BINDLE STIFF
A hobo who carries a bedroll or a bundle of possessions
AIR MONKEY
A mechanic who repairs the air brakes of a railroad
HOBO
A migratory worker
DOLLY FLOPPER
A brakeman or switch-tender
PIN PULLER
A conductor
KNUCKLE
Part of a couple that locks
PADDLE
Slang for a semaphore-flag signaling system