Mailing List flyrotary@lancaironline.net Message #11876
From: Al Gietzen <ALVentures@cox.net>
Subject: RE: [FlyRotary] Re: oil injector pump
Date: Sat, 2 Oct 2004 08:29:35 -0700
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>

Subject: [FlyRotary] Re: oil injector pump

 

That is interesting.  Where exactly is the relief hole – near where the shaft comes through.  I don’t recall seeing anything when I had the pump off, although I couldn’t really get a close look because of things that are in the way.

 

I’m still wondering what happens with the blocked port; where does that oil go? Could that force leakage back along the shaft into the low-pressure side, maybe more than the relief port can handle.

 

Thanks for your help,

 

Al

 

Hi Al,

 

I just checked a disassembled pump. You are correct, it is a positive displacement system, however, the high pressure side has no connection to the pump mechanical drive. The drive section, including the drive shaft and the control shaft are in the oil intake area, and therefore low pressure.

The problem you see could be that the relieve hole on the drive shaft housing in the front cover is clogged, which would cause high pressure on the pump intake. The pump is designed for only a few inches of pressure on the intake.

Hope it helps.

 

Richard Sohn
N-2071U
unicorn@gdsys.net

 

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

From: Al Gietzen

Sent: Friday, October 01, 2004 12:13 PM

Subject: [FlyRotary] oil injector pump

 

My 20B came with a 4-port injector/metering pump from a 13B with three ports feeding the 3 rotors and one port blocked.  The pump began leaking (dripping out around the adjustment lever shaft) during the dyno runs; and then continuing to get worse as the pump finally stopped pumping after a total of maybe 4-5 hrs operation.  The replacement pump pumps very well, but immediately began showing some leakage.

 

I don’t know the outlet plumbing of the pump, but it is a positive displacement from the plunger, and as metering pump I’m thinking it may be setup for positive flow to each port; so blocking a port may be the cause of the leakage and failure.

 

Anyone have some input on this?

 

Thanks,

 

Al

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