Testing Hydraulic Cylinders Using the 188-3926 Caterpillar Cylinder Tester and the 9U-6803 Caterpillar Cylinder Tester {0784, 7562} Caterpillar

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Introduction

© 2018 Caterpillar All Rights Reserved. This guideline is for the use of Cat Dealers only. Unauthorized use of this document or the proprietary processes therein without permission may be violation of intellectual property law. Information contained in this document is considered Caterpillar: Confidential Yellow.

This Reuse and Salvage guideline enables dealers and dealer customers to benefit from cost reductions made possible through an established parts reusability and salvage program Every effort has been made to provide the most current information known to Caterpillar Since the company makes ongoing product changes and product improvements, this guideline must be used with the latest technical information. Using the latest technical information available from Caterpillar ensures that such changes and improvements are incorporated where applicable.

For questions or additional information concerning this guideline, submit a feedback form in the Service Information System web site. To address an urgent need, use the following to forward your request to Caterpillar Repair Process Engineering:

• Cat Dealer Technical Communicator

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Canceled Part Numbers and Replaced Part Numbers

This document may not include canceled part numbers and replaced part numbers. Use NPR on SIS for information about canceled part numbers and replaced part numbers. NPR will provide the current part numbers for replaced parts.

Summary

Illustration 1	g01042701
Cylinder Tester

This guideline will enable dealers to test double acting cylinders and extension cylinders. The 188-3926 Caterpillar Cylinder Tester or 9U-6803 Caterpillar Cylinder Tester is used to perform the tests. The function of the cylinder tester is to conduct a leakage test of piston and rod seals in resealed hydraulic cylinders.

The test of whether piston and rod seals are resealed is determined in two (2) ways:

1. By watching the rod, piston drift, and external leaks at the rod. The seals will leak and cause the rod to drift if the wrong piston seals have been installed. Also, check to see if the seals have been "cut" during assembly. Damaged seals will also cause drifting or leaking.

2. By watching the rod, cap (and head) end, and gauge readings. If the pressures hold, piston and rod seals are resealed, the test was effective. If the pressures drop and equalize, a leakage path exists either through the seal or past a scratch in the cylinder wall.

The cylinder tester also functions by cycling the cylinder through the ROD EXTEND and ROD RETRACT strokes prior to testing. Refer to Tool Operating Manual, NEHS0595, "Tool Operating Manual for 188-3926 Cylinder Tester" before performing this procedure.

Note: Testing the cylinder at the operating pressure for the specific machine application is not required. Testing the cylinder at the pressure given in this procedure will properly verify the cylinder rebuild.

Important Safety Information

Illustration 2	g02139237

Most accidents that involve product operation, maintenance, and repair are caused by failure to observe basic safety rules or precautions. An accident can often be avoided by recognizing potentially hazardous situations before an accident occurs. A person must be alert to potential hazards. This person should also have the necessary training, skills, and tools to perform these functions properly. Safety precautions and warnings are provided in this instruction and on the product. If these hazard warnings are not heeded, bodily injury or death could occur to you or to other persons. Caterpillar cannot anticipate every possible circumstance that might involve a potential hazard. Therefore, the warnings in this publication and the warnings that are on the product are not all inclusive. If a tool, a procedure, a work method, or operating technique that is not recommended by Caterpillar is used, ensure that the procedure is safe for you and for other people to use. Ensure that the product will not be damaged or be made unsafe by the operation, lubrication, maintenance, or the repair procedures that are used.

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Improper operation, lubrication, maintenance or repair of this product can be dangerous and could result in injury or death. Do not operate or perform any lubrication, maintenance or repair on this product, until you have read and understood the operation, lubrication, maintenance and repair information.

Safety precautions and warnings are provided in this manual and on the product. If these hazard warnings are not heeded, bodily injury or death could occur to you or to other persons.

The hazards are identified by the safety alert symbol which is followed by a signal word such as danger, warning, or caution. The "WARNING" safety alert symbol is shown below.

