- Off-Highway Truck/Tractor:
- 785C (S/N: 1HW1-UP; APX1-UP; 5AZ1-UP)
- 785D (S/N: MSY1-UP)
- 789C (S/N: 2BW1-UP)
- 789D (S/N: SPD1-UP; SHH1-UP)
- 785D (S/N: MSY1-UP)
Introduction
ReferenceSpecial Instruction, REHS1841, "General Welding Procedures"
The ejector assemblies on some 785 and 789 bodies require a longer rock ejector. This procedure applies to the modification and lengthening of the short ejector assemblies.
Important Safety Information
The following information is an explanation of various labels that are found in this document.
Warnings
The warning label informs the technician that an injury or death can occur as a result of a condition that may exist.
Notices
A notice informs the technician that component damage can occur as a result of a condition that exists.
Notes
A note contains general information for the technician about the operation that is being performed.
Proper repair is important to the safe operation and the reliable operation of this machine. This document outlines basic recommended procedures. Some of the procedures require special tools, devices, or work methods.
Before you perform any repairs or before you perform any maintenance, read all safety information. Understand all safety information before you perform any repairs or before you perform any maintenance.
Safety information is provided in this document and on the machine. If these hazard warnings are not heeded, bodily injury or death could occur to you or other persons.
The "Safety Alert Symbol" that is followed by a "Signal Word" identifies a hazard. "DANGER", "WARNING", and "CAUTION" are "Signal Words".
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| Illustration 1 | g00008666 |
The signal word "WARNING" has the following meanings:
- Pay Attention !
- Become Alert !
- Your Safety Is Involved !
The message that appears under the safety alert symbol explains the hazard.
Operations or conditions that may cause product damage are identified by "NOTICE" labels on the machine and in the service information.
The person that services the machine may be unfamiliar with many of the systems on the machine. Use caution when you perform service work. Special knowledge of the systems and of the components is important. Before you remove or disassemble any component, obtain knowledge of the system and knowledge of the component.
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. Determine that the operation, lubrication, maintenance, and repair procedures will not make the machine unsafe.
Basic Precautions
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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. |
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Always observe the list of basic precautions that follows:
Safety Signs
Safety signs include the items that follow: signs, information plates and decals. Read all "Safety" signs on the machine before operating, lubricating, or repairing the machine. Understand all "Safety" signs on the machine before operating, lubricating, or repairing the machine. Replace any safety signs that are in the conditions that follow: damage, unreadable and missing.
Protective Equipment
When you work around the machine, always wear protective equipment that is required by the job conditions. Protective equipment includes the items that follow: hard hat, protective glasses and protective shoes. In particular, wear protective glasses when you use a hammer or when you use a sledge hammer. When you weld, use the appropriate protective equipment that is required by the job conditions. Protective equipment for welding includes the items that follow: gloves, welding hood, goggles and apron. Do not wear loose clothing or jewelry that can catch on parts of the machine.
Mounting and Dismounting
Use steps and handholds when you mount a machine. Also, use steps and handholds when you dismount a machine. Before you mount the machine, clean any mud or debris from steps, walkways, or work platforms. Always face the machine when you use steps, handholds, and walkways. When you cannot use the accesses on the machine, use ladders, scaffolds, or work platforms to perform safe repair operations.
Specifications for Cables, Chains, and Lifting Devices
Use approved cables, chains, and lifting devices in order to lift components. Refer to the manufacturer's weights 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 Caterpillar parts.
Note: Ensure that the hooks are equipped with a safety latch. Do not place a side load on the lifting eyes during a lifting operation.
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| Illustration 2 | 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. | |
Hot Fluids and Parts
To avoid burns, be alert for hot parts on machines which have been stopped and hot fluids in lines, tubes and compartments.
Be careful when you remove filler caps, breathers, and plugs on the machine. Hold a rag over the cap or plug in order to prevent being sprayed by pressurized liquids. When the machine has been stopped, the danger of hot fluids is greater.
