REFLECTOR: engine driven fuel pump (history lesson)

[Brian Michalk]

Might I also add that there is no return feed.  The plunger extension 
causes the diaphragm to draw in fuel, and then expel using spring force.

If the outlet is blocked, the plunger does not extend the diaphragm any 
farther, it is extended and held there by fuel pressure.  No relief 
valve needed.  Nice thing when you are trying to not heat up the fuel.

Laurence Coen wrote:
> I'm sure that you've all heard of Glen Curtis and the Curtis Aircraft 
> Co. Glen started out making bicycles and advanced to motorcycles which 
> used Schebler carburetors. Curtis Motorcycle bought Schebler and made it 
> a division.  When Glen got into the airplane business he sold the 
> motorcycle business and it was renamed Marvel Motorcycle Co.  The Marvel 
> Schebler carb was jointly developed by Curtis Aircraft and the Marvel 
> Schrebler Carburetor Division for use in Curtis aircraft.  It was never 
> hung on a tractor.  The reason it hasn't changed in all these years is 
> because it ain't broke.
> 
> The pump is a lever operated diaphragm pump whose pressure is determined 
> by the force of a spring pushing on the diaphragm therefore the pressure 
> is self limiting and no other internal or external regulation is 
> needed.  The difference between the carburetor (5-6psi) and the fuel 
> injected (25-30psi) is the stiffness of the spring.
> By the way a wobble pump is a hand operated fuel pump generally used for 
> fuel transfer.
> 
> Larry Coen
> 
> ----- Original Message ----- From: "Jim Sower" <canarder at frontiernet.net>
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Sent: Friday, August 26, 2005 9:30 AM
> Subject: Re: REFLECTOR: engine driven fuel pump
> 
> 
>> It's a lever type wobble pump that pulsates a diaphragm.  Reed type 
>> check valves prevent back flow.  Excess pressure is vented back to the 
>> intake. Lever is driven by a cam.  Comes at us pretty much unchanged 
>> in the last 75 years or so.  I've seen fuel pumps that look exactly 
>> like the ones on our airplanes on a 1952 DeSoto.  Sort of like the 
>> Marvin-Dribbler carb - adapted from a 1920's farm tractor with iron 
>> wheels and no tires.  Hasn't changed much in the EIGHTY years since.
>>
>> Ain't technology wunnerful? ... Jim S.
>>
>>
>> kent wrote:
>>
>>> Thank you all (Ron, Chuck, Steve, Scott, TEC...) for your great 
>>> responses. I feel better knowing my engine driven fuel pump is at 
>>> least in the right ballpark.
>>>
>>> How do they work? I picture a geared drive but with an internal 
>>> pressure regulator independent of RPM, maybe with a relief valve. Or 
>>> is there some fancy mechanical device that compensates for RPMs but 
>>> turns out to be even more reliable?
>>>
>>> Kent
>>>
>>>
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