Installation of Improved Walkways on 793C and 793C XQ Off-Highway Trucks{7254, 7255, 7256} Caterpillar

Introduction

This Special Instruction explains the installation of the improved walkways on the 793C and 793C XQ Off-Highway Trucks. Do not begin the installation until you have read the information that is contained in this instruction.

Safety

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Personal injury can result from flame cutting or welding on painted areas. The effect of gasses from burned paint is a hazard to the person doing the cutting or welding. Do not flame cut or weld on painted areas.

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Personal injury or death can result from fumes, gases and ultraviolet rays from the weld arc. Welding can cause fumes, burn skin and produce ultraviolet rays. Keep your head out of the fumes. Use ventilation, exhaust at the arc, or both, to keep fumes and gases from your breathing area. Wear eye, ear and body protection before working. Protect yourself and others; read and understand this warning. Fumes and gases can be dangerous to your health. Ultraviolet rays from the weld arc can injure eyes and burn skin. Electric shock can cause death. Read and understand the manufacturer's instructions and your employer's safety practices. Do not touch live electrical parts. See "American National Standard Z49.1, Safety in Welding and Cutting" published by the American Welding Society. American Welding Society 2501 N.W. 7th Street Miami, Florida 33125 See "OSHA Safety and Health Standards, 29 CFR 1910", available from U.S. Department of Labor. U.S. Department of Labor Washington, D.C. 20210

Work safely. 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 in order to perform these functions properly.

ReferenceRefer to the Special Instruction, REHS1841, "General Welding Procedures" when you perform any welding procedures during this instruction, as needed.

Needed Parts

The required parts for the field installation of the improved walkways are listed in Table 1.

Required Tooling

Specifications for Cables, Chains, and Lifting Devices

Use approved cables, chains, and lifting devices in order to lift components. Refer to the manufacturer's weight's in order to determine the application when you select the following items: cable, chain and lifting devices. When you lift a component, the lift angle is critical. Refer to the Illustration that follows in order to see the effect of the lift angle on the working load limit.

Note: The lifting devices that are shown in this publication are not AVSpare parts.

Illustration 1	g00629745
Lift angles for lifting slings. (A) The load capacity is 100% of the working load limit for the sling. (B) The load capacity is 86% of the working load limit for the sling. (C) The load capacity is 70% of the working load limit for the sling. (D) The load capacity is 50% of the working load limit for the sling.

Fabrication of the Required Parts

Fabricate all parts out of plain carbon steel.

Fabrication of the Required Blocks

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Illustration 2	g01404058

1. Fabricate two blocks (A) to the given dimensions.

   B ... 20 mm (0.8 inch)

   C ... 10 mm (0.4 inch)

   D ... 41 mm (1.61 inch)

   E ... 70 mm (2.8 inch)

   F ... 125 mm (5.0 inch)

   G ... 40 mm (1.60 inch)

   (H) Two 8.2 + 0.30 - 0.10 mm (0.323 + 0.012 - 0.004 inch) holes with 3/8-16-2B threads

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Illustration 3	g01404059

2. Fabricate eight blocks (J) to the given dimensions.

   K ... 10 mm (0.4 inch)

   L ... 10 mm (0.4 inch)

   M ... 26 mm (1.024 inch)

   N ... 64 mm (2.52 inch)

   P ... 101 mm (4.0 inch)

   R ... 38 mm (1.5 inch)

   (S) Two 8.2 + 0.30 - 0.10 mm (0.323 + 0.012 - 0.004 inch) holes with 3/8-16-2B threads

Fabrication of the Required Shims

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Illustration 4	g01404063

1. Fabricate shims (T) to the given dimensions.

   U ... 20 mm (0.8 inch)

   V ... 3 mm (0.12 inch)

   W ... 41 mm (1.61 inch)

   X ... 70 mm (2.8 inch)

   Y ... 125 mm (5.0 inch)

   Z ... 40 mm (1.60 inch)

   (BB) Two 11 + 0.30 - 0.10 mm (0.4331 + 0.012 - 0.004 inch) holes

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Illustration 5	g01404065

2. Fabricate shims (CC) to the given dimensions.

   DD ... 10 mm (0.4 inch)

   EE ... 3 mm (0.12 inch)

   FF ... 26 mm (1.024 inch)

