Pressure gauge (English Name: pressure gauge) is a kind of instrument which uses elastic element as sensitivity to measure and display higher than the environmental pressure. It is widely used, almost covering all fields of industrial process and scientific research. Heat supply network, oil and gas transmission, water supply and gas supply system, car repair workshop, everywhere. The muffler of diesel engine, especially in the process of industrial process control and technical detection, is more and more widely used because of its high mechanical strength and easy production. In the industrial process control and measurement, the mechanical pressure gauge has been widely used in various industrial fields because of its high mechanical strength, exhaust muffler and convenient manufacturing and low cost. The commonly used elastic sensing elements of mechanical pressure gauge are spring tube (bellows), diaphragm, bellows (ship type ash hopper fan) or bellows. The elastic deformation of elastic element under the action of medium pressure is amplified by gear transmission mechanism (movement), and the corresponding pressure value is indicated by the pointer on the dial.