Abstract: A teat cup is provided with a sensing diaphragm in the mouth piece and is connected by a linkage to a valve operating on the air line inlet to the pulsator chamber. Variation of the vacuum level within the ring chamber causes the valve in the air line to open and close to thereby affect the vacuum level applied to the pulsator chamber. A method of milking is described in which sensing of the vacuum level within the ring chamber enables control of the vacuum level applied to the pulsator chamber so that a high vacuum within the ring chamber, for example when a teat cup is first applied to an unstimulated teat, will cause the vacuum in the pulsator chamber to drop thereby closing the inflation to close off communication between the milk line and the teat allowing the teat to be stimulated to let down milk.