   GG ... 64 mm (2.52 inch)

   HH ... 101 mm (4.0 inch)

   JJ ... 38 mm (1.5 inch)

   (KK) Two 11 + 0.30 - 0.10 mm (0.4331 + 0.012 - 0.004 inch) holes

Fabrication of the New Fender Brace

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Illustration 6	g01404066

1. Fabricate tube (LL) .

   MM ... 42.2 mm (1.66 inch)

   NN ... 350 mm (13.78 inch)

   PP ... 363 mm (14.30 inch)

   (RR) 3.56 mm (0.14 inch)

2. Weld a plug in the straight end of tube (LL) .

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Illustration 7	g01404068
Side view

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Illustration 8	g01404070
Rear view

3. Fabricate plate (SS) .

   TT ... 20 mm (0.79 inch)

   UU ... 15 mm (0.60 inch)

   VV ... 13.5 mm (0.53 inch)

   WW ... 13.5 mm (0.53 inch)

   XX ... 60 mm (2.36 inch)

   YY ... 10 mm (0.40 inch)

   ZZ ... 50 mm (1.97 inch)

   AB ... 2 X 5 mm (0.20 inch)

   AC ... 42.2 mm (1.66 inch)

   AD ... 13 mm (0.51 inch)

   AE ... 68.2 mm (2.685 inch)

   AF ... 125 mm (5.0 inch)

   AG ... 6 mm (0.24 inch)

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Illustration 9	g01404071
(W1) 3 mm (0.12 inch) Fillet weld

4. Weld plate (SS) onto tube (LL) .

Removal of the Existing Parts

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Illustration 10	g01391648

1. Remove nine bolts (A) and nine washers (B) in order to remove fender (C). Use a suitable lifting device in order to assist in lifting fender (C). Retain all parts.

   Note: Fender (C) weighs approximately 48 kg (106 lb).

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Illustration 11	g01391782

2. Remove three bolts (D), three washers (E), and three nuts (F) in order to remove mirror (G). Retain mirror (G) .

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Illustration 12	g01391794

3. Use a suitable lifting device in order to assist in lifting handrail (K) .

   Note: Handrail (K) weighs approximately 18 kg (40 lb).

4. Remove twelve bolts (H) and twelve washers (J) in order to remove handrail (K) .

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Illustration 13	g01391813

5. Remove twenty bolts (L) and twenty washers (M) in order to remove handrail (N). Use a suitable lifting device in order to assist in lifting handrail (N) .

   Note: Handrail (N) weighs approximately 53.5 kg (118 lb).

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Illustration 14	g01404072

6. Attach a suitable lifting device (P) to walkway (R) in order to lift walkway (R) .

   Note: Walkway (R) weighs approximately 135 kg (300 lb).

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Illustration 15	g01404073

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Illustration 16	g01404074

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Illustration 17	g01404075

7. Remove 36 bolts (S) and 36 washers (T) in order to remove walkway (R) .

8. Use lifting device (P) in order to remove walkway (R) from the truck.

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Illustration 18	g01404076

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Illustration 19	g01404077
Front left hand view

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Illustration 20	g01404078
Front side view

9. Attach a suitable lifting device to air cleaner (U) in order to lift air cleaner (U) .

   Note: Air cleaner (U) weighs approximately 204 kg (450 lb).

10. Loosen clamps (V) and clamp (W) in order to remove air cleaner (U) .

11. Remove four bolts (X) and four washers (Y). Retain all parts.

12. Remove four bolts (Z) and four washers (BB). Retain all parts.

13. Remove air cleaner (U) from the truck.

Modifications

Cab Modifications

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Illustration 21	g01393754
View of the left side of the cab

1. Use grinder (AA) in order to remove block (A) and block (B) from the bottom of the cab.

   Note: After you remove block (A) and block (B), grind the area until the area is smooth.

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Illustration 22	g01393758
View of the front of the cab

2. Use grinder (AA) in order to remove block (C) from the bottom of the cab.

   Note: After you remove block (C), grind the area until the area is smooth.

Modifications to the Air Cleaner

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Illustration 23	g01394765
Rear view of the air cleaner (D) 281 mm (11.063 inch) (E) 287 mm (11.30 inch)

1. Use the given measurements in order to mark the air cleaner.

   Note: The given measurements are the center of the notches that are needed.

