Hitachi ZW 310-6 Operator's Manual page 199

Articulation Stopper (Lock Bar)
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WARNING:
 Before servicing or transporting the machine, be
sure to engage lock bar (1).
 Before operating the machine, be sure to
disengage lock bar (1) from front chassis (4) and
fasten the lock bar to rear chassis (2) with β-form
lock clip (3).
Articulation lock bar (1) locks the front and rear chassis to
prevent articulation between the front and rear chassis
when servicing or transporting the machine.
OPERATOR'S STATION
1-137
90Z7-1-136-1
90Z7-1-136-2