REMOTELY OPERABLE LATCH AND LOCKING PIN FOR A MULTI- SECTION BOOM INCLUDING A MANUAL FLY SECTION

摘要

REMOTELY OPERABLE LATCH AND LOCKING PIN FOR A MULTI-SECTION BOOM INCLUDING A MANUAL FLY SECTION A multi-section hydraulically operated telescoping crane boom includes a manual fly section (23) which may be safely extended and retracted, securely latched in the extended position and pin locked by remote operation of a biased hydraulically powered latching plunger (33) and a biased cooperative hydraulically powered locking pin (52) both embodied in a static hydraulic circuit which includes in one form a pressure fluid circuit safety interlock portion (Fig. 4) with a pressure-responsive indicator(123) to indicate when the latching plunger (33) is engaged (48), and in another form an electrical switch circuit safety interlock portion (Fig. 7) controlling the hydraulic circuit, with an electric switch(131) operated indicator(159) to indicate when the latching plunger (33) is engaged (48). The safety interlock portions of both circuits for the cooperative latching plunger (33) and locking pin (52) prevent their operation in improper sequence so one is engaged at all times before the other is disengaged.