Persuader
Persuader turns up in 2 fields: machine shop, electricians. Here is what it means to the people in each one.
Persuader in machine shop
Shop name for a hammer, usually a big one, used to convince a stuck part to move.
A tongue-in-cheek name for whatever striking tool gets a press fit, seized pin or stubborn bearing moving: a dead blow, sledge, brass bar or chunk of steel. Reaching for the persuader is the step after gentler methods fail, and the size of hammer chosen says a lot about the user's patience. Brass and dead blow persuaders are chosen when the part must survive.
"Pin's not moving, hand me the persuader, the brass one, I don't want to mushroom the end."
Persuader in electricians
Joking name for a hammer or big pry bar, the tool used when something needs convincing to fit.
Persuader is shop humor for a hammer, mallet or large pry bar, the tool reached for when a panel interior will not seat, a box will not shift or a stubborn fitting needs encouragement. Asking for the persuader signals that finesse has run out. Apprentices learn quickly that it is never used on breakers, meters or anything with a nameplate.
"Guts won't drop onto the studs, hand me the persuader, and I mean gently."