Control for a milker unit support

In a support for positioning a milker unit beneath a cow, the support having

• a base,
• a shaft vertically movably mounted on the base,
• an arm extending from the shaft and being positionable beneath a cow,
• a supply of air under pressure, and
• means for applying pressure from said supply of air to hold the shaft at a desired position,
• an improved control for automatically adjusting the vertical position of the support so that the weight of the milker unit is continuously applied to the cow's teats, comprising:
• a first valve interconnected between the air supply and the shaft, the first valve being movable between a normally closed position and an open position, the first valve in the open position thereof decreasing pressure applied to said shaft whereby the shaft is permitted to lower;
• a second valve interconnected between the air supply and the first valve, the second valve being movable between a normally closed position and an open position, the second valve in the open position thereof permitting air from the supply to move the first valve to the open position thereof;
• and
• means for mounting the second valve on the support so that force applied to the arm as by the weight of the milker unit moves the second valve to the open position thereof to lower the arm.