Cheater bar
Cheater bar turns up in 2 fields: valves, machine shop. Here is what it means to the people in each one.
Cheater bar in valves
A length of pipe slipped over a wrench or valve handle to gain extra leverage on something stuck.
On valves, a cheater bar is the fastest way to bend a stem, crack a handwheel, gall a stem nut or crush a seat by overclosing. Plants often ban them in favour of proper valve wrenches with known length, or require a gear operator on valves that need more torque. Nearly every crew keeps one leaning in a corner anyway.
"Put the cheater bar down, if it takes that much to shut, the seat's full of junk and you'll just bend the stem."
Cheater bar in machine shop
A length of pipe slipped over a wrench handle for extra leverage on a stuck fastener.
A pipe or tube used to extend a wrench, breaker bar or vise handle, multiplying the force a person can apply. It breaks loose seized bolts, and it also bends wrenches, cracks sockets, strips vise screws and snaps studs, because the tool was never rated for that load. Using one on a machine vise handle is a firing offense in some shops.
"Don't put a cheater bar on the vise handle, if it won't hold the part by hand, your setup's wrong."