Corrosion Inhibitor
Corrosion inhibitor contains alkali. Avoid contact with the eyes. Do not allow corrosion inhibitor to contact the skin for extended periods of time. Avoid repeated contact with the skin. Do not drink corrosion inhibitor. In case of contact, immediately wash skin with soap and water. For contact with the eyes, flush the eyes with large amounts of water for at least 15 minutes. Seek medical attention.
Batteries
Do not smoke when an inspection of the battery electrolyte level is made. Never disconnect any charging unit circuit or battery circuit cable from the battery when the charging unit is operating. A spark can cause an explosion from the flammable vapor mixture of hydrogen and oxygen that is released from the electrolyte through the battery outlets. Do not allow battery electrolyte to contact skin or eyes. Battery electrolyte is an acid. In case of contact with battery electrolyte, immediately wash the skin with soap and water. For contact with the eyes, flush the eyes with large amounts of water for at least 15 minutes. Seek medical attention.
Pressurized Items
- Always use a board or a piece of cardboard when you check for a leak. Leaking fluid under pressure can penetrate body tissue. Fluid penetration can cause serious injury and possible death. A pin hole leak can cause severe injury. If fluid is injected into your skin, you must get treatment immediately. Seek treatment from a doctor that is familiar with this type of injury.
- Relieve all pressure in air, oil, or water systems before any lines, fittings, or related items are disconnected or removed. Always make sure that all raised components are blocked correctly. Be alert for possible pressure when you disconnect any device from a system that utilizes pressure.
- Fuel lines that are damaged and fuel lines that are loose can cause fires. Lubrication lines that are damaged and lubrication lines that are loose can cause fires. Hydraulic lines, tubes, and hoses that are damaged can cause fires. Loose hydraulic lines, loose tubes, and loose hoses can cause fires. Do not bend or strike high-pressure lines. Do not install lines which have been bent or damaged. Check lines, tubes, and hoses carefully. Do not use your bare hand to check for leaks. If fluids are injected into your skin, you must get treatment immediately. Seek treatment from a doctor that is familiar with this type of injury.
- Pressure air or water can cause personal injury. When pressure air or water is used for cleaning, wear a protective face shield, protective clothing, and protective shoes. The maximum air pressure for cleaning purposes must be below 205 kPa (30 psi). When you use a pressure washer, keep in mind that the nozzle pressures are high. The nozzle pressures are frequently above 13790 kPa (2000 psi). Follow all of the recommended practices that are provided by the manufacturer of the pressure washer.
Welding Specifications and Qualifications
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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 kill. Read and understand the manufacturer's instruction and your employer's safety practices. Keep your head out of the fumes. Use ventilation, exhaust at the arc, or both, to keep fumes and gases from your breathing zone and the general area. Wear correct eye, ear and body protection. Do not touch live electric parts. Refer to the American National Standard Z49.1, "Safety in Welding and Cutting" published by the American Welding Society, 2501 N.W. 7th Street, Miami, Florida 33125: OSHA Safety and Health Standards, 29 CFR 1910, available from U.S. Dept. of Labor, Washington D.C. 20210. |
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Note: Personal breathing protection should be worn by the personnel that are welding. Personal breathing protection will prevent fumes from entering the lungs of the person that is welding. Use a 237-5181 Respirator for breathing protection.
Qualifications
Welders must be qualified for the appropriate type of weld that is being performed. Welders must be qualified for the appropriate position of weld that is being performed. Welders must be qualified for the welding process that is being utilized: Shielded Metal Arc Welding (SMAW) and Flux Cored Arc Welding (FCAW). Refer to Specification ANSI/AWS D1.1 for information that regards qualification requirements. The welders must have used the process at some time within the last 6 months. The welders must complete the process of certification if the welders have not used the welding processes for 6 months.
Proper Welding Procedure on Machines and Engines with Electronic Controls
Proper precautions are necessary to prevent damage to electronic controls. When you weld on a machine with electronic controls, use the steps that follow:
- Turn off the engine. Put the key start switch in the OFF position.
- If the machine has a battery disconnect switch, open the switch. If the machine does not have a battery disconnect switch, disconnect the negative battery cable at the battery.