Illustration 3	g00008666

This safety alert symbol means:

Pay attention!

Become alert!

Your safety is involved.

The message that appears under the safety alert symbol explains the hazard.

Operations that may cause product damage are identified by "NOTICE" labels on the product and in this publication.

Caterpillar cannot anticipate every possible circumstance that might involve a potential hazard. The safety information in this document and the safety information on the machine are not all inclusive. Determine that the tools, procedures, work methods, and operating techniques are safe. Determine that the operation, lubrication, maintenance, and repair procedures will not damage the machine. Also, determine that the operation, lubrication, maintenance, and repair procedures will not make the machine unsafe.

The information, the specifications, and the illustrations that exist in this guideline are based on information which was available at the time of publication. The specifications, torques, pressures, measurements, adjustments, illustrations, and other items can change at any time. These changes can affect the service that is given to the product. Obtain the complete, most current information before you start any job. Caterpillar dealers can supply the most current information.

Safety

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Hot oil and hot components can cause personal injury. Do not allow hot oil or hot components to contact skin.

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Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury, perform the procedure that follows before testing and adjusting the steering system.

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Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the attachments have been lowered, oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.

References

Tooling and Equipment

Testing Double Acting Cylinders

The following pressure test procedure detects leaks in double acting hydraulic cylinders. To test the piston and rod seals, add pressure to the oil cavity and block the release of oil from the cap end.

Illustration 4	g02597556
(1) Motor (2) Rod end (3) Cap (head) end (4) Test pressure adjustment (5) Load sensing, pressure compensated hydraulic pump (6) Directional control lever (7) Mode selector lever (8) Air selector valve (9) Start/stop switch (10) Air pressure supply line (11) Supply line to rod end (12) Supply line to cap (head) end (13) Purge line (14) TANK Line (15) Orifice (A) Rod end pressure gauge (B) Cap (head) end pressure gauge (C) System or test pressure gauge (D) Air pressure gauge

Procedure

1. Attach adapters for testing to the cylinder. The adapters should terminate in a 9U-7453 Nipple or 9U-7454 Nipple regardless of the connectors. The nipple mates with the 9U-7452 Quick Disconnects that are used on the test hoses. If the cylinder being tested has ports using SAE Code 61 or 62 bolt hole patterns, use either an XT-6ES flange adapter or an XT-3ES fitting adapter. Refer to Table 3.
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   Illustration 5	g03325142
   (2) Rod End Port

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   Illustration 6	g03325134
   (3) Cap (Head) End Port

2. Connect the cylinder test supply hoses to the 9U-7453 Nipple or 9U-7454 Nipple.

   Note: One cylinder hose for testing is marked “ROD”. Connect the rod end hose to the rod end port (2). The hose “CAP” connects to the cap (head) end port (3). The quick disconnects should be secure. The quick disconnects should not leak.

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   Illustration 7	g02604441
   (9) Start/stop switch

3. Start the hydraulic pump (5) by pushing START on the start/stop switch (9). Refer to Illustrations 4 and 7.
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   Illustration 8	g02615400
   (4) Test pressure adjustment (6) Directional Control Lever (7) Mode Selector Lever

4. The mode selector lever (7) allows the user to select between the CYLINDER CYCLE position and the CYLINDER TEST position. Move the mode selector lever (7) to the CYLINDER CYCLE position. Refer to Illustration 8.

5. The directional control lever (6) is used to control the state or position of the cylinder. Place the directional control lever (6) in the ROD RETRACT position, which is shown in Illustration 8. This setting will supply oil to the rod end of the cylinder. If the hoses have been connected correctly, the rod will retract. If the rod extends, the hoses must be switched. Relieve pressure before disconnecting the test hoses. Refer to Steps 14 and 15 to relieve system pressure.
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   Personal injury can result from removing hoses or fittings in a pressure system. Failure to relieve pressure can cause personal injury. Do not remove or disconnect hoses or fittings until all pressure in the air system has been relieved.

