Mechanical Engg Simple Notes ,Solved problems and Videos

Explain with neat sketch (position based ) working of sequencing circuit for two double acting Air cylinders. Pneumatic double acting cylinders can be operated sequentially using a sequence valve or by using position based method. In pneumatics, use of sequence valve is not popular. Position based sequencing is possible using roller operated DCV or solenoid operated DCV. Various components required for Position based sequencing using roller operated DCV are as follows. I. Double acting cylinder - 02 Nos. II. 3/2 roller operated DCV – 02 Nos. III. 4/2 or 5/2 DCV – 01 No. IV.

.Draw and Explain pneumatic meter in circuit to control of speed extension. In meter in pneumatic circuit flow control valve with check valve is fitted between DCV and actuator. For speed control of actuator during extension stroke, FCV with check valve is fitted on piston side of the actuator as shown in figure. With a meter-in circuit, fluid enters into the actuator at a controlled rate. Pneumatic circuit diagram for meter-in flow-control circuit is as shown in figure. In this circuits, the rate of flow of compressed air into the cylinder is controlled by flow control

List the Factors to be considered for selecting the pipe while designing pneumatic system. Give specification of pipes for the pneumatic system. Factors to be considered while selecting the pipe for pneumatic system 1. Pressure of compressed air in the line. 2. Total flow rate per unit time through the line. 3. Permissible pressure drop in the line. 4. Type of tube material and type of line fittings. 5. Length and diameter of tube or other pipelines. 6. Working environment. Pipe Size Specifications: Generally pipe size is specified in three ways 1.

) Explain with neat sketch working of variable displacement vane pump. In a hydraulic system the flow rate of the pump needs to be variable this can be easily achieved by varying the rpm of the electric motor. Other method is displacement of a vane inside the pump and therefore its delivery is proportional to the eccentricity between the rotor axis and cam ring. Changing the geometric position of the ring relative to the rotor center will change the delivery volume as per system need. Main components of the vane pumps are: 1. Hardened cam ring 2. Rotor 3. Vanes 4.

To start, stop and change the direction of motion of a Single acting cylinder. (Clamping of Job)

Varying the rate of flow of oil will vary the speed of the actuator. Speed control is possible using meter in circuit, meter out circuit, bleed off circuit or by placing flow control before the DCV. Speed control of bi-directional air motor: Bi-directional air motor rotates in clockwise as well as anti-clockwise direction. The speed of bi-directional motor is controlled as shown in fig. The speed control of motor by using variable two flow control valves having built-in check valve and 4x3 DC valve having zero position or central hold position with Pilot S1 and S2.

Actuator - Actuators are those components of hydraulic / pneumatic system, which produces mechanical work output. They develop force and displacement, which is required to perform any specific task. An actuator is used to convert the energy of the fluid back into mechanical power.