| 摘要 |
A simple, rugged, compact and reliable apparatus (20, 54, 55, 56, 58, 64) for cutting trees (24), vegetation and other objects, together with methods for operating such apparatus, are provided wherein a cutting blade (22, 22''), constrained for movement along a cutting path generally transverse to the tree (24) or other object being cut, is coupled to a piston/cylinder type accumulator (42/44, 42'/44', 42''/44'') within which a compressible medium defines a source of stored potential energy. In the various embodiments shown, the accumulator is disabled until such time as its piston (42, 42', 42'') is shifted past its top dead center position so as to fully compress the compressible medium contained therein for maximizing the amount of stored potential energy; and, a positioning mechanism comprising a second piston/cylinder combination (31/32) is provided for selectively shifting the accumulator piston (42, 42', 42'') towards and past its top dead center position so as to permit the fully compressed potential energy storage medium to rapidly expand and, through the accumulator piston, drive the cutting blade (22, 22'') through its cutting patch with inertial forces generated by the driven components serving to partially recompress the compressible potential energy storage medium upon completion of the cutting stroke, and wherein the positioning mechanism is used to return the accumulator piston (42, 42', 42'') to its top dead center position upon dissipation of the inertial forces and thus completing the compression of the compressible medium preparatory to the next cutting stroke. One-way clutches (30, 41) and/or a latching mechanism (66, 68) are employed to control movement of the driven components.
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