Tham khảo tài liệu 'lubrication fundamentals 2011 part 13', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | same temperature. These temperatures although higher than those reached in actual practice since some of the heat is removed by cooling the cylinder walls are indicative of the temperatures that must be considered when selecting compressor lubricants. I. RECIPROCATING AIR AND GAS COMPRESSORS Reciprocating compressors are used for many different purposes involving mild conditions to extremes of pressure and volume requirements. As a result a great variety of designs are commercially available. Most reciprocating compressors are of the single- or two-stage type with smaller numbers of multistage machines three four or more stages such as shown in Figure . From the lubrication point of view single- and two-stage machines generally are similar while multistage units may have somewhat different requirements depending on pressures temperatures gas conditions and the size and speeds of the pistons. The principal parts common to all reciprocating compressors are pistons piston rings cylinders valves crankshafts connecting rods main and connecting rod bearings crankpin bearings and suitable frames that generally contain the lubrication system. Double-acting machines which compress on both faces of the pistons refer to Figure require piston rods packing glands crossheads and crosshead guides the connecting rods are connected to the crossheads by crosshead pins. Crossheads and associated parts are also used in some multistage single-acting compressors but the majority of singleacting compressors are of the trunk piston type with the connecting rods connected directly to the pistons by piston pins wrist pins . For lubrication purposes all parts associated with the cylinders including pistons rings valves and rod packing on double-acting machines are considered to be cylinder parts Figure . All parts associated with the driving end including main connecting rod crosshead pin or wrist pin bearings and crankshaft and crosshead guides are considered to be running .