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   Illustration 9	g02616845
   (6) Directional Control Lever (7) Mode Selector Lever

6. Place the directional control lever (6) in the position ROD EXTEND. This setting will supply oil to the cap end of the cylinder. If the hoses have been connected correctly, the rod will extend. Refer to Illustration 9.

7. Fully extend and retract the rod 4 to 5 times. This action will expel any trapped air from the cylinder. As the cylinder is cycled, observe the rod and cap pressure gauges. This step is done to determine whether the piston and seals travel through any tight spots. With a constant flow of oil into the cylinder, there should be no significant change in pressure.
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   Illustration 10	g03325131

8. Extend the rod or retract the rod to center the piston in the cylinder. Refer to Illustration 10.

   Note: On cylinders with pistons that have built-in relief valves, the piston must be centered. Otherwise, test pressure will not build in the cylinder.

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   Illustration 11	g02616803
   (4) Test Pressure Adjustment (6) Directional Control Lever (7) Mode Selector Lever

9. Move the directional control lever (6) to the hold or CENTER CYLINDER TEST position. Move the mode selector lever (7) to the CYLINDER TEST position. Refer to Illustration 11.
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   Illustration 12	g02604336
   (4) Pressure Test Adjustment

10. Rotate the "TEST PRESSURE" adjustment (4) clockwise to increase the system pressure. The adjustment controls a variable pressure reducing valve to change the value of the pressure signal to the hydraulic pump. The test pressure for the cylinder is 20,680 kPa (3000 psi). When the test pressure is reached, turn the "TEST PRESSURE" adjustment counterclockwise to reduce the system pressure. Valves in the hydraulic circuit will maintain the test pressure on the cylinder. Observe gauges on the cylinder tester to see if leakage is occurring. Refer to Illustration 12.
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    NOTICE
    Do not exceed the test pressure. Damage will occur to the seals if the pressure exceeds the test pressure amount.

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    Illustration 13	g02604497
    (B) Cap (head) end pressure gauge (C) System or test pressure gauge (A) Rod end pressure gauge

11. Observe the ROD PRESSURE (A) and CAP PRESSURE (B) gauges for 30 seconds. The gauge readings should not drop. The gauge readings should also not be the same because of the difference in areas between the "rod" and "cap" sides of the piston. If the cylinder has been properly rebuilt and if there is no internal or external leakage, there should be no change in the gauge readings. Refer to Illustration 13.

12. Visually inspect the rod seals for oil leakage. If leakage occurs, perform Steps 14 through 20. Then, disassemble the damaged rod seal and replace the damaged rod seal.

13. Check for rod movement for 1 minute. Mount a dial indicator on the cylinder to measure the drift. A less precise method is the measuring of the head to the “grease pencil” marks on the rod. If the cylinder does not drift more than the allowable drift rate from Table 4, the test is complete. If the drift exceeds the Allowable Drift Rate from Table 4, perform Steps 14 through 20. Then, disassemble the cylinder and determine the cause of the leak. If a leak has been detected, observing the gauges on the Rod end and the Cap end will help determine the cause of failure.

    1. A path for leakage exists through a damaged piston seal or past a scratch in the cylinder wall if the pressures are equal.

    2. If both pressures drop, the rod seal may be damaged.

       Note: The cylinder might contain trapped air if the rod moves immediately after the applied test pressure. Repeat the procedure to purge the cylinder of air. The procedure will be more effective if each cylinder end is elevated and the rod is cycled.

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       Table 4

       Allowable Drift Rate (per minute)
       Description	mm (in)
       Current style square or rectangular cross section piston seals that have round cross section rings or oval cross section rings	3.0 mm (0.12 inch)
       Pistons with square ring packings	25 mm (0.98 inch)
       Pistons with U-cup piston seals	25 mm (0.98 inch)
       Pistons with chevron packing	25 mm (0.98 inch)

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    Illustration 14	g02616845
    (6) Directional Control Lever (7) Mode Selector Lever

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    Illustration 15	g02607856
    (9) Start/Stop Switch

14. Move lever (7) to the CYLINDER CYCLE position. Move lever (6) to the ROD EXTEND position and fully extend the rod. Refer to illustration 14. The hydraulic pump is turned off by pushing the start/stop switch (9) for STOP. Refer to Illustration 15.

