Gradall 534B (9020-7317) Service Manual - Manual (Page 27)

Instructions - When it is desired to give instructions
to the operator other than provided by the
established signal system, all handler motions shall
first be stopped.
HAND SIGNALS
Standard Signals - When handler work conditions
require hand signals, they shall be provided or
posted conspicuously for the use of both signalman
and operator. No handler motions shall be made
unless signals are clearly understood by both
signalman and operator.
Special Signals - When signals for auxiliary
equipment functions or conditions not covered are
required, they shall be agreed upon in advance by
the operator and signalman.