Measuring Milking Machine Liner Slips

¹ Department of Dairy and Animal Science
² Electronic Design Services, The Pennsylvania State University, University Park 16802

Liner slip or rapid air leakage past the mouthpiece of the milking machine liner has been identified as a cause of new infection in the bovine mammary gland. A device has been developed to differentiate and count the abrupt losses of milking vacuum due to liner slips from the many other vacuum fluctuations that occur in the clawpiece during milking. A Microswitch® transducer converts vacuum to an analog direct current output voltage. An electronic comparator monitors the transducer output and closes a gate switch to a digital counter when a large, high speed vacuum change occurs. This vacuum change is initially set to activate the initial slip counter when the vacuum change is greater than 8 kPa in less than .25 s. The magnitude threshold is adjustable; however, the time base is fixed. The counter is then blocked from responding to a new signal for 5 s, because subsequent large fluctuations (squawks) may occur following the initial slip. A second major fluctuations digital counter responds to all large fluctuations beyond an adjustable vacuum threshold without a time base element.

Key Words: liner slip • vacuum • milking machines

Submitted on April 20, 1989
Accepted on October 2, 1989