    Note: The following steps are used to drain the oil in the cylinder.

15. Move lever (6) to ROD EXTEND and ROD RETRACT positions several times. This movement will relieve the pressure in the rod and the cap. Disconnect both oil supply hoses. Refer to Illustration 14.
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    Illustration 16	g03358069
    Rod Extended and Air Selector Valve in CLOSED Postion (1) Motor (2) Rod end (3) Cap (head) end (4) Test pressure adjustment (5) Load sensing, pressure compensated hydraulic pump (6) Directional control lever (7) Mode selector lever (8) Air selector Valve (9) Start/stop switch (10) Air pressure supply line (11) Supply line to rod end (12) Supply line to cap (head) end (13) Purge line (14) Tank Line (A) Rod end pressure gauge (B) Cap (head) end pressure gauge (C) System or test pressure gauge (D) Air pressure gauge

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    Illustration 17	g02608036
    Air Selector Valve Closed (2) Rod End (8) Air Selector Valve ( 9U-7318 Ball Valve) (10) Air Hose From Air Supply (14) TANK Line (D) Air Pressure Gauge

    Note: Illustration 16 shows the rod fully retracted. Fully extend the rod before hooking up the tooling.

16. Move lever on the air selector valve (8) to the CLOSED position to block air pressure to the cylinder. Connect the air selector valve (8) to the rod end port (2). Refer to Illustration 17.

    Note: The air pressure gauge (D) must read zero before attaching the air hose. Refer to Illustration 17.

17. Connect the hose labeled “TANK” line (14) to the end port (3) on the cap (head) end. Rotate the cylinder so the port on the cap (head) end faces downward to help drain oil. Refer to Illustrations 16 and 17.

18. Move the lever on the air selector valve (8) to the OPEN position. To direct air into the rod end of the cylinder to RETRACT the cylinder. Oil in the cap (head) end of the cylinder will return to the tank. Refer to Illustration 17.

19. Rotate the lever on the air selector valve (8) to the CLOSED position. This movement will block the air pressure supply and vent the cylinder rod end pressure. When the pressure gauge (D) indicates “0” (zero), the tooling may be removed. Refer to Illustration 17.

20. Disconnect all adapters and test equipment from the cylinder. Cover all ports with blocking covers, tape, or similar material.

Testing Two and Three-Stage Extension Cylinders and Hoist Cylinders

The following pressure test procedure detects leaks in extension cylinders and hoist cylinders. Adding pressure to the rod end while blocking oil from the cap end tests the piston and rod seals.

Illustration 18	g02609696
(1) Motor (2) Retract end (3) Extend end (4) Test pressure adjustment (5) Load sensing, pressure compensated hydraulic pump (6) Directional control lever (7) Mode selector lever (8) Air selector valve (9) Start/stop switch (10) Air pressure supply line (11) Supply line to rod (retract) end (12) Supply line to cap (extend) end (13) Purge line (14) TANK Line (15) Orifice (A) Rod end (retract) pressure gauge (B) Cap (head) (extend) end pressure gauge (C) System or test pressure gauge (D) Air pressure gauge

Procedure

1. Attach adapters for testing to the cylinder. The adapters should terminate in a 9U-7453 Nipple or 9U-7454 Nipple regardless of the connectors. The nipple mates with the 9U-7452 Quick Disconnects that are used on the test hoses. If the cylinder being tested has ports using SAE Code 61 or 62 bolt hole patterns, use either an XT-6ES flange adapter or an XT-3ES fitting adapter. Refer to Table 3.
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   Illustration 19	g03325122
   (2) Retract Port

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   Illustration 20	g03325130
   (3) Extend Port

2. Connect the cylinder test supply hoses to the 9U-7453 Nipple or 9U-7454 Nipple.

   Note: One cylinder hose for testing is marked “ROD”. Connect the rod end hose to the retract port. The hose marked “CAP” connects to the extend port. The quick disconnects should be secure. The quick disconnects should not leak.

