| 摘要 |
A compressed-gas-operated reciprocating-piston device, e.g. a concrete breaker, rock drill or chipping hammer, has a cylinder component of composite construction, comprising a rigid inner metal tube in which the piston reciprocates and a moulded outer sleeve of rubber or plastics material, e.g. polyurethane, which surrounds the tube over the majority of its length and is bonded thereto. The sleeve has three integral moulded longitudinal ribs in which are moulded longitudinal passages for transmission of compressed air to the cylinder interior. An outer tubular muffler of rubber or plastics material surrounds the composite cylinder component and defines a sound-reducing path for exhaust gas from the cylinder to the atmosphere. The exhaust gas is discharged into two spaces defined between two pairs of adjacent ribs of the sleeve within the muffler, these two spaces forming part of an expansion chamber in the muffler. This expansion chamber communicates with the atmosphere via a restriction, a second expansion chamber and a final duct leading to the exhaust opening in the muffler wall. The final duct is formed on the thickness of the muffler wall itself.
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