Procedure to Rework the Return Lines for the Margin Relief Valve{5057, 5069} Caterpillar

Introduction

This Special Instruction contains the required information in order to rework the return lines for the margin relief valve. These changes reduce the pressure surges in the return lines that result in failure of the hydraulic cooler.

Note: This procedure can be performed on Excavators that have been updated by the Product Improvement Program, SEBE7031, "The Margin Relief Valves Need To Be Relocated To The Implement Control Valve On Certain 5130 Excavator".

Reference: See Service Magazine 2 July, "Welding On Fuel and Hydraulic Tanks".

Reference: See Operation and Maintenance Manual, SEBU6551.

Read the entire special instruction. Understand the information before you perform any of the procedures. Understand the information before you order any of the parts.

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Personal injury or death can result from an explosion. Applying heat to a tank which has held flammable liquids, even when empty, can result in residual flammable liquid or vapor igniting with explosive force. Do Not weld or flame cut on any tank that has held flammable liquid without taking the proper precautions. Such as; filling the tank with either carbon dioxide or water. Read the article in the Service Magazine July 2,, "Welding On Fuel And Hydraulic Tanks".

Weld Specifications and Parameters

Note: Personal breathing protection should be worn by the welders. Personal breathing protection will prevent fumes from entering the lungs of the person that is welding. Use a 1U-8088 Type H Respirator for respiratory protection.

All of the welders must be qualified in Shielded Metal Arc Welding (SMAW). All of the welders must be qualified in the Flux Cored Arc Welding (FCAW) for groove welding or for fillet welding in the vertical position. Refer to the American National Standards Institute (ANSI)/American Welding Society (AWS) D1.1. Prior to welding, the process must have been used by the welders during the last six months. Welding qualifications must be documented and welding qualifications must be current.

The surrounding area must be a minimum temperature of 21 °C (70 °F) before welding and during welding.

The proper electrode for Shielded Metal Arc Welding (SMAW) is E7018 American National Standards Institute (ANSI)/American Welding Society (AWS) A5.1. The finished weld will have the following minimum mechanical properties:

• 500 MPa (72,519 psi) Tensile Strength

• 420 MPa (60,916 psi) Yield Strength

• 22 percent elongation in 50 mm (2 inch)

• 27 N·m (20 lb ft) at -29 °C (-20 °F) Impact Toughness

The E7018 electrodes must be stored in an electrode oven at 121 °C (250 °F). Scrap the E7018 electrodes or recondition the E7018 electrodes if the E7018 electrodes get damp. Recondition the E7018 electrodes to the manufacturer's specifications. The following table is the electrode's current settings in relation to the electrode's diameters:

Set the polarity to direct electrode positive (reverse polarity). Use the direct current. Remove the slag after every pass. The width of the weld should not exceed two times the electrode diameter.

Use the Flux Cored Arc Welding (FCAW) with E71T-1 (ANSI/A5.20) welding electrode and the manufacturer's shielding gases that are specified for inside welding. The weld that is deposited by three Flux Cored Arc Welding (FCAW) electrodes will have the following minimum mechanical properties:

• 500 MPa (72519 psi) Tensile Strength

• 420 MPa (60916 psi) Yield Strength

• 27 N·m (20 lb ft) Notch Thickness at -18 °C (-0 °F)

Note: The slag system of the E71T-1 (ANSI/A5.20) welding electrode has fast freezing characteristics. There is a chance of trapping gases that are evolving in the weld melt. The weld pass volume should be controlled with caution.

Note: Use the manufacturer's recommended welding electrode parameter.

Note: Use an ultrasound to test the weld quality in the area that was welded.

Parts

The following parts need to be purchased in order to perform the work.

Make the fabricated components before going to the job site. In order to produce the fabricated parts, details are found at the end of the special instruction.

Procedure to Rework the Return Lines

1. Remove the oil from the hydraulic tank and save the oil. Collect any fluid from an open line or from an open port into a suitable container. Protect all openings from contamination.

2. Remove the ladder and the grates in order to provide complete access to the lines groups in the swing frame.

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Illustration 1	g00809150

3. Remove 152-6611 Tube As (A) from 152-6613 Manifold Block (B) and 152-2119 Relief Valve (C). Discard the tube, the seals, the bolts and the washers.

4. Remove 152-6612 Tube As (D) from 152-6614 Manifold Block (E) and 152-2119 Relief Valve (C). Discard the tube and the seals. Save four 6V-0397 Half Flanges (F), eight 8T-4183 Bolts and eight 8T-4223 Hard Washers (H) for later use.

