This section is from the book "Cassell's Cyclopaedia Of Mechanics", by Paul N. Hasluck. Also available from Amazon: Cassell's Cyclopaedia Of Mechanics.
For removing the sucker-valve of a lead pump a suckei-rod is necessary. This has a tapering threaded point which is passed down the barrel and screwed into the lead clack, which is then pulled off the sucker; the harpoon end of the rod is then passed through the latter, and lifted out. By warming the tail end of the pump barrel the sucker can be lifted out much more easily.