Lab 5 Directional Control Valves

doc

School

Centennial College *

*We aren’t endorsed by this school

Course

121

Subject

Mechanical Engineering

Date

Apr 3, 2024

Type

doc

Pages

11

Uploaded by DeanViper3618

Report
Industrial Hydraulics for Colleges Industrial Hydraulics for Colleges Intro Intro Lab Title: Directional Control Valve Circuits Student Name : Section: Instructor: Paul Bligdon Centennial College: Paul Bligdon Page 1
Industrial Hydraulics for Colleges Industrial Hydraulics for Colleges Intro Intro Parker’s Training Bench DCV Circuit This hydraulic lab introduces concepts in the control and operation of a directional control valve as it applies to a manually operated valve Students will examine the operation of a typical hydraulic circuit with close attention being paid to the functioning of a directional control valve as it applies to the conservation of energy during machine idle. This lab exercise reinforces the theory studied during the lecture period and classroom assignments. Learning Outcomes At the conclusion of this lab, you will be able to: Work in compliance with the Ontario //Health and Safety Act and the College’s Safety Standards during the performance of the lab exercise. Sketch the lab’s manual DCV circuit using ANSI symbols Reference both System Pressure and Flow Rate at various points in the circuit Describe the energy saving effect of the open center condition Install and operated both the solenoid and manually operated DCV Centennial College: Paul Bligdon Page 2
Industrial Hydraulics for Colleges Industrial Hydraulics for Colleges Intro Intro Procedure: 1. Turn the power distribution panels electrical disconnect switch to the “on” position. 2. Release the emergency stop push button 3. Ensure that the pressure compensator’s vent handle is in the passing position (horizontal) 4. Depress the training bench start button. 5. Turn the vent handle to the non-passing position.(vertical) 6. Adjust the relief valves adjusting knob until the system pressure seen on PGM gauge reads 1000 pisg. 7. Depress the training bench “off” push button. 8. Depress the emergency stop button. 9. Turn the power distribution panels electrical disconnect switch to the “off” position. 10. Connect a hose from the pressure manifold block to the inlet port of the flow meter 11. Connect a hose from the outlet port of the flow meter to the “P” port of the solenoid operated directional control valve 12. Install a hydraulic tee on the piston port of the horizontal cylinder. 13. Connect a hose from the “A” port of the directional control valve to one leg of the tee located on the piston port of the cylinder 14. Install a portable pressure gauge on the other leg of the tee located on the piston port of the cylinder 15. Install a tee on the rod port of the cylinder 16. Connect a hose from the one leg of the tee located on the rod port to the “B” port of the directional control valve 17. Install a portable pressure gauge on the other leg of the tee located on the rod port of the cylinder Centennial College: Paul Bligdon Page 3
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Industrial Hydraulics for Colleges Industrial Hydraulics for Colleges Intro Intro 18. Connect a hose from the “T” port of the directional control valve to the return manifold block. Note: Observe the ANSI symbol located on the bench which depicts the function of the directional control valve. “A” This position directs the pump’s flow through the DCV from “ P port to the “ A ” port. The flow then travels to the piston port of the cylinder allowing the cylinder to Advance. The flow returning from the rod side of the cylinder returns through the DCV from “B” to “T” port. The solenoid that shifts the DCV to this position is called the “A” solenoid. “B” This position directs the pump’s flow through the DCV from “ P port to the “B A ” port. The flow then travels to the rod port of the cylinder allowing the cylinder to return Back . The flow returning from the rod side of the cylinder returns through the DCV from “B” to “T” port. The solenoid that shifts the DCV to this position is called the “B” solenoid. The center position of the DCV has all of the ports blocked allowing the cylinder to be stopped at any position in its travel. To achieve the Center Position de-energized both solenoids and the centering springs will shift the DCV to it center position “A” position “B” position Center Position
Industrial Hydraulics for Colleges Industrial Hydraulics for Colleges Intro Intro 20. Turn the power distribution panels electrical disconnect switch to the “on” position. 21. Release the emergency stop push button 22. Ensure that the pressure compensator’s vent handle is in the passing position (horizontal) 23. Depress the training bench start button. 24. Turn the pressure compensator vent handle to the non-passing position.(vertical) 25. Using the solenoid selector switch; turn the selector to the “A” position, and observe if the cylinder rod Advanced. 26. Using the solenoid selector switch; turn the selector to the “B” position, and observe if the cylinder rod came Back 27. Return the selector switch to its middle position. 28. Advance the cylinder rod; however this time, return the selector switch to its middle position several times while the cylinder rod’s is advancing. 29. Repeat this same step (29), only this time during the cylinder rod retract cycle. 30. Place your observations into the table below. Centennial College: Paul Bligdon Page 5
Industrial Hydraulics for Colleges Industrial Hydraulics for Colleges Intro Intro Solenoid Selector Position Record the DCV flow paths ( ie: P - A and B - T) Cylinder Motion “A” Pressure comes to our circuit from A port Extending “B” Pressure comes back to the tank Retracting Center There is no movement in this situation Nothing 31. With the cylinder rod positioned half way out and the selector switch in the middle position, manually try to push the cylinder back into the cylinder. 32. Depress the training bench “off” push button. 33. Depress the emergency stop button. 34. Turn the power distribution panels electrical disconnect switch to the “off” position. 35. Transfer all four hoses connected to the solenoid directional control valve to the same ports on the manually operated directional control valve. 36. Using the DCV lever; position the DCV in its “A” position, and observe if the cylinder rod Advanced. Note : the lever must be held in that position for the cylinder to continue its motion 37. Using the DCV lever; position the DCV in its “A” position “B” position, and observe if the cylinder rod came Back. Note : the lever must be held in that position for the cylinder to continue its motion 38. Release the DCV lever and the centering springs will place the valve in its middle position switch to its middle position. Centennial College: Paul Bligdon Page 6
