Procedure to Retrofit a Rear Cab Walkway onto Certain 793, 793B, and 793C Off-Highway Trucks {7253, 7254, 7255, 7256} Caterpillar

Truck

793 (S/N: 3SJ1-UP)

793B (S/N: 1HL1-UP)

793C (S/N: CBR1-UP; 4AR1-UP; ATY1-UP; 4GZ1-UP)

Introduction

Do not perform any procedure in this Special Instruction until you have read the information and you understand the information.

The following procedure includes all the required parts and instructions needed to install the 499-5373 Operator Platform Kit and the 493-0527 Walkway Assembly Retrofit Kit for a rear cab walkway onto certain 793, 793B, and 793C Off-Highway Trucks.

The 499-5373 Operator Platform Kit and the 493-0527 Walkway Assembly Retrofit Kit includes all the required parts.

Note: The 493-0527 Walkway Assembly Retrofit Kit is part of the 499-5373 Operator Platform Kit.

Machine Preparation

1. Prepare the machine for maintenance.

2. Park the machine on a dry, level, solid surface that is free of debris.

3. Move the transmission control into the P position and engage the parking brakes.

4. Raise the truck body and install the body retaining cable.

5. Turn the key start switch and the disconnect switch to the OFF position.

6. Place wheel chocks in front of and behind the wheels.

Required Parts

Fabrication Procedure

Fabrication - Rear Walkway Assembly

Note: The following fabrication to the rear walkway assembly is only needed if 456-0266 Walkway As (1) is received at change level 02.

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Illustration 1	g06004750
View of the 456-0266 Walkway As (1) ( 1) 456-0266 Walkway As (A) 13.5 mm (0.531 inch) by 24 mm (0.944 inch) hole (AA) 7 mm (0.275 inch) Radius (two places) (AB) 74 mm (2.913 inch) (AC) 23 mm (0.905 inch)

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Illustration 2	g06004258
View of the 456-0266 Walkway As

1. Fabricate walkway assembly (1) by adding material to walkway assembly (1) as shown in Illustration 1 and Illustration 2.

   Repaint the fabrication area, as needed.

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   Illustration 3	g06007174
   View of the 456-0266 Walkway As (AD) 39.5 mm (1.55 inch) (AE) 39.5 mm (1.55 inch) (AF) 49.4 mm (1.94 inch) (AG) 13.8 mm (0.543 inch) diameter hole (two)

2. Drill two 13.8 mm (0.543 inch) diameter holes into the 456-0266 Walkway As in the locations shown in Illustration 3.

   Note: The 451-5975 Plate can be used to help locate the holes.

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   Illustration 4	g06007202
   View of the 456-0266 Walkway As (2) 8T-3490 Weld Nut

   Note: Refer to Special Instruction, REHS1841, "General Welding Procedures" prior to performing any welding on the machine.

3. Prepare the area for welding.

   Weld two nuts (2) to the 456-0266 Walkway As as shown in Illustration 4.

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   Illustration 5	g06007258
   View of the 456-0266 Walkway As (AH) 261.7 mm (10.30 inch) (AJ) 122.5 mm (4.82 inch) (AK) 13.8 mm (0.543 inch) diameter hole

4. Drill a 13.8 mm (0.543 inch) diameter hole into the 456-0266 Walkway As in the location shown in Illustration 5.

   Note: The 451-5970 Plate can be used to help locate the hole.

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   Illustration 6	g06007270
   View of the 456-0266 Walkway As (2) 8T-3490 Weld Nut

   Note: Refer to Special Instruction, REHS1841, "General Welding Procedures" prior to performing any welding on the machine.

5. Prepare the area for welding.

   Weld nut (2) to the 456-0266 Walkway As as shown in Illustration 6.

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   Illustration 7	g06007275
   View of the 456-0266 Walkway As (AL) 61.24 mm (2.41102 inch) (AM) 59 mm (2.32 inch) (AN) 89 mm (3.50 inch) (AP) 13.8 mm (0.543 inch) diameter hole (two)

6. Drill two 13.8 mm (0.543 inch) diameter holes into the 456-0266 Walkway As in the location shown in Illustration 7.

   Note: One hole is above the platform, and one hole is below the platform.

