Traveler
Traveler turns up in 2 fields: heat treating, electricians. Here is what it means to the people in each one.
Traveler in heat treating
The paperwork that rides with a lot through the shop, recording each operation, furnace, time and result.
Job ticket that moves physically with the parts and gets signed or stamped at each station: receiving, wash, load, cycle start, at heat, quench, temper, hardness check and final inspection. It is the raw record behind the cert and the first thing pulled when a lot goes bad. Missing entries on a traveler are a routine audit finding.
"Write the at-heat time on the traveler, not on your glove, the auditor's here Thursday."
Traveler in electricians
One of the two conductors run between three-way switches, carrying power on whichever path is selected.
Travelers are the pair of conductors linking the two three-way switches that control a light from two places, landed on the brass-colored traveler terminals of each switch. One switch sends power down either traveler and the other picks it up from either one, so flipping either switch changes the state. Four-way switches go between the two three-ways and swap the travelers. Three-wire cable such as 14-3, with its red and black, is the usual way to run them.
"Red and black are your travelers between the three-ways, the white's the neutral, don't land it on a switch."