- Attach the clamp for the ground cable as close as possible to the area that is being welded. This process will reduce the likelihood of damage from the welding current to the following components: bearings, hydraulic components, and electrical components. DO NOT weld plates to the frame for grounding/clamping purposes. Use existing blocks, brackets, bosses, and so on, to attach the clamp.
Note: Do NOT use electrical components as a ground point for the welder. Do NOT use ground points for electronic components as a ground point for the welder.
- Protect the wiring harnesses and machine surfaces from sparks and welding spatter.
Area Preparation
The area to be welded shall be clean, dry, and free of the following contaminants:
- Oil
- Grease
- Paint
- Dirt
- Rust
- Any fluids or moisture
All welding shall be conducted on base material heated and maintained at a minimum temperature of 15.6° C (60° F).
Note: Heating instructions (preheat, interpass, and postheat) for any specific repair shall override the minimum 15.6° C (60° F) requirement.
Note: Heat distortion of the base metal is possible when you weld. Avoid excessive heating of the base metal.
Welding Electrodes and Parameters
Flux Cored Welding Electrode for the FCAW Process
Use the Flux Cored Arc Welding (FCAW) with E71T-1 H8 (ANSI/A5.20) welding electrode and the manufacturer's shielding gases that are specified (typically 75% argon and 25% carbon dioxide). The H8 implies that the electrode is designed to provide less than 8 ml/100 g of diffusible hydrogen in the weld deposit. The weld that is deposited by the flux cored welding electrode will have the following minimum mechanical properties:
| Mechanical Properties from Flux Cored Welding Electrode That Is Classified as "ANSI/AWS A5.20 E71T-1 H8" | |
|---|---|
| Tensile Strength | 480 MPa (70000 psi) |
| Yield Strength | 400 MPa (58000 psi) |
| Elongation | 22% |
| Impact Toughness | 27 J @ -18 °C (20 ft lb @ -0 °F) |
The tables that follow show the recommended parameter ranges for out of position welding in the field for two different flux cored welding electrode diameters.
| Welding Current for Flux Cored Welding Electrode that Is 1.2 mm (0.045 inch) |
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|---|---|---|
| Wire Feed Rate | Voltage | Amperage |
7620 mm (300 inch) Per Minute to 10,160 mm (400 inch) Per Minute |
24 to 28 | 190 to 240 |
| Welding Current for Flux Cored Welding Electrode that Is 1.4 mm (0.052 inch) |
||
|---|---|---|
| Wire Feed Rate | Voltage | Amperage |
5080 mm (200 inch) Per Minute to 6350 mm (250 inch) Per Minute |
23 to 27 | 180 to 220 |
Note: The settings listed above are recommendations-based on experience from welding in the horizontal, vertical-up, and overhead positions. Slight changes in the voltage and amperage may be necessary due to welding position and various formulations by different electrode manufacturers. The use of higher parameters than specified for welding in the flat position is acceptable.
Use a polarity setting of DC reverse polarity. Remove the slag after each welding pass. The fast freezing characteristics of flux cored welding electrode increases the possibility of evolving gas that is trapped in the weld. Control the size of the weld in order to reduce the possibility of evolving gas that is trapped in the weld. The maximum size weld per pass shall be equivalent to that of a 8.0 mm (.32 inch) fillet weld.
Low Hydrogen Electrodes for the SMAW Process
As an alternative process or when wind conditions are a factor, use SMAW and low hydrogen electrodes that meet the following requirements.
| Mechanical Properties of Welds from Low Hydrogen Electrodes That Are Classified as "ANSI/AWS A5.1 E7018H4R" | |
|---|---|
| Tensile Strength | 480 MPa (70000 psi) |
| Yield Strength | 400 MPa (58000 psi) |
| Elongation | 22% |
| Impact Toughness | 27 J @ -29 °C (20 ft lb @ -20 °F) |
Low hydrogen electrodes must be stored in an electrode oven at 120 °C (250 °F) when not in use. If low hydrogen electrodes get damp, scrap the low hydrogen electrodes or recondition the low hydrogen electrodes to the manufacturer's specifications.
