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Date: Tue, 15 Aug 2006 19:03:25 -0500
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Emailing: DoorOpenLside.jpg
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Ed Anderson wrote:

> Hi Ben, good question concerning safety.   The door hydraulic 
> cylinders are single acting push-only.  A restrictor valve holds the 
> door open and a push of a button opens the value to let the fluid back 
> into the tank thereby lowering the doors.  The doors do not slam down 
> but do come down within 10-15 seconds (will have to time and see 
> exactly how long it takes).
>  
> But, regardless of double acting or single acting if a hose breaks you 
> could be in trouble as you suggest.  I intend to have 9-10 foot pipes 
> attached to main beam that when the door is open, I can pull down and 
> set to hold the door up.  That way should a hose fail the door won't 
> slam down.  These are 4000 psi bursting lines with 450 psi maximum 
> pressure - so hopefully I am not over stressing them.
>  
> It could certainly ruin your day to have that door come down on you.
>  
> Thanks for mentioning it - safety is always a high concern.
>  
> Ed


Hi Ed,

The door looks great. FWIW, you might be able to mechanically 'safety' 
the hydraulic cylinders with tubes over the cylinders themselves. If the 
business end of the cylinder is more or less flat, the tube would be big 
enough to slide over the cylinder but slightly shorter than the ram 
stroke & be hinged on the same pin that holds the ram to the door. When 
the ram extends, gravity pulls the free end off-center & it will prevent 
the ram from retracting. (not my idea; it's on some gas struts on some 
of our equipment at work)

More details available, but I'm too lazy to type them all. Give me a 
call if you're interested.

Charlie
601-879-9596 until 7:30 pm or 601-351-066 tomorrow morning after 2:00 AM