| 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 thge atmosphere. The exhaust gas is discharged into spaces defined between adjacent ribs of the sleeve within the muffler, these spaces forming part of an expansion chamber in the muffler. This expansion chamber communicates with the atmosphere either directly through exhaust ports or via a restriction and a second expansion chamber to a final duct leading to an exhaust opening in the muffler wall.
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