| NOTICE |
|---|
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on Caterpillar products. Dispose of all fluids according to local regulations and mandates. |
Boom Chains
The boom extension chain and the chain that retracts the boom must be cleaned and inspected. Also, the chains must be measured for wear. The chains must be lubricated after two years or every 3000 hours. In severe operating conditions, this service interval must be reduced.
Disassemble the chains from the boom. For disassembly and assembly procedures for the chains, refer to Disassembly and Assembly, RENR3437.
Cleaning and Inspection
Use a suitable degreaser to thoroughly clean the chains. Remove all traces of dirt and grease and lay the chains on a clean bench for inspection.
Carefully inspect the full length of the chains for damage, and in particular check for the following possible damage:
- Cracked link plate or missing link plates
- Elongated holes in link plate
- Loose pins
- Pins with damaged heads
- Rust or corrosion on link plates
Mark the most noticeable worn section of each chain. This will usually be near the center of the chain.
Measuring Chain Wear (Boom Extend)
Nominal pitch equals 25.4 mm (1 inch).
Nominal height of the plate equals 24 mm (.944 inch).
- Apply a load of 3.19 kN (717 lb) to the end of the chain in order to take up all clearance and wear.
- Measure the dimension (B) between the 16 pin centers of the most worn section of the chain. This is equal to 15 pitches with a nominal length of 381 mm (15 inch). If the measurement shows an elongation of more than 2% or the measurement is greater than 388.6 mm (15.30 inch) the chain must be replaced.
 | |
| Illustration 1 | g00747739 |
Measuring Points for Chains (Boom Extend/Retract) | |
- Measure the dimension (A) on all of the inner plates and on all of the outer plates between the same pin centers. If any measurement shows more than 5% wear or the measurement is less than 22.8 mm (0.897 inch) the chain must be replaced.
Measuring Chain Wear (Boom Retract)
Nominal pitch equals 19.5 mm (.750 inch).
Nominal height of the plate equals 18 mm (.708 inch).
- Apply a load of 1.42 kN (319 lb) to the end of the chain in order to take up all clearance and wear.
- Measure the dimension (B) between the 21 pin centers of the most worn section of the chain. This is equal to 20 pitches with a nominal length of 381 mm (15 inch). If the measurement shows an elongation of more than 2% or the measurement is greater than 388.6 mm (15.30 inch) the chain must be replaced.
- Measure the dimension (A) on all of the inner plates and on all of the outer plates between the same pin centers. If any measurement shows more than 5% wear or the measurement is less than 17.1 mm (0.673 inch) the chain must be replaced.
Note: If only one chain is outside the tolerance for wear, it is not necessary to replace both of the chains in the set. If the boom is disassembled because of breakage to the chains both chains must be replaced.
Note: When you measure chain wear the loads that are applied to the chains are equal to 1% of the minimum load that will break the chains.
Lubrication
Spray the full length of each chain on both sides with 1U-8266 Chain and Cable Lubricant. Ensure that the lubricant penetrates the working surfaces between the links and pins by articulating the chain as the spray is applied.
When the chains are assembled into the boom, lubricate the pins at the anchor points.
Ensure that the proper precautions are taken when you use pressurized containers and solvents. Also, use the proper protective equipment and clothing when you use pressurized containers and solvents.