John Larson Posted January 15, 2010 Share Posted January 15, 2010 The Nazel's bottom air circuit valve system (as I recall without referencing my literature) provides a check valved by-pass (around the bottom throttle valve) to allow the tup to pump up when the treadle is released. That circuit detail suggests that the check may not be fully efficient. If it is working properly the pumping up should occur, but with a few more pump cylinder strokes. Yes, the reduced air density can be exposing this and at lower altitude it may have been less obvious. BTW, in principle this air duct could be tested with a shop air hose connection. If the check valve is leaking, it would probably be audible and maybe the hammer head rise could be tested at various line pressure settings. I agree with idea of a lighter weight top die. Pretty darn clever IMHO. To avoid undue expense just to test the idea, try leaving the dies as originally dimensioned but use an alternative lighter material. Got a block of aluminum, delrin plastic, or a piece of good oak? This way you won't accidentally use a short top die with the original height bottom die and injure the machine via piston-to-cylinder bottom cap collision. Even more simply, remove the top die and use a compensating wood block on top of the bottom die. That way the test takes only a few minutes and doesn't require fabrication. Use tongs to hold the wood block. Quote Link to comment Share on other sites More sharing options...
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