-=> BOB KLAHN wrote to WAYNE CHIRNSIDE <=-

 BK>  Ok, I've waited long enough.

 BK>  ...

 WC> They've got those domes already down there two of them!
 WC> They've got the drilling mud already right there.

 WC> You put the larger dome over the wellhead and feed the
 WC> drilling mud into the dome.

 WC> The circumference of the domes size being larger than the
 WC> wellhead gives you the equivalent of mechanical advantage
 WC> but via hydraulics in direct proportion to the differences
 WC> in the area between the area of the pipe to the dome.

 WC> It's EXACTLY how a hydraulic jack works.

 BK>  Actually, no. That's exactly opposite to how a hydraulic jack
 BK>  works.

 BK>  The mechanical advantage comes from the small piston having
 BK>  pressure put on it, transferred through the fluid to the large
 BK>  piston.

 BK>  Not from the large to the small.

 BK>  If you have a one square inch piston, and put 100 lbs of
 BK>  pressure on it, like a 100 lb weight sitting on it, the pressure
 BK>  is transmitted to all parts of the fluid as 100 PSI. If you have
 BK>  a 5 sq in piston in the circuit, that 100psi is transferred to
 BK>  all 5 square inches. For a total pressure of 500 lbs.

 BK>  There is still no free lunch, that one sq inch piston has to
 BK>  move the fluid driving that 5 sq inch piston. To do that it has
 BK>  to move 5 times as much fluid as the surface of the 1 sq in
 BK>  piston. A bit simplified.

 BK>  IOW, the 1 sq in piston has to move 5 inches for each inch the 5
 BK>  sq in piston. To lift your care 10 inches the small piston has
 BK>  to move 50 inches.

 BK>  Ok, it can't move 50 inches, so it moves 1 inch 50 times. The
 BK>  jack has a one way valve, which allows you to move the weight by
 BK>  moving the piston a little bit, then pulling back and doing it
 BK>  again. Same length of stroke, but over multiple passes.

 BK>  Oh, and finally, that mechanical advantage is mechanical to
 BK>  mechanical through the hydraulic fluid. It doesn't work at all
 BK>  with hydraulic to hydraulic. Then the 100PSI is just transfered
 BK>  equally throughout the system, no gain at all anywhere.

Darn, you're right.

Getting too old.
 
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