The table that follows shows the settings for the welding current based on electrode diameter.
| Welding Current for Low Hydrogen Electrodes | |
|---|---|
| Diameter | Amperage Rating |
| 3.2 mm (1/8 inch) | 105-155 |
| 4.0 mm (5/32 inch) | 130-200 |
| 4.8 mm (3/16 inch) | 200-275 |
Use a polarity setting of DC reverse polarity. Remove the slag after each pass of the welding electrode. The width of the weld shall not exceed two times the electrode diameter.
Weld Inspection and Acceptance Criteria
| Defect Name | ISO 6520 Defect Reference Number | Remarks | Defect Limit |
| Cracks - Longitudinal, Transverse, Radiating, Crater, Disconnected, Branching | 1011, 1012, 1013, 1014, 1023, 1024, 1031, 1033, 1034, 1045, 1046, 1047, 1051, 1053, 1054, 1061, 1063, 1064 | -- | Not Permitted |
| Crack - Transverse | 1021 | Hard Surfacing Welds Only | Permitted |
| Crack - Transverse | 1021 | Joining Welds | Not Permitted |
| Porosity | 2011, 2012, 2014, 2017 | Maximum Diameter for a Single Pore | 1 mm (0.040 inch) |
| Maximum Pores in Any 300 mm (11.81 inch) Length of Weld |
6 | ||
| Maximum Number of Pores in Any 50 mm (2.0 inch) of Weld Length for Welds Less Than 300 mm (11.81 inch) in Length |
1 | ||
| Clustered Porosity | 2013 | Maximum Length of Cluster in Any Weld | 3 mm (0.120 inch) |
| Elongated Cavities | 2015 | Maximum Height or Width | 3 mm (0.120 inch) |
| Maximum Length for Any Single Discontinuity | 25 mm (1.00 inch) |
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| Maximum Length in Any Weld | 10% of Weld Length | ||
| Elongated Cavities | 2016 | Maximum Dimension of Any Single Cavity | 3 mm (0.120 inch) |
| Maximum Total Length of Affected Area in Any Weld | 10% of Weld Length Not to Exceed 25 mm (1.00 inch) |
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| Shrinkage Cavities | 2021, 2024, 2025 | Maximum Diameter or Length | 1 mm (0.040 inch) |
| Slag or Flux Inclusions | 3011, 3012, 3014, 3021, 3022, 3024 | Maximum Height or Width | 1 mm (0.040 inch) |
| Maximum Length for Any Single Discontinuity | 25 mm (1.00 inch) |
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| Maximum Length in Any Weld | 10% of Weld Length | ||
| Oxide Inclusions | 3031, 3032, 3033 | Maximum Height or Width | 1 mm (0.040 inch) |
| Maximum Length for Any Single Discontinuity | 25 mm (1.00 inch) |
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| Maximum Length in Any Weld | 10% of Weld Length | ||
| Puckering (Oxide Inclusion - Aluminum) | 3034 | -- | Not Permitted |
| Metallic Inclusion | 3041, 3042, 3043 | -- | Not Permitted |
| Lack of Fusion | 4011, 4012, 4013 | Visual (Breaking the Surface) | Not Permitted |
| Subsurface Maximum Height or Width | 1 mm (0.040 inch) |
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| Subsurface Maximum Length for Any Single Discontinuity | 25 mm (1.00 inch) |
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| Maximum Length in Any Weld | 10% of Weld Length | ||
| Lack of Penetration | 402, 4021 | Maximum Reduced Penetration | 10% of Nominal Penetration Not to Exceed 1 mm (0.040 inch) |
| Maximum Allowed Total Length of Reduced Penetration | 10% of Weld Length | ||
| Undercut | 5011, 5012, 5013, 5014, 5015 | Maximum Depth Measured From Plate Surface - Any Length | 0.5 mm (0.020 inch) |
| Excess Weld Metal - Groove Weld Reinforcement (Convexity) | 502 | Any Length | -- |
| Weld Face Width 5 mm (0.20 inch) or Less |
1 mm (0.040 inch) |
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| Weld Face Width Over 5 mm (0.20 inch) But Less Than 10 mm (0.40 inch) |
1.5 mm (0.060 inch) |
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| Weld Face Width Over (10 mm)(0.40 inch) But Less Than 20 mm (0.80 inch) |
2 mm (0.080 inch) |
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| Weld Face Width Over 20 mm (0.80 inch) But Less Than 30 mm (1.20 inch) |
3 mm (0.120 inch) |
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| Weld Face Width 30 mm (1.20 inch) and Over |
