In the working stroke of piston 1, when it strikes the hammer head, compressed air is admitted through channel a to the right end of the cylinder. From the left end, air is forced out through channel d, annular groove b and port f into the atmosphere. At the end of the working stroke, compressed air, passing along channel g, shifts slide valve 2 to the right and is admitted through channel d to the left end of the cylinder, effecting the return stroke of piston 1. From the right end, the air is discharged through port e. At the end of the return stroke, port e is closed by piston 1, air in the right end of the cylinder is compressed and it shifts slide valve 2 to the left. This begins the working stroke again.
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