【正文】 one type of oiling devices. The pressed air enters the lubricator, ejecting the oil lubricant into a spraying fog which flows with the pressed air into the ponents that need to be lubricated. Pressure reducing valve: Pressure reducing valve is one ponent of F. R. L. bination. It is used to reduce the pressure of pressed air from gas source to meet the pressure requirement of a given pneumatic system. The pressure after a pressure reducing valve is kept stable, avoiding both the influences of gassource pressure fluctuation and its output flow rate change. Like hydraulic transmission, the pressure regulating methods of pressure reducing valves incorporate: direct action type and pilot operated. Pneumatic Actuators Pneumatic cylinders Operations and functions: The operations and functions of mon cylinders are similar to those of hydraulic cylinders. Only some special cylinders are discussed in this section. (1) Diaphragm cylinders: A diaphragm cylinder is basically a large diameter, short stroke cylinder fitted with a diaphragm instead of a piston. The construction usually takes the form of a pair of shallow convex housings, with a diaphragm sandwiched between them and a 4 piston rod attached to the diaphragm. They are usually of singlerod type, either singleacting with spring return or doubleacting. Diaphragm cylinders are capable of generating very large forces with very short strokes and are monly called thrusters. The theoretical thrust available is equal to the product of the applied air pressure and effective diaphragm area. The stroke is normally limited to a maximum of about onethird of the cylinder diameter. Diaphragm cylinders are simple, concise in design, low cost, small leakage, easy to manufacture and maintain. But they have short strokes due to the limitation of the diaphragm deformation. Diaphragm cylinders are mainly used in pneumatic clamping devices and the working occasions with short stroke. (2) Airhydraulic cylinders: When outside load is large enough, there may occur poor stability to the movement of a unique pneumatic cylinder. This can be solved by an airhydraulic cylinder. Hydropneumatic working is achieved by mechanically coupling a pneumatic cylinder and a lowpressure hydraulic cylinder so that they have a mon movement normally initiated by pressed air applied to the air cylinder. Liquids have slight pressibility and air flow is easy to control, which leads to a stable movement and an adjustable speed. The normal configuration is backtoback mounting with a mon piston rod. The piston speed can be adjusted by throttle valve. Reservoir and check valve are used for oil pensation. In this circuit, the pneumatic cylinder only provides driving force and the stable movement depends upon the hydraulic cylinder by adjusting throttle valve. This circuit does not need any hydraulic source and thus is low in cost. In addition, it makes full use of pneumatic and hydraulic and thus finds many applications (3) Rodless cylinders: Recentlydeveloped rodless cylinders provide an ideal solution for long stroke applications. In one rodless design the cylinder barrel has a slit along the barrel and the piston in the barrel is connected directly through the slit to a mounting on the outside of the cylinder. Thus when the piston is moved by applying air on either side, the load connected to the external mounting is moved. The problem of providing a continuous and moving seal between the piston and sign handle long strikes effectively but can also accept lateral loading at the mounting point. This is an illustration of the construction of one type of rodless cylinder. The drive from the piston to the carriage is via a substantial drive tongue which passes through the barrel slot. This drive tongue forms the center part of this yoke which is incorporated in the carriage extrusion. The piston halves are pinned to the lower part of this yoke, joining the piston to the 5 carriage. The volume between the piston seals, containing the yoke, is at atmospheric pressure. The pressure and dust slot seals are unclipped and parted by cam shapes in the yoke within this nonpressurized section and by the advancing movement of the piston carriage assembly along the cylinder. After unclipping, the internal pressure seal slides under the lower part of the yoke adjacent to the piston halves, while the external dust seal slides over the upper part of the yoke within the carriage. The pressure and dust slot seals are then pressed together and reclipped by the spring roller assembly in the carriage and the ramp shape of the piston and by the retreating movement of the piston carriage assembly along the cylinder body. Thus the drive is taken up from the piston to the carriage through the slot as this assembly traverses the cylinder. (4) Impact cylinders: An impact cylinder is one arranged so that the speed developed is high enough for impact work, such as fing, piercing, etc