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   Illustration 21	g02604441
   (9) Start/stop switch

3. Start the hydraulic pump (5) by pushing START on the start/stop switch (9). Refer to Illustration 21.
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   Illustration 22	g02616823
   (6) Directional Control Lever (7) Mode Selector Lever

4. The mode selector lever (7) allows the user to select between the CYLINDER CYCLE position and the CYLINDER TEST position. Move the mode selector lever (7) to the CYLINDER CYCLE position. Refer to Illustration 22.

5. The directional control lever (6) is used to control the state or position of the cylinder. Place the directional control lever (6) in the position ROD RETRACT, which is shown in Illustration 22. This setting will supply oil to the retract port of the cylinder. If the hoses have been connected correctly, the cylinder will retract. If the cylinder extends, the hoses must be switched. If the rod extends, the hoses must be switched. Relieve pressure before disconnecting the test hoses. Refer to Steps 14 and 15 to relieve system pressure.
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   Personal injury can result from removing hoses or fittings in a pressure system. Failure to relieve pressure can cause personal injury. Do not remove or disconnect hoses or fittings until all pressure in the air system has been relieved.

   Note: Continually monitor the cylinder tester tank level. A larger extension cylinder might require more oil for full extension. The oil reservoir for testing might not have enough oil.

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   Illustration 23	g02616845
   (6) Directional Control Lever (7) Mode Selector Lever

6. Place the directional control lever (6) in the position ROD EXTEND. This setting will supply oil to the extend end of the cylinder. If the hoses have been connected correctly, the cylinder will extend. Refer to Illustration 23.

7. Extend and retract the rod 4 to 5 times. This action will expel any trapped air from the cylinder. As the cylinder is cycled, observe the rod and cap pressure gauges. This step is to determine whether the piston and seals travel through any tight spots. With a constant flow of oil into the cylinder, there should be no significant change in pressure. A change in pressure may occur in areas with wear that has created looser fits.
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   Illustration 24	g03325118

8. Fully extend the cylinder. Retract the small cylinder stage halfway.
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   Illustration 25	g02616803
   (4) Test Pressure Adjustment (6) Directional Control Lever (7) Mode Selector Lever

9. Move the directional control lever (6) to the hold or CENTER CYLINDER TEST position. Move the mode selector lever (7) to the CYLINDER TEST position. Refer to Illustration 25.
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   Illustration 26	g02604336
   (4) Pressure Test Adjustment

10. Rotate the "TEST PRESSURE" adjustment (4) clockwise to increase the system pressure. The adjustment controls a variable pressure reducing valve to change the value of the pressure signal to the hydraulic pump. The test pressure for the cylinder is 20,680 kPa (3000 psi). When the test pressure is reached, turn the "TEST PRESSURE" adjustment counterclockwise to reduce the system pressure outside the cylinder. Valves in the hydraulic circuit will maintain the test pressure in the cylinder. Observe gauges on the cylinder tester to see if leakage is occurring. Refer to Illustration 26.
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    NOTICE
    Do not exceed the test pressure. Damage will occur to the seals if the pressure exceeds the test pressure amount.

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    Illustration 27	g02604497
    (B) Cap (head) end pressure gauge (C) System or test pressure gauge (A) Rod end pressure gauge

11. Observe the ROD PRESSURE (A) and CAP PRESSURE (B) gauges for 30 seconds. The gauge readings should not drop. The gauge readings should also not be the same because of the difference in areas between the "rod" and "cap" sides of the piston. If the cylinder has been properly rebuilt and if there is no internal or external leakage, the gauge readings should have no change. Refer to Illustration 27.

