| 摘要 |
An indicating device for a milking apparatus indicates regular or irregular working of each of the four teat cups. The device is attached to a twin electro-pneumatic pulsator which comprises two vertical solenoid-operated units (20, 21, 22), each serving to expand and contract the expandable linings (2) of two teat cups respectively, by alternately admitting atmospheric pressure and vacuum pressure to the teat cups. The device consists of a transparent, hollow cylinder (31) horizontally positioned between the two valve units and pneumatically communicating at each end with the air inlet duct (27) of either valve unit, and of a free piston (33) reciprocatingly movable in the cylinder (31). The alternate change of air pressure in the inlet ducts drives the piston to and fro, and a difference in air pressure in the two ducts, as a result of the teat cups not working uniformly, is indicated by the distance at which the piston stops from the respective end of the cylinder during its reciprocating movement therein.
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