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Illustration 2	g00809162

5. Install one O-ring seal (2) into cover (1). Install cover (1) into Manifold block (B) by using the following components that were saved in step 4:two half Flanges (F), four bolts (G) and four hard washers (H).

6. Install one O-ring (2) into cover (1). Install cover (1) onto manifold block (E) by using the following components that were saved in step 4: two half Flanges (F), four bolts (G) and four hard washers (H) .

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Illustration 3	g00809481
Left Swing Frame (AA) 395 mm (15.6 inch) (BB) 123 mm (4.8 inch)

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Illustration 4	g00809483
Left Swing Frame (CC) 201 mm (7.9 inch) (DD) 120 mm (4.7 inch)

7. Tack weld two blocks (3) on the inside wall of the rail of the left swing frame.

8. Finish weld (W1) to the inside of the left swing frame. Refer to Illustration 3 and 4 and refer to Table 3.
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   Table 3

   Weld Tolerances
   Weld	Description
   W1	6 mm (0.24 inch) fillet weld
   W2	5 mm (0.20 inch) fillet weld
   W3	3 mm (0.12 inch) fillet weld

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Illustration 5	g00830557
Left Swing Frame (EE) 49 mm (2 inch) (FF) 504 mm (20 inch)

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Illustration 6	g00830558
Top view of block (4) and of the swing frame (GG) 88 mm (3.5 inch) (HH) 135 mm (5.3 inch)

9. Tack weld one block (4) on the top left rail of the swing frame.

10. Finish weld (W2) on block (4) to the left rail of the swing frame. Refer to Illustration 6 and refer to Table 4.
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    Table 4

    Weld Tolerances
    Weld	Description
    W2	5 mm (0.2 inch) fillet weld

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Illustration 7	g00831833
Hydraulic Tank (JJ) 1523 mm (60.00 inch) (KK) 216 mm (8.5 inch)

11. Prepare the hydraulic tank for flame cutting and for welding procedures. Remove the cover, filters, baffles, etc. Completely remove the oil and clean the tank.

12. Mark the position for block (5) on the hydraulic tank. Cut the correct sized hole in the hydraulic tank. The hole should measure 74 mm (2.9 inch) by 114 mm (4.5 inch). The edge of the hole and of the tank should be finished.

13. Tack weld block (5) to the tank wall.

14. Finish weld (W3) on block (5) to the tank wall. Refer to Illustration 7 and refer to Table 5.

    Note: The weld must not leak.

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    Table 5

    Weld Tolerances
    Weld	Description
    W3	5 mm (0.2 inch) fillet weld

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Illustration 8	g00831834
Hydraulic Tank (LL) 125 mm (4.9 inch) (MM) 275 mm (10.8 inch)

15. Locate 106-4751 Cover As (M) for the hydraulic tank. Cut a 38 mm (1.5 inch) hole (N) in the cover. The edge of the hole and of the tank should be finished.

16. Tack weld one fitting (6) to the top of the cover.

17. Finish weld (W4) on fitting (6) to the top of the cover. Refer to Illustration 8 and refer to Table 6.

    Note: The weld must not leak.

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    Table 6

    Weld Tolerances
    Weld	Description
    W4	5 mm (0.2 inch) fillet weld

18. Clean the hydraulic tank and reassemble the hydraulic tank. Use two seals (7) with the baffle assembly and one gasket (8) under the tank cover.

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Illustration 9	g00831835
(NN) 192 ± 5 mm (7.6 ± 0.2 inch) (PP) 769 ± 5 mm (30.0 ± 0.2 inch) (RR) 750 ± 5 mm (30.0 ± 0.2 inch)

19. Locate two bosses (9) on plate (P) of enclosure (R). Tack weld bosses (9) to the plate.

20. Finish weld (W5) on the bosses (9) to plate (P) of the enclosure. Refer to Illustration 9 and refer to Table 7.
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    Table 7

    Weld Tolerances
    Weld	Description
    W5	3 mm (0.12 inch) fillet weld

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Illustration 10	g00831838
(SS) 800 mm (31.5 inch) (TT) 68 mm (2.7 inch) (UU) 410 mm (16.1 inch)

21. Locate two bosses (9) on plate (T) of fuel tank (U). Tack weld bosses (9) to the plate.

22. Finish weld (W6) on the bosses to plate (T) of the fuel tank. Refer to Illustration 10 and refer to Table 8.
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    Table 8

