351,393. Cow-milkers. DINESEN, L., 2125, East Hennepin Avenue, Minneapolis, Minnesota, U.S.A. Feb. 17,1930, No. 5324. [Class 84.] In a pulsator of the kind wherein the pulsations in the teat cups are generated by a reciprocating piston which also partly rotates about its axis at the limits of its reciprocating movements, the piston is provided at the ends with swivelled heads which partake of the reciprocating movement but not of the part rotary movements of the piston. As shown, the pulsator cylinder 29, Figs. 3, 10 and 15, is detachably mounted on the lid a of the milk pail b and is provided in its base with a chamber 35 open to suction through a conduit 41. The chamber 35 communicates with the pail through a port 37 controlled by a ball valve 38 contained in a cage 39. The inner and outer compartments of the teat cups are connected to chambers in a claw, which chambers communicate respectively through a milk pipe n and a valve 23, Fig. 7, with the pail b, and through an air pipe p with a port 48 in the cylinder 29. The machine is adapted for milking two cows either simultaneously or independently, a milk pipe n and air pipe p being provided for each set of teat cups. The valves 23 are each provided with diametrically opposed ports 24, 25 which communicate through a chamber 26 provided with a transparent cover 27. The pulsator piston 42 is provided with heads 43, Fig. 10, rotatably mounted on hollow trunnions 44, and with a pin 45, Figs. 3 and 15, which projects through a slot 46 in the top of the cylinder 29 and coacts with a cam 66 carried by a bar 67, Fig. 5, mounted on studs 68 on the cylinder 29. Pawl-shaped abutments 69 loaded by torsion springs 70 are pivotally mounted on the studs 68 and bear against the cam 66, the pin 45 being thrust against the abutments at the end of the piston movements and thereby moved from one side to the other of the cam 66. The piston 42 is provided with a central port 58, Figs. 3 and 18, and with pairs of ports 54, 55, and 56, 57, Fig. 18, near the ends, which pairs of ports communicate respectively through ducts 59, 61 and 60, 62, Fig. 18, with the passages in the trunnions 44. In addition to the port 48 communicating with the outer chambers of the teat cups, the cylinder 39 has a port 49 opening into the suction chamber 35, ports 47, 50, 52 open to atmosphere and ports 51, 53 connected by a duct 64 provided with a port 65a controlled by a valve 65 and opening into the chamber 35. In operation, suction is transmitted through the conduit 41 to the pail b and through the valve 23 to the inner chambers of the teat cups. When the piston is in the position shown in Fig. 10, i.e. at the left hand end of the cylinder but before it is rotated, the left hand end of the piston is subjected to suction transmitted from the chamber 35 through the port 65a, left hand portion of conduit 64, ports 53, 56 and ducts 60, 62, the right hand end of the piston being subjected to atmospheric pressure through ports 50, 55 and ducts 59, 61, atmospheric pressure being also transmitted to the outer chambers of the teat cups through ports 47, 58, 48. When the piston is rotated, the conditions are reversed, the right hand end of the piston being then subjected to suction and suction being also transmitted to the outer chambers of the teat cups through ports 49, 58, 48.