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1-Start Small 3-Way Presentation

1-Start Small 3-Way Presentation. 2-Mac manufactures valves that don’t stick. To show how this is accomplished we will look at the (3) parts of a solenoid valve. 3-The solenoid must have high shifting forces to shift through contamination. To do this we must have a short stroke solenoid.

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1-Start Small 3-Way Presentation

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  1. 1-Start Small 3-Way Presentation

  2. 2-Mac manufactures valves that don’t stick. To show how this is accomplished we will look at the (3) parts of a solenoid valve.

  3. 3-The solenoid must have high shifting forces to shift through contamination. To do this we must have a short stroke solenoid.

  4. 4-The return spring also must have high shifting forces to return the valve when the solenoid is de-energized.

  5. 5-The valve body must have low friction, wipe away contamination & have a balanced design to maintain our high shifting forces.

  6. 6-We can use a bar graph to demonstrate shifting forces. The valve is shifting because the forces are greater than the resistance.

  7. 7- In operation, if contamination is allowed to build, the resistance becomes greather than the shifting forces and the valves sticks.

  8. 8- The answer, is to increase the margin of shifting force in the solenoid, to overcome the resistance due to contamination.

  9. 9- And, to increase the margin of shifting force on the spring side. With higher margins the valve shifts.

  10. 10- A valve can have high shifting forces, but with high friction the margins are still low. Packed Spool Design!!

  11. 11- and with contamination the valve will stick.

  12. 12- A valve can have high shifting forces with low friction, and appear to have high margins. Lapped Spool Design !!

  13. 13- But, if contamination is not wiped away, we loose our margins and the valve will stick.

  14. 14- Mac maintains high margins with a balanced design,

  15. 15- low friction and

  16. 17- Lets take a close look at the valve solenoid assembly.

  17. 18- When we energize the solenoid the valve shifts.

  18. 19- With a long stroke solenoid our shifting forces are low. The force curve shows this relationship.

  19. 20- With Mac’s short stroke solenoid, our shifting forces are HIGH. Like holding two magnets close together.

  20. 21- Mac test each solenoid valve, to insure their high shifting forces.

  21. 22- In the test each valve must shift @80% of it’s rated voltage. This ensures the solenoid forces and 19.2 @24V 96@120V

  22. 23- the friction in the body meet the Mac guidelines. With high friction the valve would fail the 80% test.

  23. 24- A new valve @ 24volts would shift, but doesn’t have the margins to shift through contamination.

  24. 25- If contamination is not wiped away, we loose our margins and the valve will stick.

  25. 26- All Mac valves are shipped with high shifting forces and low resistance.

  26. 27- We have seen that a short stroke gives us a high force solenoid to shift the valve. We also need a strong spring to return the valve.

  27. 28- Solenoid & spring forces are related. With a long stroke solenoid our shifting forces are low. Therefore we must use a weak spring.

  28. 29- With a short stroke solenoid our shifting forces are high. Therefore we can use a strong “beefy” spring.

  29. 30- Mac also test each return spring, to ensure high return forces.

  30. 31- Each return spring must overcome a voltage to pass the test. This voltage on a 24 volt valve is 3 volts.

  31. 32 • CLICK BUTTON AGAIN

  32. 33- If drop-out is below 3 volts the spring is too weak to use. It would operate a new valve, but would stick with contamination.

  33. 34- All Mac valves are shipped with high shifting forces and low resistance.

  34. 35 • CLICK BUTTON AGAIN

  35. 36- We’ve seen that a short stroke=high shifting forces. Mac minimizes resistance in the valve body, by wiping contaminates, low friction & a balanced design.

  36. 37- To perform our tests in real life, we use a force tester. The tester is used to measure valve performance.

  37. 38- The tester has the following components.

  38. 40- Pressure is represented by the top trace, the on/off electrical trace is on the bottom. Each vertical grid is 20 psi, each horizontal grid is 2ms.

  39. 40- Let’s look at a complete valve cycle.

  40. 41- At point “A” the coil is energized.

  41. 42- From points “A to B” shows the energized response time.

  42. 43- From points “B to C”, we show the fill time, for the valve to reach line pressure.

  43. 44- At point “D”, the coil is de-energized.

  44. 45- From points “D to E”, shows the de-energized response time.

  45. 46- From points “E to F”, we show the exhaust time, to atmospheric pressure.

  46. 47- CLICK

  47. 48- Lets show how our TLD setup, is a valve force tester. Here we show 4ms response time at 24 volts.

  48. 49- At 13 volts our response time is 14ms.

  49. 50- At 36 volts our response time is 2ms. We can see how the response times have changed as we change the valve forces.

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