RT50 - RT60 Frame Stiffening{7001, 7051} Caterpillar

Introduction

Cracks may develop in the frame rails and/or boom towers of RT50, RT50 SA, RTC60 and RT60 Telescopic Material Handlers used in heavy duty applications. 8Q5365 Kit (RT50, RT50 SA and RTC60) or 8Q5366 Kit (RT60) is available to reinforce the frame and tower. This Special Instruction provides the necessary information needed to reinforce the frame and towers.

Do not perform any procedure, outlined in this publication, or order any parts until you read and understand the information contained within.

Chassis Frame Repair Kits

8Q5365 Chassis Frame Repair Kit (RT50, RT50 SA and RTC60 Models)

8Q5366 Chassis Frame Repair Kit (RT60 Models)

Welding Specifications

All welding is to be performed using one of the following specifications:

1. Manual Metallic Arc Welding - Low Hydrogen Electrodes.

COSA - BS 639:1976:E5153 B12(H)

NACD - AWS A5.1 E7018

2. MIG Welding Wire.

COSA - BS 2901 PT1.1983.A18

NACD - AWS ER70S-6

Frame Stiffening Procedure

1. Set hand brake and tag truck as non-operational.

2. Raise boom and install lock plate.

3. Steam clean the entire center area of the frame, the inner area of the boom towers and the boom pivot bracket area.

4. Unbolt the tilt compensating valve from the right frame rail.

5. Remove all clips and ties from all hoses, tubes and wire harnesses inside the center section of the frame.

6. Remove battery cable, fuel line and the two hydraulic hoses all of which pass through the top right hand hole in the rear bulkhead.

NOTE: Cap or plug all open hoses and fittings and tag all removed hoses and wires for location.

7. Disconnect all hoses from the side of the cab.

8. Cut off old tilt compensating valve mounting brackets and the three weld studs on the upper left rail.

9. Disconnect and remove the brake lines from the bulkhead fitting located on the upper left hand rail and remove the fitting. Plug the open lines.

10. Remove shift rod to transmission.

11. Remove drive shafts to improve welding accessibility.

12. Cover the right side of cab with plywood to prevent sparks from entering cab or marking the glass.

13. Before welding in an area, use rope to tie all hoses and wires as far away from that rail as possible.

NOTE: On the top of the rails, a 2X4 works well to keep the hoses away from the rail.

14. Generously cover all hoses and harnesses with soaking wet shop towels and then cover with welding leathers or non-flammable welding blankets. Be sure to protect shift boot.

15. Grind to remove paint from the areas to be welded.

NOTE: Some minor grinding may be required to clear existing welds.

Observe all normal welding precautions such as removing all burnable material from the area, having fire extinguishers handy, etc.

16. Before performing any welding, preheat weld areas to 100° C (212° F).

RT50, RT50 SA and RTC60 Models (8Q5365 Kit)

Illustration One.

1. Locate and clamp one 8Q2758 Stiffener (1) firmly in place on the right hand frame rail and weld according to the following instructions.

* Weld along the top and bottom of stiffener using an 8 mm (.31 in) fillet weld (A).

* Weld each end of stiffener using an 8 mm (.31 in) fillet (B).

2. Locate and clamp one 8Q2759 Stiffener (2) firmly in place on the left hand frame rail and weld according to the instructions used in Step One.

3. Magnaflux the four areas where the frame cross members attach to the frame rails, to ensure all existing cracks are found.

Illustration Two. (L) Grind Flush. Both Sides.

4. If any cracks exist in the chassis, repair using the following procedure.

a. Determine full extent of crack and grind out forming a single "V" groove as shown in illustration Two.

NOTE: If an existing crack extends past the rounded edge of the frame rail, it may be necessary to loosen the cab and/or hydraulic tank and move to the side to assure the complete crack is ground out and welded.

b. Preheat area of crack to 90° - 100° C (194 - 212° F) and weld solid.

c. Grind flush any crack repair welds.

5. Locate and clamp one 8Q2760 Stiffener (3) firmly in place on the top section of the right hand frame rail and weld according to the following instructions.

* Weld along the top and bottom of stiffener using an 8 mm (.31 in) fillet weld (C).

* Weld each end of stiffener using an 8 mm (.31 in) fillet (D).

6. Locate and clamp one 8Q2761 Stiffener (4) firmly in place on the top section of the left hand frame rail and weld according to the instructions in Step 5.

7. Locate and weld one 8Q2762 Pad (5), as shown, on the 8Q2760 Stiffener (3). Weld with two 25.4 mm (1 in) welds (V) along the top of pad (5) and a weld on each end.

8. Using the dimensions in the illustration, locate and clamp one 8Q5394 Angle Stiffener (8) firmly in place on the left frame rail as shown. Weld according to the following instructions.

* Weld to the left frame rail using a 6 mm (.24 in) fillet weld (E).

* Weld the top of stiffener (8) to the 8Q2761 Stiffener Top (4) with a 6 mm (.24 in) fillet weld (F) on each side of stiffener (8) in the area shown and also a 6 mm (.24 in) bevel groove weld (G) in the area shown.

* Weld the bottom of stiffener (8) to the 8Q2759 Stiffener (2) with a 6 mm (.24 in) fillet weld (F) on each side of stiffener (8) in the area shown and also a 6 mm (.24 in) bevel groove weld (G) in the area shown..