   Note: The 451-5969 Plate can be used to help locate the holes.

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   Illustration 8	g06007956
   View of the 456-0266 Walkway As (2) 8T-3490 Weld Nut

   Note: Refer to Special Instruction, REHS1841, "General Welding Procedures" prior to performing any welding on the machine.

7. Prepare the area for welding.

   Weld two nuts (2) to the 456-0266 Walkway As as shown in Illustration 8.

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   Illustration 9	g06007994
   View of the 456-0266 Walkway As (AR) 87 mm (3.42 inch) (AS) 124 mm (4.88 inch) (AT) 509 mm (20.04 inch) (AU) 13.8 mm (0.543 inch) diameter hole (two)

8. Drill two 13.8 mm (0.543 inch) diameter holes into the 456-0266 Walkway As in the location shown in Illustration 9.

   Note: The 451-5968 Plate can be used to help locate the holes.

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   Illustration 10	g06008007
   View of the 456-0266 Walkway As (2) 8T-3490 Weld Nut

   Note: Refer to Special Instruction, REHS1841, "General Welding Procedures" prior to performing any welding on the machine.

9. Prepare the area for welding.

   Weld two nuts (2) to the 456-0266 Walkway As as shown in Illustration 10.

Fabrication - Mud Guard

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Illustration 11	g06004861
View of the 451-5972 Guard (3) ( 3) 451-5972 Guard (AA) 780 mm (30.70 inch) (AB) 758 mm (29.84 inch) (AC) 723 mm (28.46 inch) (AD) 520 mm (20.47 inch) (AE) 366.5 mm (14.42 inch) (AF) 285.5 mm (11.24 inch) (AG) 50 mm (1.96 inch) (AH) 537 mm (21.14 inch) (AJ) 387 mm (15.23 inch) (AK) 237 mm (9.33 inch) (AL) 402.5 mm (15.84 inch) (AM) 322.5 mm (12.69 inch) (AN) 242.2 mm (9.53 inch) (AP) 101.6 mm (4 inch) (AR) 190.5 mm (7.5 inch) (AS) 380 mm (14.96 inch) (AT) 304 mm (11.96 inch) (AU) 227.5 mm (8.95 inch) (AV) 241.3 mm (9.5 inch) (AW) 647 mm (25.5 inch)

1. Modify the guard (3) as shown in Illustration 11.

   Note: All holes are 13.8 mm (0.543 inch) in diameter.

   Note: The mounting plates should be used to help align the holes. Refer to Step 9 for the alignment of the mud guard and the location of the holes.

Fabrication - Handrail Assembly

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Illustration 12	g06008154
View of the left-hand handrail assembly (A) Center tube of the handrail assembly (AA) 305 mm (12.00 inch) (two places)

1. Cut and remove the rear side of the handrail assembly. Remove and discard the hardware that secures the rear section of the handrail assembly.

   Note: Dimension (AA) must be measured from the rear side of center tube (A).

Fabrication - Left-Hand Walkway Assembly

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Illustration 13	g06009613
(AB) 50.8 mm (2.00 inch) (AC) 13.7 mm (0.54 inch) (AD) 49 mm (1.93 inch) (AE) 63.5 mm (2.50 inch) (AF) 13.8 mm (0.543 inch) diameter hole (four)

1. Drill four holes through the left-hand walkway assembly.

Fabrication - Guard Mounting Plate

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Illustration 14	g06038382
View of the 451-5975 Plate (16) ( 16) 451-5975 Plate (AA) 101.6 mm (4 inch)

1. Modify plate (16) to remove 101.6 mm (4 inch) from the end, as shown in Illustration 14.

Fabrication - Guard Mounting Plate

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Illustration 15	g06038445
View of the 451-5968 Plate (17) ( 17) 451-5968 Plate (AA) 38.1 mm (1.5 inch)

1. Modify plate (17) to remove 38.1 mm (1.5 inch) from the end, as shown in Illustration 15.

Installation Procedure

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Illustration 16	g06004167

1. Remove and discard mud flap (A).
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   Illustration 17	g06004178

2. Remove the hardware that secures the left-hand rear support for the cab to the bottom of the cab. Discard all the mounting hardware.
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   Illustration 18	g06004186

3. Attach a suitable lifting device to the rear cab mounting. The approximate weight of the rear cab mounting is 260 kg (575 lb).

