Lorn, et al

Rob is referring to the system downstream of the poppet valve.  It is true that the pump and the adjustable relief valve will not allow the system to actively pressurize beyond the the relief valve setting.  However once shut down, thermal heating can further raise the pressure level on the aircraft side.  There is a fixed thermal relief valve in the pump downstream of the poppet valve for just such a reason.  I do not know what its setting is.  It is definitely greater that 2,000 psi.  Given that the Oildyne pumps are rated to 3,000, I would not be surprised if the thermal relief valve rating is greater than 3,000 psi.

 

Chris Zavatson

N91CZ

360std

www.N91CZ.net

 

 

 

From: Lorn H Olsen <lorn@dynacomm.us>
To: lml@lancaironline.net
Sent: Monday, January 30, 2012 7:52 AM
Subject: [LML] Re: Hydraulic hoses

Rob,

If the hydraulic pump is working correctly, it has a 1,400 to 1,500 PSI override. The pressure in both the up and down side will never be greater than the override PSI.

Lorn

> From: "Stevens Family" <stevens5@swiftdsl.com.au>
> Date: January 29, 2012 5:16:11 PM EST
>
> A quick query from “Down Under”. I am up to building the hydraulic system for my Lancair 360, and need to purchase some hydraulic hose for the gear retract system. I understand the system theoretically operates at about 1500 PSI. However I have spoken to someone with experience on a similar aircraft, and he said that he has observed pressures over 2000 PSI, due to the heat soak phenomenon previously discussed on the LML.
>
> My question is, what pressure hose have others used in their aircraft? Do you have any suggestions or useful comments about building this system?
>
> Thanks in anticipation.
>
> Rob Stevens
> Perth, Western Australia.

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