Efficient and safe production processes in sustainable agriculture and forestry XXXIV CIOSTA CIGR V Conference 2011 29 June -1 July 2011 Vienna – Austria University of Natural Resources and Applied Life Sciences Development of a Computer Controlled System for the Evaluation of the Milking Machine Pulsator and Liner R. Roşca 1 , I. Ţenu 1 , P. Cârlescu 1 , E. Rakoşi 2 1 University of Agricultural Sciences, M. Sadoveanu 3, Iaşi, 700490, Romania, e-mail: rrosca@uaiasi.ro 2 Technical University, bvd. D. Mangeron 61-63, Iasi, 700050, Romania, e-mail: edwardrakosi@yahoo.com e-mail of corresponding author: rrosca@uaiasi.ro Summary A computer-controlled system was developed in order to evaluate the working characteristics of the components (teatcups, pulsators) of a mechanical milking machine. The system contains a pulse generator, allowing the adjustment of both the pulsation rate (between 10 and 120 cycles/min) and extraction to massage ratio (between 10 and 90%), and a cyclic pressure indicator, which monitors the pressure applied to the teatcup short pulse tube. Two types of pulsators were tested in order to evaluate the precision and parameters of the developed systems: an electromagnetic pulsator and also a STIMO IQ one. After the reliability of the system was confirmed, three types of milking teatcups were tested, in order to investigate the effect of the liner type over the pulsation cycle (duration of phases and pulsation ratio), when a hydropneumatic pulsator is used. Key words: milking machine, pulsator, milking to massage ratio Introduction We have been milking cows with the same basic assembly of teatcup shell and liner for the past 100 years. The basic concepts of milking cows quickly, cleanly and gently have, indeed, remained unchanged. There has been a steady advance, however, in our understanding of the milking process from the perspective of the cow and the machine. One of the major advances in mechanical milking was the introduction of the pulsation principle. Pulsation is defined as "cyclic opening and closing of a teatcup liner" [CowTime Quick Note 4.3, 2003]. The development of pulsation was a major turning point in the adoption of mechanical milk harvesting systems, the main purpose of pulsation being to limit the development of congestion and edema in the teat tissues during machine milking. In addition to, or because of, this primary function, pulsation helps to: • maintain a high rate of milk flow from the teat within each pulsation cycle; • reduce the rate of new mastitis infections; • counteract the possible ill effects of teat congestion or the level of discomfort or pain experienced by the cows; • stimulate good milk letdown. An example pulsation cycle (at a pulsation rate of 60 cycles/min) is shown in Figure 1. Milk starts to flow from the teat during the a-phase (or opening phase) of pulsation. Typically, milk will start flowing at a time corresponding to a point about 25 – 50% up the a-phase curve. The exact time at which milk flow starts depends mainly on the mounting tension and wall thickness of the liner. Milk flow continues throughout the b-phase (the open phase) and into the first part of the c- phase (the closing phase). Milk stops flowing at a time corresponding to a point about 50 – 75% down the c-phase curve and the teat canal remains closed throughout the d-phase and into the first part of the opening phase [CowTime Quick Note 4.3, 2003]. Both field experience and research have shown that a relatively narrow range of pulsation rates and ratios is required to ensure good teat-end health, good udder health and to optimize milking speed. The preferred range for pulsation rate is about 55 to 65 cycles/min. The preferred range for pulsator ratio (a+b)/(c+d) is about 55:45 to 65:35. At a pulsator ratio of 80:20, the peak