   Remove the hardware that secures the rear cab mounting to the frame and remove the rear cab mounting. Discard the rear cab mounting and all associated hardware.

   Note: Some oxidation and corrosion may be visible inside the removed rear cab mounting. The oxidation and corrosion are normal and should not be cause for alarm.

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   Illustration 19	g06004188
   View of the support assembly (1) 346-1157 Support As

4. Locate support assembly (1).

   Note: The approximate weight of support assembly (1) is 260 kg (575 lb).

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   Illustration 20	g06004190
   View of the support assembly (1) 346-1157 Support As

5. Prepare support assembly (1) for installation. Remove paint, rust, scale, or debris from all mounting surfaces.

   Note: Do not use a grinding pad on the surfaces.

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   Illustration 21	g06004967
   Typical view of the support assembly (1) 346-1157 Support As (2) 1B-2721 Bolt (3) 5T-1352 Spacer (4) 2H-1537 Bolt

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   Illustration 22	g06004196
   View of the support assembly (1) 346-1157 Support As (5) 1K-9420 Bolt (6) 5T-5807 Retainer (7) 163-0042 Mount (8) 163-0364 Sleeve

6. Install support assembly (1) onto the frame by using six bolts (2), 12 spacers (3), and six bolts (4).

   Note: Newer frames have metric threads. For older frames, new bolts (2) and new bolts (4) will not work. Refer to the Parts Manual for your machine for the correct hardware to mount support assembly (1).

   Secure support assembly (1) to the bottom of the cab by using six bolts (5), six retainers (6), 12 mounts (7), and six sleeves (8).

   Note: Apply Loctite 242 to the threads of bolts (5). Tighten bolts (5) to 1904 ± 68 N·m (1400 ± 50 lb ft).

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   Illustration 23	g06005964
   (9) 456-0266 Walkway As (10) 8T-4139 Bolt (11) 8T-4223 Hard Washer

7. Attach a suitable lifting device to walkway assembly (9).

   Note: The approximate weight of walkway assembly (9) is 46 kg (101 lb).

   Secure walkway assembly (9) to the support assembly by using 12 bolts (10) and 12 hard washers (11).

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   Illustration 24	g06008073
   (9) 456-0266 Walkway As (12) 8T-4136 Bolt (13) 8T-4121 Hard Washer (14) 451-5970 Plate (15) 451-5969 Plate (16) 451-5975 Plate (17) 451-5968 Plate

8. Secure plate (14) to walkway assembly (9) by using bolt (12) and hard washer (13).

   Secure plate (15) to walkway assembly (9) by using two bolts (12) and two hard washers (13).

   Secure plate (16) to walkway assembly (9) by using two bolts (12) and two hard washers (13).

   Secure plate (17) to walkway assembly (9) by using two bolts (12) and two hard washers (13).

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   Illustration 25	g06008100
   Top view (13) 8T-4121 Hard Washer (14) 451-5970 Plate (15) 451-5969 Plate (16) 451-5975 Plate (17) 451-5968 Plate (18) 451-5972 Guard (19) 8T-0722 Locking Bolt (20) 8T-4133 Nut (21) 379-8131 Plate (22) 371-5816 Strip (23) 451-5974 Strip (24) 355-8576 Plate (25) 8T-4195 Bolt (26) 451-5962 Strip

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   Illustration 26	g06008102
   Bottom view (13) 8T-4121 Hard Washer (18) 451-5972 Guard (19) 8T-0722 Locking Bolt (20) 8T-4133 Nut (21) 379-8131 Plate (22) 371-5816 Strip (23) 451-5974 Strip (24) 355-8576 Plate (25) 8T-4195 Bolt (26) 451-5962 Strip

9. Secure modified guard (18) to the rear of the catwalk assembly and the plates by using the following hardware:

   • 30 Hard washers (13)

   • 11 Locking bolts (19)

   • 15 Nuts (20)

   • Plate (21)

   • Strip (22)

   • Strip (23)

   • Plate (24)

   • Four bolts (25)

   • Strip (26)

   Note: Strip (23) and strip (24) will require modification to fit correctly.