9. Locate and weld one 8Q6675 Plate (12) to the open side of 8Q5394 Angle Stiffener (8) as shown. Use a 6 mm (.24 in) fillet weld (H) along each side of plate (12) and a 6 mm (.24 in) fillet weld (J) at the top and bottom of plate (12).

10. Locate and weld one 897991 Plate (10) and one 815975 Stud (11) on the 8Q5394 Angle Stiffener LH (8) using the dimensions in the illustration.

11. Locate and clamp one 8Q5401 Angle Stiffener (9) firmly in place on the right hand frame rail and weld according to the following instructions.

* Weld to the right hand frame rail using a 6 mm (.24 in) fillet weld (K) on each side of angle stiffener.

* Weld to 8Q2760 Stiffener (3) using a 6 mm (.24 in) fillet weld (L) on each side of angle stiffener.

* Weld to 8Q2758 Stiffener (1) using a 6 mm (.24 in) bevel groove weld (M).

Illustration Three. (J) Cab Side. (K) Tank Side.

12. Locate and clamp one 8Q6799 Plate (13) firmly in place on top of the right frame rail as shown. Weld in place using the following instructions.

* Use an 8 mm (.31 in) fillet weld (N) to weld all around the plate.

* Use an 8 mm (.31 in) fillet weld (P) along the frame and under the section of plate (13) that protrudes over the edge of the frame.

13. Locate and clamp one 8Q6800 Plate (14) firmly in place on top of the left frame rail as shown. Weld in place using the following instructions.

* Use an 8 mm (.31 in) fillet weld (Q) to weld all around the plate.

* Use an 8 mm (.31 in) fillet weld (R) along the frame and under the section of plate (14) that protrudes over the edge of the frame.

14. Remove the muffler and protect all boom wire harnesses and hoses with wet rags and leathers.

NOTE: Refer to Illustration One for Steps 15 and 16.

15. Locate and clamp one 8Q2779 Stiffener "A" Frame (6) firmly in place on the front right hand side of the boom tower and weld according to the following instructions.

* Weld along each side of stiffener using an 8 mm (.31 in) fillet weld (S).

* Weld the bottom of stiffener using an 8 mm (.31 in) fillet (T).

* Weld the top of stiffener using an 8 mm (.31 in) bevel groove weld (U).

16. Locate and clamp one 8Q2780 Stiffener "A" Frame (7) firmly in place on the front left hand side of the boom tower and weld according to the instructions in Step 17.

17. Add weld studs or drill and tap holes to reclip hoses, brake lines and wire harnesses.

RT60 Models (8Q5366 Kit)

Illustration Four. RT60 Models (8Q5366 Kit). (G) Drain Hole. Leave clear of weld.

1. Locate and clamp one 8Q2776 Stiffener (1) firmly in place on the right hand frame rail and weld according to the following instructions.

* Weld along the top and bottom of stiffener using an 8 mm (.31 in) fillet weld (A).

* Weld each end of stiffener using an 8 mm (.31 in) fillet (B).

2. Locate and clamp one 8Q2777 Stiffener (2) firmly in place on the left hand frame rail and weld according to the instructions used in Step One.

3. Magnaflux the four areas where the frame cross members attach to the frame rails, to assure all existing cracks are found.

Illustration Five. (H) Grind Flush. Both sides.

4. If any cracks exist in the chassis, repair using the following procedure.

a. Determine full extent of crack and grind out forming a single "V" groove as shown in Illustration Five.

NOTE: If an existing crack extends past the rounded edge of the frame rail, it may be necessary to loosen the cab and/or hydraulic tank and move to the side to assure the complete crack is ground out and welded.

b. Preheat area of crack to 90° - 100° C (194 - 212° F) and weld solid.

c. Grind flush any crack repair welds.

5. Locate and clamp one 8Q2774 Stiffener (3) firmly in place on the top section of the right hand frame rail and weld according to the following instructions.

* Weld along the top and bottom of stiffener using an 8 mm (.31 in) fillet weld (C).

* Weld each end of stiffener using an 8 mm (.31 in) fillet (D).

6. Locate and clamp one 8Q2775 Stiffener (4) firmly in place on the top section of the left hand frame rail and weld according to the instructions in Step 5.

7. Remove the muffler and protect all boom wire harnesses and hoses with wet rags and leathers.

8. Locate and clamp one 8Q2779 Stiffener "A" Frame (5) firmly in place on the front right hand side of the boom tower and weld according to the following instructions.

* Weld along each side of stiffener using an 8 mm (.31 in) fillet weld (E).

* Weld the bottom of stiffener using an 8 mm (.31 in) fillet (F).

* Weld the top of stiffener using an 8 mm (.31 in) bevel groove weld (G).

9. Locate and clamp one 8Q2780 Stiffener "A" Frame (6) firmly in place on the front left hand side of the boom tower and weld according to the instructions in Step 8.

10. Add weld studs or drill and tap holes to reclip hoses, brake lines and wire harnesses.

All Models

1. Clean and paint all new supports and welded areas.

2. Reform brake line to follow the top side of the new support on the lower left rail.

3. Install or connect all the hoses, lines and cables which were disconnected.

4. Bleed the brakes, test the truck and check for leaks. Refer to the Service Manual for procedure to bleed the brakes.

5. Check the boom pivot bracket welds for cracks and, if necessary, repair in accordance with P.S.P. PS0581.