12. Visually inspect the rod seals for oil leakage. If leakage occurs, perform Steps 14 through 20. Then, disassemble the damaged rod seal and replace the damaged rod seal.

13. Check for rod movement for 1 minute. Mount a dial indicator on the cylinder to measure the drift. A less precise method is the measuring of the head to the “grease pencil” marks on the rod. If the cylinder does not drift more than the allowable drift rate from Table 5, the test is complete. If the drift exceeds the Allowable Drift Rate from Table 5, perform Steps 14 through 20. Then, disassemble the cylinder and determine the cause of the leak. If a leak has been detected, observing the gauges on the Rod End and the Cap End will help determine the cause of failure.

    1. A path for leakage exists through a damaged piston seal or past a scratch in the cylinder wall if the pressures are equal.

    2. If both pressures drop, the rod seal may be damaged.

       Note: The cylinder might contain trapped air if the rod moves immediately after the applied test pressure. Repeat the procedure to purge the cylinder of air. The procedure will be more effective if each cylinder end is elevated and the rod is cycled.

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       Table 5

       Allowable Drift Rate (per minute)
       Description	mm (in)
       Current style square or rectangular cross section piston seals that have round cross section rings or oval cross section rings	3.0 mm (0.12 inch)
       Pistons with square ring packings	25.0 mm (0.98 inch)
       Pistons with U-cup piston seals	25.0 mm (0.98 inch)
       Pistons with chevron packing	25.0 mm (0.98 inch)

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    Illustration 28	g02607856
    (9) Start/Stop Switch

14. Move the mode selector lever (7) to the CYLINDER CYCLE position. Move the directional control lever (6) to the ROD EXTEND position and fully extend the cylinder. Turn off the hydraulic pump by pushing the start/stop switch (9) for STOP. Refer to Illustrations 25 and 28.

    Note: The following steps are used to drain the oil in cylinders.

15. Move the directional control lever (6) to ROD EXTEND and ROD RETRACT positions several times. This movement will relieve the pressure in the rod and the cap. Disconnect both oil supply hoses. Refer to Illustration 25.
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    Illustration 29	g03358084
    Rod Extended and Air Selector Valve In CLOSED Position. (1) Motor (2) Retract end (3) Extend end (4) Test pressure adjustment (5) Load sensing, pressure compensated hydraulic pump (6) Directional control lever (7) Mode selector lever (8) Air selector valve (9) Start/stop switch (10) Air pressure supply line (11) Supply line to rod (retract) end (12) Supply line to cap (extend) end (13) Purge line (14) TANK Line (A) Rod end (retract) pressure gauge (B) Cap (head) (extend) end pressure gauge (C) System or test pressure gauge (D) Air pressure gauge

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    Illustration 30	g02604596
    Air Selector Valve Closed (2) Retract Port (8) Air Selector Valve (9U-7318 Ball Valve) (10) Air Hose From Air Supply (14) TANK Line (D) Air Pressure Gauge

    Note: Fully extend the rod before hooking up the tooling. Refer to Illustration 30.

16. Move lever on the air selector valve (8) to the CLOSED position to block air pressure to the cylinder. Connect the air selector valve (8) to the Retract port (2). Refer to Illustration 30.

    Note: The air pressure gauge (D) must read zero before attaching the air hose.

17. Connect the hose labeled “TANK” line (14) to the Extend port (3). Rotate the cylinder so the Extend port faces downward to help drain the oil. Refer to Illustrations 29 and 30.

18. Move the lever on the air selector valve (8) to the CLOSED position to direct air into the Retract port of the cylinder. The small stage of the cylinder collapses when the air is directed into the Retract port. The oil in the cylinder will return to the tank through the Extend port. Refer to Illustration 30.

    Note: Monitor the cylinder tester oil tank level. Remove oil from the tank so the cylinder collapses.