4 mm (0.160 inch) |
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| Excess Weld Metal - Fillet Weld Convexity | 503 | Convexity Affects Weld Toe Angle, Reducing Fatigue Life | 90 Degrees |
| Weld Toe Angles of 135 Degrees and More Are Better | -- | ||
| Defect Limits Expressed as Minimum Toe Angles Allowed | -- | ||
| Excess Penetration | 5041, 5042, 5043 | Without Drawing Limitation | 2 mm (0.080 inch) (Any Length) |
| With "Melt - Thru" and "Flush" Weld Symbols | 1 mm (0.040 inch) (Any Length) |
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| With "Melt - Thru" and "Grind Flush" Symbols | Not Permitted (After Grinding) | ||
| Incorrect Weld Toe | 505 | When 1E2995 Applies (Expressed as a Toe Radius Rather Than a Toe Angle) | 3 mm (0.120 inch) Minimum Radius |
| Overlap | 5061, 5062 | Expressed as Minimum Toe Angle | 90 Degrees |
| Fillet Weld Leg Size - Undersize | -- | Applies to Either Weld Leg Measured Independent of the Other | -- |
| Maximum Undersize | 1 mm (0.040 inch) |
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| Maximum Length of Undersize Weld | 10% of Total Weld Length If At Least 10% of Total Weld Length is at Least 1 mm (0.040 inch) Over Nominal Size, Otherwise, No Undersize Length is Permitted |
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| Fillet Weld Leg Size - Oversize | -- | Applies to Either Weld Leg Measured Independent of the Other | -- |
| Maximum Oversize | +25% (max 3 mm (0.120 inch)) |
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| Conformance to Design - Fillet Weld Leg Sizes May be Oversized (Within Defect Limitations or Beyond) Without Correction Provided the Excess Does not Interfere with Satisfactory End Use of the Component (i.e., Distortion, Fit-Up Interference, etc.) | -- | ||
| Fillet Weld - Linear Length when specified at less than the length of the joint | -- | Weld Size ≤ 6.5 mm (0.256 inch) |
± 6.5 mm (0.256 inch) |
| Weld Size ≥ 6.5 mm (0.256 inch) |
± 12.5 mm (0.492 inch) |
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| Fillet Weld Throat Size - Undersize | 5213 | Nominal Size (0.7 x Leg Size) Not Inclusive of Penetration Beyond the Weld Root | Not Permitted |
| Weld Crater Only - Maximum Undersize | 2 mm (0.080 inch) MAX - and Not to Exceed 20% of Specified Throat, Not Inclusive of Penetration Beyond the Weld Root (0.7 x Leg Size) |
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| Incompletely Filled Groove Weld | 511 | Careful Consideration Needs to be Given When Plate Mismatch is Apparent | Not Permitted |
| Weld Depth Must be Maintained as a Minimum | -- | ||
| Root Concavity on Open Root Groove Welds | 515, 5013 | Maximum Depth measured From Plate Surface or Tube Inner Surface - Any Length | 0.5 mm (0.020 inch) |
| Poor Restart (Tie - In) | 5171, 5172 | Measured in Terms of Excess Weld Metal (Fillet Weld Convexity) or Overlap on Groove Welds, Lack of Fusion, or Insufficient Throat | -- |
| Excess Weld Metal on Fillet Welds, Defect Limits Expressed as Minimum Toe Angles Allowed | 90 Degrees | ||
| Overlap on Groove Welds, Defect Limits Expressed as Minimum Toe Angles Allowed | 90 Degrees | ||
| Lack of Fusion - Visual Maximum Length Per Restart | 3 mm (0.120 inch) |
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| Insufficient Weld Throat | Not Permitted | ||
| Stray Arc Strike | 601 | -- | Not Permitted |
| Slag Residue | 615 | SMAW, SAW, FCAW, GMAW | Not Permitted |
| GTAW | Silicon Residue Permitted Unless Removal Specified by Drawing Note | ||
| Combined Discontinuities | -- | Total Maximum Combined Length of All Imperfections in a Weld, Expressed as a Percent of Total Weld Length | 15% |
| (No Single Type of Imperfection Can Exceed the Limits for That Single Type of Imperfection) | -- |
Procedure to Lengthen the Rock Ejectors
- Use an appropriate lifting device and remove the ejector assemblies from the truck body. The approximate weight of the ejector assembly is 60 kg (132 lb).
