Liner Assembly Research Articles

Wear and film formation in the presence of methanol and formic acid

Increased wear in methanol fuelled engines has been observed, especially at low operating temperatures. Combustion intermediates, for instance formic acid, are believed to promote wear in the piston ring/cylinder liner assembly. In this study, tribological effects of methanol and formic acid were investigated in a model system. The study was focused on the running-in process under normal conditions and how the running-in was affected by the presence of methanol and formic acid in oils with different lubricant additives. The study showed that a tribosystem with the anti-wear additive ZDDP (zinc dialkyldithiophosphate) had the ability to redistribute the surface layer. After an initial phase of large wear, this redistribution process resulted in a surface film with excellent wear resistance. Adding methanol and formic acid contaminants to this lubricant disturbed the film formation process and a higher steady state wear was observed. A more fully formulated lubricant, with detergent and dispersant, could better withstand these contaminants even though a rise in the steady state wear rate was found in experiments performed at room temperature.

Milking Characteristics of Teatcups with Reduced Liner Wall Movement

To evaluate effects of reduced liner wall movement on milking performance and pressure gradient across the short milk tube, we developed and compared four experimental teatcup assemblies to a conventional unit. These assemblies were 1) a conventional liner with restricted liner wall movement, 2, 3) two partial liners of different lenghts, and 4) a partial liner equipped with a mouthpiece adapter. In three of the four experiments, milking performance was evaluated. In the fourth experiment vacuum conditions and reverse pressure gradients across the short milk tube were measured.The long partial liner resulted in longer milking time and lower peak milk flow rate than the control (7.6 versus 5.9min and 2.5 versus 3.2 kg/min). The difference in milking time was eliminated when the mouthpiece adapter was included. Characteristics of milking performance of the restricted liner were similar to the control with the exception of peak milk flow rate, which was decreased for the restricted liner (3.3 versus 3.6 kg/min).Reverse pressure gradients were measured across the short milk tubes of the conventional liner (−4 kPa) and the restricted liner (−2 kPa). Reverse gradients were practically nonexistent for the partial liner assemblies.