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Industrial Hydraulics for Colleges Industrial Hydraulics for Colleges Intro Intro 39. Advance the cylinder rod; however this time, release the lever which will return the valve to its middle position several times while the cylinder rod’s is advancing. 40. Repeat this same step (39), only this time during the cylinder rod retract cycle.Place your observations into the table below. Lever Position Record the DCV flow paths ( ie: P - A and B - T) Cylinder Motion “A” The pressure comes to our circuit from A port Extending “B” The pressure goes back to the tank Retracting Center The cylinder is extending by lower speed because all the ports are connected together. Extending 41. With the cylinder rod positioned half way out and the lever in the middle position, manually try to push the cylinder back into the cylinder. 42. Retract the cylinder rod. 43. Depress the training bench “off” push button. 44. Depress the emergency stop button. 45. Turn the power distribution panels electrical disconnect switch to the “off” position 46. Remove all hydraulic hoses, tees and gauges from the training bench and return them to their storage area. Centennial College: Paul Bligdon Page 7
Industrial Hydraulics for Colleges Industrial Hydraulics for Colleges Intro Intro Review Questions. 1. Describe the solenoid directional control valve used in this circuit. Position Way Activated Centered Center Condition 2. Describe the manual directional control valve used in this circuit. Position Way Operated Centered Center Condition 3. The traditional naming convention for solenoids Sol A is derived from the following: a. Identifies which solenoid when energized places the tank port connected to the A cylinder b. Identifying which solenoid when energized places the pressure port connected to the A cylinder c. Sol A is always on the right side of the valve d. It doesn’t matter Centennial College: Paul Bligdon Page 8 When answering the review questions always refer to the ANSI schematic drawing for the lab and observation recorded in the table to assist you in answering the questions
Industrial Hydraulics for Colleges Industrial Hydraulics for Colleges Intro Intro 4. When connecting the cylinder to a solenoid activated, spring centered, 3 position, 4 way directional control valve, convention has it that. a. Energizing Sol A will retract the cylinder b. De-energizing both Solenoids will retract the cylinder c. Energizing Solenoid B will retract the cylinder d. Centering springs will always retract the cylinder 5. With both solenoids de-energized, which internal component of the DCV returns the spool to its center condition a. The lands on the spool b. The undercut area of the spool c. The armature of the solenoid valve d. The centering springs 6. With both solenoids de-energized, what determined the pressure indicated on the system pressure gauge a. Pumps delivery (GPM) b. The relief valve c. The size of the ports on the DCV d. The resistance created by the hydraulic circuit 7. You are asked to troubleshoot a problem in the hydraulic circuit. The electrician states that the DCV will not shift to retract the cylinder and ask you to determine if problem is electrical or mechanical. What simple procedure will identify if the valve has an electrical or internal mechanical problem. a. Observe the vacuum reading indicated on the vacuum gauge b. Observe the pressure on the system pressure gauge c. De-energize both solenoids and try to move the cylinder using the manual override push pin d. Disconnect the hoses from the cylinder and manual extend and retract the cylinder 8. You identified in question 8 that the problem is electrical because the valve shifted when the manual over ride push pin were depressed. What electrical problem could have occurred to the valve? a. Both solenoids were energized at the same time b. The retract solenoid (B) has failed c. The electrician was energizing the wrong DCV d. All of the above Centennial College: Paul Bligdon Page 9
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help
Industrial Hydraulics for Colleges Industrial Hydraulics for Colleges Intro Intro 9. The engineer identifies that the hydraulic circuit using the all port blocked DCV creates a lot of heat and waste HP when the valve is in the Center Condition. What change would you recommend to the valve? a. Replace the valve spool with a tandem center spool b. Replace the valve spool with an open center spool c. Replace the valve spool with a float center spool d. Any of the above spools 10. The maximum flow rate (GPM) through a DCV is determined by: a. The size of the inlet and outlet hoses b. The port size of the valve and the spool undercut diameter c. The GPM supplied to the valve by the pump d. All of the above 11. What are the three functions of the balancing grooves machined on the lands of a hydraulic spool? a. b. c. 12. Why are all 33 different center condition valves spools interchangeable within a common valve body? a. The undercut diameters are the same b. The land diameters are the same c. Their maximum flow rates are the same d. All of the above 13. Maintenance is reporting that the Air Gap solenoids are failing frequently on the shop floor. What component change or system adjustment would you recommend? a. Reduce the system operating pressure b. Increase the size of the reservoir to dissipate more heat from the fluid c. Install a heat exchanger (cooler) d. Replace air gap solenoids with wet pin armature solenoids 14. Draw the ANSI symbol for a 3 position, 4 way, manually operated, spring centered. With open center condition Centennial College: Paul Bligdon Page 10
Industrial Hydraulics for Colleges Industrial Hydraulics for Colleges Intro Intro 15. Draw the hydraulic schematic of the lab circuit which used the solenoid operated directional control valve. ANSI Schematic Drawing Centennial College: Paul Bligdon Page 11