- In order to lengthen ejector assembly (A) a section will need to be removed from one end and extended with a new section of steel.
Note: The ball end of ejector assembly (A) is hardened steel. The end with the mounting hole is normal strength structural steel. Therefore, the end with the mounting hole will be the end in which modification and welding will occur. Do not modify the ball end of the ejector assembly.
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| Illustration 3 | g03741496 |
(A) Ejector assembly (AA) 1250 mm (49.20 inch) | |
- Measure 100 mm (3.95 inch) from the end of ejector assembly (A) and scribe a line.
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| Illustration 4 | g03741520 |
(A) Ejector assembly (BB) 100 mm (3.95 inch) | |
- Cut along the scribed line in order to remove the end of ejector assembly (A) with the mounting hole.
- For the 785 trucks fabricate a new plate from ASTM A36 material according to the dimensions shown in Illustration 5.
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| Illustration 5 | g03741538 |
Fabricated plate (B) for the 785 (B) Fabricated plate (CC) 114 mm (4.49 inch) (DD) 57 mm (2.24 inch) (EE) 45 mm (1.77 inch) (FF) 1352 mm (53.23 inch) (GG) 40 mm (1.57 inch) (HH) 50 mm (2.00 inch) | |
- For the 789 trucks fabricate a new plate from ASTM A36 material according to the dimensions shown in Illustration 6.
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| Illustration 6 | g03741624 |
Fabricated plate (B) for the 789 (B) Fabricated plate (JJ) 114 mm (4.49 inch) (KK) 57 mm (2.24 inch) (LL) 45 mm (1.77 inch) (MM) 1465 mm (57.68 inch) (NN) 40 mm (1.57 inch) (PP) 50 mm (2.00 inch) | |
- Prepare the cut end of ejector assembly (A) for welding to the free end (opposite of hole end) of the new fabricated plate.
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| Illustration 7 | g03741637 |
Preparation of ejector assembly (A) (A) Ejector assembly (RR) 50 mm (2.00 inch) (SS) 20 mm (0.80 inch) (TT) 10 mm (0.40 inch) | |
- Fit prepared end of ejector assembly (A) to new fabricated plate (B) and secure with small tack welds.
Note: A mild preheat of 65° C (150° F) is recommended.
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| Illustration 8 | g03741667 |
(A) Ejector assembly (B) Fabricated plate | |
- Attach run on and run off tabs as shown in Illustration 9.
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| Illustration 9 | g03741674 |
Run on/run off examples | |
- Use a balanced welding technique to minimize distortion. Alternate back and forth between sides until the specified weld sizes are achieved as shown in Illustration 10.
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| Illustration 10 | g03741680 |
Weld details | |
- Illustration 11 depicts the intent of the completed welds. Illustration 12 depicts the weld surface profile sanded flush.
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| Illustration 11 | g03741707 |
View of completed welds | |
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| Illustration 12 | g03741711 |
View of weld surface profile sanded flush | |
- Remove run on and run off tabs and sand to the plate profile.
- Visually inspect all welds in accordance with the acceptance criteria.
- Blend sand all weld starts/stops.
- Use an appropriate lifting device and install the ejector assemblies to the truck body. The approximate weight of the ejector assembly is 120 kg (265 lb).