19. Rotate the lever on the air selector valve (8) to the CLOSED position. This movement will block the air pressure supply and vent the cylinder rod end pressure. When the pressure gauge (D) indicates “0” (zero), the tooling may be removed. Refer to Illustration 30.

20. Disconnect all adapters and test equipment from the cylinder. Cover all ports with blocking covers, tape, or similar material.

Four Stage Ejection Cylinders

The following pressure test procedure detects leaks in multi-stage extension cylinders. Add pressure to the Retract port while measuring the amount of oil leakage from the Extend port. This tests the piston seals and rod seals.

Cylinder Test Schematic

Illustration 31	g02615342
(1) Motor (2) Retract Port (3) Extend Port (4) Test pressure adjustment (5) Load sensing, pressure compensated hydraulic pump (6) Directional control lever (7) Mode selector lever (8) Air selector valve (9) Start/stop switch (10) Air pressure supply line (11) Supply line to retract end (12) Supply line to extend end (13) Purge line (14) TANK Line (15) Flow meter (16) Purge bolt (A) Rod end (retract) pressure gauge (B) Cap (head) (extend) end pressure gauge (C) System or test pressure gauge (D) Air pressure gauge

Procedure

1. Attach adapters for testing to the cylinder. The adapters should terminate in a 9U-7453 Nipple or 9U-7454 Nipple regardless of the connectors. The nipple mates with the 9U-7452 Quick Disconnects or 9U-7455 Quick Disconnects on the test hoses. If the cylinder being tested has ports using SAE Code 61 or 62 bolt hole patterns, use either an XT-6ES flange adapter or an XT-3ES fitting adapter. Put a 2 L (0.5 US gal) to 19 L (5 US gal) flow meter on the extension port to measure cylinder piston leakage. Refer to Table 3.
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   Personal injury can result from removing hoses or fittings in a pressure system. Failure to relieve pressure can cause personal injury. Do not remove or disconnect hoses or fittings until all pressure in the air system has been relieved.

2. Connect the supply hoses for the cylinder test to the 9U-7453 Nipple or 9U-7454 Nipples.

   Note: One test hose for the cylinder is marked “ROD” (11). Connect the rod end hose to the retract port (2). Connect the other hose marked “CAP” (12) to the extend port (3). Make sure that the quick disconnects are secure and that the quick disconnects do not leak. Refer to Illustration 31.

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   Illustration 32	g02617356
   (16) Purge Bolt

3. Remove the purge bolt (16) from the side of the cylinder before testing an ejector cylinder. This step will help to expel trapped air from the cylinder. Install a clear plastic line into the hole of the purge bolt (16). Place the other end of the line into a suitable container for collecting oil from the cylinder. Refer to Illustration 32.
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   Illustration 33	g02604441
   (9) Start/stop switch

4. Start the hydraulic pump (5) by pushing START on the start/stop switch (9).
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   Illustration 34	g02615400
   (6) Directional Control Lever (7) Mode Selector Lever

5. Ensure that the"Test Pressure" knob (4) is turned counterclockwise so that the system pressure is zero. Refer to Illustration 34.

6. The mode selector lever (7) allows the user to select between the CYLINDER CYCLE position and the CYLINDER TEST position. Move the mode selector lever (7) to the CYLINDER CYCLE position. Refer to Illustration 34.

7. The directional control lever (6) is used to control the state or position of the cylinder. Place the directional control lever (6) in theROD RETRACT position, which is shown in Illustration 34. This setting will supply oil to the rod end of the cylinder. If the hoses have been connected correctly, the rod will retract. If the rod extends, the hoses must be switched. Relieve pressure before disconnecting the test hoses. Refer to Steps 15 and 16 to relieve system pressure.
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   Personal injury can result from removing hoses or fittings in a pressure system. Failure to relieve pressure can cause personal injury. Do not remove or disconnect hoses or fittings until all pressure in the air system has been relieved.

