HYDRAULIC DRIVE OF SELF-PROPELLED BOOM CRANE Russian patent published in 2003 - IPC

FIELD: lifting and transport engineering. SUBSTANCE: invention relates to hydraulic drive of large capacity self-propelled cranes with telescopic boom. Proposed drive contains load moment limiter with boom extension length pickup, supply source including at least one axial piston adjustable pump with power regulator and control pump, three-position distributor being essentially element of distributing unit with electrohydraulic proportional control, and tank. Control spaces of three-position distributor communicate with control pump and tank through main lines. Pneumohydraulic accumulator is installed in main line between control pump and control spaces of three= position distributor. Telescopic boom extension mechanism is furnished with two hydraulic cylinders. Rod of first hydraulic cylinder is hinge-secured on base section of telescopic boom, and housing of first hydraulic cylinder and rod of second hydraulic cylinder are hinge-secured on one of ends of extensible middle section of telescopic boom. Housing of second hydraulic cylinder is hinge-secured on extensible front section of telescopic boom. Said hydraulic cylinders, each, are furnished with brake and check valves through which piston spaces of hydraulic cylinders communicate, respectively, with supply source through three-position distributor. Rod spaces of hydraulic cylinders are interconnected and connected with control space of brake valve of second hydraulic cylinder. Hydraulic drive contains also two-position distributor with electrohydraulic control communicated with control pump, and electromagnetically-controlled two-position distributor. Said two- position distributors are made for electric communication with boom extension length pickup. Control space of first hydraulic cylinder brake valve can communicate through electromagnetically-controlled two-position distributor in one position with main line connecting rod space of first hydraulic cylinder through three-position distributor with supply source and in other position, with drain main line communicating with tank. Piston space of second hydraulic cylinder can communicate through electrohydraulically-controlled two-position distributor in on of its positions with tank through additionally introduced check valve, and in other position, with supply source through three-position distributor. EFFECT: improved reliability of drive at provision of successive extension of several sections of telescopic boom. 2 dwg