy some caps and double male
connectors.  Then start bypassing these components.  You may have more than
one leaking internally.  After each bypass bring the system up to pressure
with the gear up and see if the recycling goes away.  Of course neither or
either gear may not move depending on what has been bypassed.

----- Original Message ----- 

From: Tom Martino <mailto:tmartino at troubleshooter.com>  

To: reflector at tvbf.org 

Sent: Sunday, July 16, 2006 3:14 PM

Subject: REFLECTOR: HYDRAULIC PUMP

 

BACKGROUND:  This query comes as a result of my hydraulic pump turning on
and off quickly when gear was retracted.  A gear retraction test revealed
that the system is not holding pressure. 

QUESTION:  Can anyone tell me the actual Manufacturer, model and part number
for our Hydraulic Pumps? (I realize I can get them from Velocity, but I am
curious about some other things and would like to contact the manufacturer.)

Also . I am told there are "rebuild" kits for them.  I know the rebuild kit
includes "o" rings . but they are for keeping the fluid from leaking to the
outside world.  

My pump (and plumbing) had absolutely NO LEAKS - anywhere.

The only conclusion I could make is that the pressure was "bleeding off"
from the high side to the low side and the only parts in the pump that
maintain internal pressure are the "spring loaded metal-seated cone
check-valves" (one on each side).

Do the rebuild kits include new springs and cones?

Also . has anyone ever had the "dump valve" leak internally from high to low
side?  Without showing any wear or exterior leaking?  A local hydraulic shop
tells me they hardly ever see those simple quarter-turn vales go bad.

Any help on any of this would be great!

Tom

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