by Tom Gaylord
Writing as B.B. Pelletier
This report covers:
- Air intake and outlet valves
- The key to the test
- That’s not all
- I tested one, too
- More questions answered
- Maintaining consistency
- Three-stage hand pumps
- Summary
Today I will hopefully answer all your questions about the hand pump test that Dennis Quackenbush and I did many years ago. Remember — we were trying to determine how powerful the old big bore airguns had been. One part of that was knowing what kind of air pressure they used, and that is all we are looking at in this report.
Air intake and outlet valves
First I want to address a question from reader GunFun1. He asked about the pump’s air inlet valve. I told him there was no inlet valve. There is an air hole located at the top of the pump cylinder, and when the pump piston head rises past it, air is sucked into the cylinder — exactly the same as a conventional piston port 2-stroke engine. No valve is required. When the piston head drops below the air hole, the cylinder is sealed again and the piston is able to compress the air that’s now trapped inside.
