| 摘要 |
A telescopic arm assembly (15, 115) of a deep excavator comprises top, middle and base arms (6, 9, 10; 106, 109, 110). A bucket (13) is suspended from the top arm (10, 110). A working unit (20, 120, 180) is mounted within the middle arm (9, 109) and comprises two hydraulic cylinders (21, 22; 121, 122; 181, 182) arranged in parallel. The cylinder rod (23, 124, 184) of one hydraulic cylinder is coupled to the base arm and the cylinder rod (24, 123, 183) of the other hydraulic cylinder is coupled to the top arm (10, 110). It is possible to extend and contract each arm of the telescopic arm synchronously at high speed compared with a conventional deep excavator having a single hydraulic cylinder. The oil pressure which flows out from the discharge chamber of each hydraulic cylinder can be merged into the oil under pressure for extending each hydraulic cylinder so that the amount of oil to be supplied to the pressure chamber is increased. <IMAGE> |
