TELESCOPIC BOOM Russian patent published in 2001 - IPC

FIELD: load-lifting equipment. SUBSTANCE: proposed telescopic boom has lower section 1 and telescopic middle section 2 and upper section 3. Middle section accommodates middle and upper section telescoping drive made in form of two hydraulic cylinders 4 and 5 connected to each other by housing, rods of cylinders being directed to opposite sides. Rod of one hydraulic cylinder is secured on lower section, and rod of other cylinder, on upper section. Equalizing mechanism sheaves are installed on rear end face of middle section and on inner part of upper section. Cable reeved in sheaves is secured in tensioner 11. Hydraulic system has pilot-controlled check valve whose control space communicates with rod space of hydraulic cylinder. Rod of this hydraulic cylinder is connected to lower section. Lock space of pilot-controlled check valve is connected with piston spaces of both hydraulic cylinders. Rod space of hydraulic cylinder whose rod is connected to upper section communicates with pilot-controlled check valve, through non return valve, with rod space of hydraulic cylinder whose rod is connected to lower section. EFFECT: improved reliability and convenience of servicing. 1 dwg