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   Illustration 35	g02604336
   (4) Pressure Test Adjustment

8. Turn the "Test Pressure" knob (4) clockwise to increase pressure. When oil begins to flow out of the purge bolt (16) hole, move the directional control lever (6) to the center position. Refer to Illustrations 35 and to 34.

9. Reinstall the purge bolt (16). Refer to Illustration 32.

10. Move the directional control lever (6) back to ROD RETRACT. Fully retract the cylinder. Refer to Illustration 34.

    Note: Telescopic cylinders are only pressure tested in the full retract position. Other cylinders are stopped midway between retract and extend and then pressure tested.

11. Turn the "Test Pressure" knob (4) clockwise to increase the system pressure to the Test Pressure 20,680 kPa (3000 psi). Refer to Illustration 34.
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    NOTICE
    Do not exceed the test pressure. Damage will occur to the seals if the pressure exceeds the test pressure amount.

12. Visually inspect the rod seals for oil leakage. If leakage occurs, perform Steps 14 through 20. Then, disassemble the damaged rod seal and replace the damaged rod seal.

    Note: There will be evidence of oil around the wiper seals on each stage of a retracted cylinder under normal operation. An ejector cylinder might have hydraulic oil around the wiper seals and the cylinder would be classified as seeping. Table 6 can help determine if the cylinder seals are working properly.

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    Table 6

    Classification of Oil that is Evident from the Wiper Seals of the Ejector Cylinder
    Classification	Description
    Moist	Oil film does not result in forming droplets of oil.
    Seep	The oil film develops a visible droplet.
    Weep	Oil that reoccurs forms droplets that are seen along the length of the cylinder.
    Leak	Oil that reoccurs creates a visible stream of droplets of oil.

    Note: Leakage that is classified as “Moist” is normal. Leakage that is classified “Seep” is normal for a used cylinder. Repair may provide improvement but repair is not necessary. Leakage that is classified as “Weep” or “Leak” is not normal and repair is necessary.

13. Measure the discharge flow from the extend port. Refer to the specifications in Table 7 for the cylinder for the allowable leakage from the rod end to the head end.
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    Table 7

    Allowable Leakage for Ejector Cylinders
    177-2004	4 L/min (1.06 US GPM)
    191-5115	4 L/min (1.06 US GPM)

14. The cylinder must be disassembled and the leaking piston seal must be identified and replaced if more leakage is present than allowed in the specifications.
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    Illustration 36	g02607856
    (9) Start/Stop Switch

15. After pressure testing the cylinder and measuring the discharge flow, lower the test pressure to zero by turning the "Test Pressure" knob (4) counterclockwise. Refer to Illustration 35.

16. Push the start/stop switch (9) STOP to turn off the hydraulic pump. Refer to Illustration 36.

    Note: The following steps are used to drain the oil in the cylinders. When a telescopic cylinder is fully retracted, there is little oil remaining in the cylinder. The oil to be drained should be filtered before returning to the tank.

17. Move directional control lever (6) to ROD EXTEND and ROD RETRACT positions several times. This movement will relieve the pressure in the cylinder. Disconnect the oil supply hoses. Refer to Illustration 34.

18. Install a plug into the Retract port (2). Refer to Illustration 31.

19. Connect the hose labeled “TANK” line (14) to the Extend port (3). Rotate the cylinder so the Extend port faces downward to help drain the oil. Raise the cylinder, if needed, to more completely drain the oil. Refer to Illustration 31.

20. Remove the plug and the hose labeled “TANK” line (14). Refer to Illustration 31.

21. Install a plug into the Extend port (3). Refer to Illustration 31.

22. Connect the hose labeled “TANK” line (14) to the Retract port (2). Rotate the cylinder so the Retract port faces downward to help drain oil. Raise the cylinder, if needed, to more completely drain the oil. Refer to Illustration 31.

23. Disconnect all adapters and test equipment from the cylinder. Cover all ports with blocking covers, tape, or similar material.