2. Cut a slot of 25 mm (0.98 inch) by 25 mm (0.98 inch) in two places from the top rear of the air cleaner.

Modifications to the Fender

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Illustration 24	g01395154
(F) 520 mm (20.5 inch) (G) 507 mm (19.96 inch)

1. Mark measurement (F) and measurement (G) .

2. Scribe a line between mark (F) and mark (G) .

3. Cut along the scribed line in order to remove fender support (H) .

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Illustration 25	g01395187
(K) 14.5 mm (0.60 inch)

4. Enlarge slot (J) .

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Illustration 26	g01395198
(L) 703 mm (27.7 inch) (M) 75 mm (3.0 inch) (N) 64 mm (2.52 inch)

5. Mark measurement (L), measurement (M), and measurement (N) .

6. Scribe a line between mark (M) and mark (N) .

7. Cut fender (P) along the scribed line.

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Illustration 27	g01404079
(R) 15 mm (0.60 inch) (S) 15 mm (0.60 inch)

8. Cut radius (R) and radius (S) from fender (P) .

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Illustration 28	g01404080

9. Scribe a line from measurement (L) to mark (T) .

10. Cut fender (P) along the scribed line. Stop the cut once you reach radius (S) .

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Illustration 29	g01404081

11. Attach the new fender brace (U) that was fabricated in the ""Fabrication of the Required Fender Brace" " section. Use bolt (1), washer (2), washer (3), washer (4), and nut (5) in order to install fender brace (T) to fender (P) .

12. Position fender brace (U) firmly against fender (P) .

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Illustration 30	g01404082
(W1) 3 mm (0.12 inch) Double side fillet weld

13. Weld fender brace (U) to fender (P) .

Installation of the Improved Walkways

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Illustration 31	g01394133
Top view of walkway (1)

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Illustration 32	g01394134

1. Use sixteen bolts (9) and sixteen washers (5) in order to install blocks (3) to walkway (1). Block (3) was fabricated in Step 2 of the ""Fabrication of the Required Blocks" " section.

2. Use a suitable lifting device in order to position walkway (1) to the truck.

   Note: Walkway (1) weighs approximately 94 kg (207 lb).

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Illustration 33	g01394183

3. Install walkway (1) to the truck with ten bolts (4) and ten washers (5) .

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Illustration 34	g01394209

4. Install walkway (1) to the truck with ten washers (5) and ten bolts (6) .

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Illustration 35	g01394232
View of the bottom side of walkway (1)

5. Use two bolts (9) in order to hold block (3) against the bottom of the truck cab. Measure the gap between block (3) and walkway (1).

   Note: Use Table 5 in order to keep a record of the gap between block (3) and walkway (1). This information will be used to assist in installing the correct number of shims (7). Shims (7) were fabricated in Step 2 of the ""Fabrication of the Required Shims" " section.

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   Table 5

   Block	Measured Gap
   1
   2
   3
   4
   5
   6
   7
   8

6. Tack weld block (3) to the bottom side of the truck cab.

7. Repeat Step 5 through Step 6 for the seven remaining blocks (3) .

8. Use a suitable lifting device in order to lift walkway (1) .

   Note: Walkway (1) weighs approximately 94 kg (207 lb).

9. Remove sixteen bolts (9) and sixteen washers (5) that were installed in Step 1. Retain all hardware.

10. Remove ten bolts (4), ten bolts (6), and twenty washers (5) that were installed in Step 3 and Step 4. Retain all hardware.

11. Remove walkway (1) from the truck.

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Illustration 36	g01394356
(W1) 6 mm (0.24 inch) Double side fillet weld

12. Weld block (3) to the bottom side of the truck cab.

    Note: Ensure that you only weld along the long side of block (3) .

13. Repeat Step 12 for the seven remaining blocks (3) .

14. Use a suitable lifting device in order to position walkway (1) to the truck.

    Note: Walkway (1) weighs approximately 94 kg (207 lb).

15. Reinstall ten bolts (4), ten bolts (6), and twenty washers (5) that were removed in Step 10.

16. Install the correct number of shims (7) that was measured in Step 5.

17. Repeat Step 16 for the remaining seven blocks (3) .

18. Reinstall sixteen bolts (9) and sixteen washers (5) that were removed in Step 9.

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Illustration 37	g01394405
Top view of walkway (2)

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Illustration 38	g01394531

19. Use four bolts (9) and four washers (5) in order to install blocks (8) to walkway (2). Blocks (8) were fabricated in Step 1 of the ""Fabrication of the Required Blocks" " section.

