Direct translation from Russian is "lever", and it is based on the "law of the lever" by Archimedes. The idea is that, if you take a long rod, place it under a log and push using it as a lever, you will be able to move a very heavy piece of timber. The word "стяг" in this context is very localized. In ther place where I used to live, we called such rod as "вага" and never as "стяг". But the word "lever" is universal.

The complete phrase would sound as "Where a wise man would use a lever, he tried - with moans and groans - to roll it by hands"