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   Illustration 27	g06009641
   View of the left-hand side walkway assembly (13) 8T-4121 Hard Washer (27) 486-3867 Handrail As (28) 486-3871 Plate (29) 486-3870 Plate (30) 8T-4186 Bolt (31) 344-5675 Nut

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   Illustration 28	g06009647
   View of the bottom of handrail assembly (27) ( 13) 8T-4121 Hard Washer (27) 486-3867 Handrail As (28) 486-3871 Plate (29) 486-3870 Plate (30) 8T-4186 Bolt (31) 344-5675 Nut

10. Secure handrail assembly (27) to the left-hand walkway assembly by using four bolts (30), eight hard washers (13), four nuts (31), plate (28), and plate (29).

11. Weld handrail assembly (27) to the existing left-hand handrail assembly.
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    Illustration 29	g06006092
    (13) 8T-4121 Hard Washer (32) 456-0270 Handrail As (33) 8T-5005 Bolt (34) 1F-7854 Spacer (35) 8T-0389 Locknut

12. Secure handrail assembly (32) to the catwalk assembly by using two bolts (33), four hard washers (13), two spacers (34), and two locknuts (35).
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    Illustration 30	g06006124
    (32) 456-0270 Handrail As (36) 5L-3946 Rod End (37) 9S-8752 Full Nut (38) 8T-4896 Hard Washer (39) 296-5446 Spring

13. Secure rod end (36) to the catwalk assembly by using two nuts (37) and two hard washers (38).

    Secure spring (39) between rod end (36) and the bottom of handrail assembly (32).

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    Illustration 31	g06009754
    (11) 8T-4223 Hard Washer (32) 456-0270 Handrail As (40) 6V-1874 Grommet (41) 5P-7468 Clip (42) 5P-7469 Clip (43) 438-9871 Plate (44) 456-0271 Plate (45) 8T-4956 Bolt (46) 329-3356 Nut (47) 160-9925 Lanyard (48) 5P-7958 Cable Splice Sleeve (49) 5C-9553 Bolt (50) 344-5673 Nut (51) 9X-8256 Washer (52) 172-8125 Pin

14. Secure plate (43) to the rear of the left-hand handrail assembly by using two grommets (40), two clips (41), two clips (42), two bolts (45), four hard washers (11), and two nuts (46).

    Secure plate (44) to the center tube of the left-hand handrail assembly by using two grommets (40), two clips (41), two clips (42), two bolts (45), four hard washers (11), and two nuts (46).

    Secure lanyard (47) to handrail assembly (32) by using bolt (49), nut (50), and washer (51).

    Secure lanyard (47) around pin (52) by using cable splice sleeve (48). Insert pin (52) into handrail assembly (32).

Register the Retrofit

Because retrofits to a prime product will change the configuration of the product, updating the configuration in SIMSi and AIMS is important. If the retrofit information is not provided, Caterpillar will not be able to provide important product updates.

The following information includes instructions on registering the updates and retrofits.

1. When performing a retrofit installation, record the vital information in Table 4.

   Note: If the procedure is performed by the customer, ask the customer to record the proper information.

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   Table 4

   Repair Date
   Product Serial Number
   Service Hours or Service Meter Units
   Removed Component Part Number(1)
   Removed Component Serial Number(1)
   Installed Component Part Number(2)
   Installed Component Serial Number(3)

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   (1)	Only applies if a component is replaced by a retrofit component. If the product is an engine, and the product retrofit is a kit for upgrading the engine, disregard the "Removed Component" information. Refer to detailed instructions in Step 3 for more information.
   (2)	Record the highest level retrofit kit, arrangement, or group part number.
   (3)	Most retrofits will not have a serial number. Exceptions include emissions repower engines and diesel particulate filters.

2. Update the product configuration by entering the information from Table 4 into SIMSi and AIMS.

   Note: For retrofits that have a Caterpillar serial number, the AIMS application is "JIZ111-08". For retrofits that do not have a Caterpillar serial number, the AIMS application is "JIZ111-07".

3. For detailed instructions on updating the product configuration, refer to Special Instruction, REHS5097, "Instructions to Register the Retrofit".