    Note: Make sure that the orientation of block (8) is correct. Refer to Illustration 38.

20. Use a suitable lifting device in order to position walkway (2) to the truck.

    Note: Walkway (2) weighs approximately 42 kg (93 lb).

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Illustration 39	g01394536

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Illustration 40	g01394537

21. Install walkway (2) to the truck with sixteen bolts (10) and sixteen washers (11) .

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Illustration 41	g01394538

22. Secure walkway (1) to walkway (2) with three bolts (12), three nuts (13), and six washers (14) .

    Note: Ensure that both surfaces of the walkways are flush with each other in order to avoid trip hazards.

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Illustration 42	g01394602

23. Use two bolts (9) in order to hold block (8) against the bottom of the truck cab. Measure the gap between block (8) and walkway (2) .

    Note: Use Table 6 in order to keep a record of the gap between block (8) and walkway (2). This information will be used to assist in installing the correct number of shims (15). Shims (15) were fabricated in Step 1 of the ""Fabrication of the Required Shims" " section.

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    Table 6

    Block	Measured Gap
    1
    2

24. Tack weld block (8) to the bottom side of the truck cab.

25. Repeat Step 23 through Step 24 for the one remaining block (8) .

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Illustration 43	g01394575
(W2) 6 mm (0.24 inch) Double side fillet weld

26. Weld block (8) to the bottom side of the truck cab.

    Note: Ensure that you only weld along the short side of block (8) .

27. Repeat Step 26 for the one remaining block (8) .

28. Remove four bolts (9) and four washers (5) that were installed in Step 19. Retain all hardware.

29. Install the correct number of shims (15) that were measured in Step 23. Install shims (15) between walkway (2) and block (8) .

30. Repeat Step 29 for the one remaining block (8) .

31. Reinstall four bolts (9) and four washers (5) that were removed in Step 28.

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Illustration 44	g01394813
Front left hand view

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Illustration 45	g01394815
Front side view

32. Use a suitable lifting device in order to lift air cleaner (A) that was removed in Step 9 of the ""Removal of the Existing Parts" " section.

    Note: Air cleaner (A) weighs approximately 204 kg (450 lb).

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Illustration 46	g01404210

33. Install clamps (B) and clamp (C) that was removed in Step 10 of the section ""Removal of the Existing Parts" " in order to secure air cleaner (A) .

34. Install four bolts (D) and four washers (E) that were removed in Step 11 of the ""Removal of the Existing Parts" " section in order to secure air cleaner (A) .

35. Install four bolts (F) and four washers (G) that were removed in Step 12 of the ""Removal of the Existing Parts" " section in order to secure air cleaner (A) .

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Illustration 47	g01394845

36. Use a suitable lifting device in order to lift fender (H) that was removed in Step 1 of the ""Removal of the Existing Parts" " section.

    Note: Fender (H) weighs approximately 48 kg (106 lb).

37. Install nine bolts (J) and nine washers (K) that were removed in Step 1 of the ""Removal of the Existing Parts" " section in order to secure fender (H) .

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Illustration 48	g01431357

38. Remove four bolts (9), two bolts (6), and six washers (5). Retain washers (5) .

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Illustration 49	g01394863

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Illustration 50	g01431363

39. Install brace (16) with six bolts (17) and six washers (5) .

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Illustration 51	g01394895

40. Install handrail (18) with sixteen bolts (19), sixteen washers (20), four bolts (21), four washers (22), four bolts (23), and four washers (24) .

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Illustration 52	g01394988

41. Install handrail (25) with sixteen bolts (19) and sixteen washers (20) .

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Illustration 53	g01394993

42. Install bracket (26) with eight bolts (27) and eight washers (20) .

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Illustration 54	g01394995

43. Install bracket (28) with two blocks (29), four bolts (30), and four washers (20) .

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Illustration 55	g01394999

44. Use three bolts (19), three washers (20), and three weld nuts (31) in order to reinstall mirror (L) that was removed in Step 2 of the ""Removal of the Existing Parts" " section.