    Weld Tolerances
    Weld	Description
    W6	3 mm (0.12 inch) fillet weld

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Illustration 11	g00831839
(VV) 538 mm (21.2 inch) (WW) 94 mm (3.7 inch) (XX) 81 mm (3.2 inch)

23. Tack weld two bosses (9) on the top flange of the catwalk.

24. Finish weld (W7) on the bosses (9) to the top flange of the catwalk. Refer to Illustration 11 and refer to Table 9.
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    Table 9

    Weld Tolerances
    Weld	Description
    W7	3 mm (0.12 inch) fillet weld

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Illustration 12	g00831840
Catwalk (YY) 236 ± 2 mm (9.3 ± 0.08 inch)

25. Locate two blocks (10) and two blocks (11). The blocks should be positioned in order to form the block assembly (V). Tack weld blocks (10) and blocks (11) together.

26. Finish weld (W8) the blocks together. Refer to Illustration 12 and refer to Table 10.
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    Table 10

    Weld Tolerances
    Weld	Description
    W8	3 mm (0.12 inch) fillet weld

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Illustration 13	g00831841
Catwalk (ZZ) 1624 ± 2 mm (63.9 ± 0.08 inch)

27. Locate block assembly (V) that was fabricated in Step 25. Locate the assembly on the underside of 194-2990 Support Assembly (W). Tack weld the assembly to the support.

28. Finish weld (W9) on block assembly (V) to the underside of 194-2990 Support Assembly . Refer to Illustration 13 and refer to Table 11.
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    Table 11

    Weld Tolerances
    Weld	Description
    W9	3 mm (0.12 inch) fillet weld

29. Clean all of the area that was welded. Paint the area that was welded. This prevents rust from forming on these areas.

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Illustration 14	g00830559

30. Locate the following components into the correct port:one reservoir (12), one elbow (13), O-ring seal (14) and one connector (15). Install the fittings and the seals into the correct ports of the reservoir.

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Illustration 15	g00830560

31. Install the following components:two plates (15), four bolts (16) and four washers (17). Install reservoir (12) to the block assembly (V) that is welded to the underside of 194-2990 Catwalk (W). Orient the elbow toward the rear of the machine. Reference Illustration 10 and 15.

32. Install the following components: one hose (19), one seal (20), two flanges (21), four bolts (22), four washers (23) and one seal (2). Install the hose (19) to the reservoir (12) and 152-2119 Relief Valve (C) .

33. Install the following components: one clamps (23), two spacers (24), one lock (25), two bolts (26) and two washers (22). Fasten the hose to block (4). Block (4) was welded to the top rail of the swing frame in Step 9.

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Illustration 16	g00832297

34. Locate one elbow (13) and one seal (28). Install the elbow and the seal to the fitting (6) in the hydraulic tank cover.

35. Install two seals (30) into hose (29). Install one hose (29) between the reservoir and the hydraulic tank. The hose will attach to six 9R-2613 Bosses on the following parts:catwalk, fuel tank and enclosure.

36. Use the following components to install hose (29) :six clips (31), six clips (32), six grommets (33), six washers (34) and six bolts (35)

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Illustration 17	g00832298

37. Locate the following components:one tube (36), four clips (37), four bolts (38) and four washers (22). Leave the bolts loose. Position the tube (36) in the swing frame and fasten the tube to the blocks (3). Secure tube (36) with the following items: four clips (37), four bolts (38) and four washers (22). Leave the bolts loose.

38. Install hose (39) with the straight end to the hydraulic tank. Secure hose (39) with the following components:four flanges (40), two seals (41), eight bolts (21) and eight washers (22) .

39. Install hose (42) with the straight end to the tube. Secure hose (42) with the following components:one seal (41), two flanges (40), four bolts (21) and four washers (22) .

40. Secure hose (18) with the following components:one seal (2), two flanges (20), four bolts (21) and four washers (22). Install the hose to the margin relief valve (C) .

41. Tighten the bolts that were left loose in Step 37.

42. Reinstall the floor grates to the swing frame. Install any other hardware that was removed during these procedures.

43. Refill the hydraulic tank. Refer to the Operation and Maintenance Manual, "Refill Capacities" for the appropriate oil and the correct amount of oil.

Fabricated Parts

Fabricate the following parts.

Fabrication of 190-1263 Block

Fabricate 190-1263 Block from mild steel.

Illustration 18	g00812477

Fabrication of 207-8551 Block

Fabricate 207-8551 Block from mild steel.

Illustration 19	g00832485

Fabrication of 202-6585 Block

Fabricate 202-6585 Block from high strength structural steel with a minimum yield of 207 MPa (30000 psi).

Illustration 20	g00812479