Tham khảo tài liệu 'mechanism of steam engines part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | MECHANISM OF STEAM ENGINES CHAPTER I GENERAL DISCUSSION OF A RECIPROCATING STEAM ENGINE 1. There are a great many types of reciprocating steam engines differing widely in size and general design. Certain fundamental principles of design and method of action are common to all however. The parts of a reciprocating engine may be divided into three main groups 1. Stationary parts frame cylinder bearings . 2. Piston piston rod crosshead connecting rod crank shaft and flywheel to which the steam imparts motion. 3. Valve mechanism which controls the supply of steam. The most direct way to gain familiarity with the parts and with the principles of operation is to study in detail a simple example. 2. Description of a Simple Engine. Fig. I represents a small reciprocating engine of the type known as a plain-slide-valve engine. Directly on the concrete or masonry foundation rests the frame z carrying in suitable bearings near one end the engine shaft Ỡ while bolted to it at the other end is the cylinder E. The cylinder is closed at the ends by heads and is covered or lagged with some material which is a good non-conductor of heat to prevent too rapid radiation. In the cylinder is the piston F which moves from one end to the other under the influence of steam pressure. There must be no leakage of steam past the piston and it is made steam tight by two split rings in grooves around the piston which spring outward and press against the cylinder walls. The piston is rigidly attached to the piston rod G the latter being attached at the other end to the crosshead H. Where the piston rod passes through the cylinder head leakage of steam is prevented by packing. The crosshead slides back and forth between the guides z which prevent any tendency to bend the piston rod. I 2 MECHANISM OF STEAM ENGINES The motion of the crosshead is carried to the crank pin A by means of the connecting rod J the latter being attached to the crosshead by the wrist pin or crosshead pin B. The connecting .