High Altitude and self contained air hammers

[John Larson]

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.

[Nakedanvil - Grant Sarver]

John, I had given that some thought. the check valve is actually on the outside of the machine on the far end of the bottom valve. easy enough to take it off and check it out. Sometime a new spring has been put in that might not be correct. Too weak or too short or not sealing in this case would do it.

[HammerHoyl]

Thank you guys for all your replies! This is excellent information and advice.

Naked anvil, thank you for the explination of the lower balance valve in the rear compression cylinder. This information is not illustrated well enough in the Krause publication. I stand corrected.

My "flap" valve does not flap at all. It is a stationary forged steel disc on a stem that bolts to the exhaust stem. Sounds like I may want to hinge the disc.

The check valve is in perfect working condition. It has a new spring and valve. I cannot hear leakage.

[Nazelhammers]

Thank you guys for all your replies! This is excellent information and advice.

Naked anvil, thank you for the explination of the lower balance valve in the rear compression cylinder. This information is not illustrated well enough in the Krause publication. I stand corrected.

My "flap" valve does not flap at all. It is a stationary forged steel disc on a stem that bolts to the exhaust stem. Sounds like I may want to hinge the disc.

The check valve is in perfect working condition. It has a new spring and valve. I cannot hear leakage.

If you have not found a solution to you hammer problem you can contact us directly for assistance if interested. We have some engineering files from the late 1930's or early 40's that address high altitude performance issues with Nazel Hammers. The issue is real enough that pneumatic engineers from Nazel studied the problem and tried to work out a satisfactory solution to it. It has been about 10 years since we've read over the specific files. It could take us a few days to find the documents amongst our records but we might be able to give you a clearer idea of what to expect from your hammer while using it in its current location.