| 摘要 |
A pneumatic drive has at least one working cylinder composed of a pair of parallel stationary walls and a pair of walls which extend at right angles to the first pair and are movable relative thereto, towards and away from each other. This varies the volumetric content of the cylinder and changes one transverse dimension thereof. A piston is reciprocable in the cylinder and constructed of a plurality of sections which together define the piston surface that is exposed to the pressurized working medium of the drive. During the working stroke these sections move apart from one another so as to together define a piston surface of maximum area; during the idle (return) stroke the sections are moved together by an arrangement provided for this purpose, so that some of them are concealed behind or within others, thus reducing the piston surface to an area which may only amount to about 20% of the former area.
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