External check valve: Don't waste your money.
Posted: Sat Sep 04, 2021 5:42 pm
...making them difficult to use.
No. As usually sold, they are impossible to use. Why? Because they are sold with a modern chuck on them, not a Model T era chuck. How can a pump without a check valve possibly work? By relying on the valve in the tube stem to perform that function. A modern chuck has a center post that holds that valve open, rendering it inoperative. Install an old style chuck without a center post on your pump, and it works just as well as it did a hundred years ago.
http://dauntlessgeezer.com/DG115.html