Undercarriage of CASE CX800/CX800B Track Roller Assy LH1575/Heavy duty excavator crawler chassis components manufacture

The track roller assembly is a critical component of the excavator’s undercarriage, responsible for supporting the machine’s immense weight and guiding the track chain. For a large excavator like the CX800 (approx. 80 tons), these components are built to extreme specifications.

1. Overview of the Track Roller Assembly

On a CX800, the track roller assembly isn’t a single part but a system of components that work together. The main assemblies you’ll deal with are:

• Track Rollers (Bottom Rollers): These are the primary weight-bearing rollers that ride on the inside of the track chain links. Each side of the machine has multiple rollers.
• Idler Wheels (Front Idlers): Located at the front of the track frame, they guide the track and often provide adjustment for track tension.
• Sprockets (Final Drive Sprockets): Located at the rear, they are driven by the final drive motor and mesh with the track chain links to propel the machine.
• Carrier Rollers (Top Rollers): These rollers guide the top of the track chain and keep it aligned.

For the purpose of this assy (assembly), we will focus on the Track Roller (Bottom Roller) itself.

2. Key Specifications & Part Numbers (Reference)

Disclaimer: Part numbers can change and vary by machine serial number and region. Always confirm the correct part number with your official CASE dealer using your specific machine serial number.

A typical part number for a CX800 Track Roller Assembly might look something like this:

• CASE Part Number: LH1575 (This is a common example for a complete roller assembly. Earlier models might use 6511006 or similar series numbers).
• OEM Equivalent (e.g., Berco): Berco, a major undercarriage manufacturer, produces equivalents. A Berco part number might be TR250B or a similar designation, but this must be cross-referenced.

The assembly typically includes:

• Roller body
• Two integral flanges
• Seals, bearings, and bushings (pre-assembled)
• Grease fitting

Dimensions (Approximate for a CX800-class machine):

• Overall Diameter: ~250 mm – 270 mm (9.8″ – 10.6″)
• Width: ~150 mm – 170 mm (5.9″ – 6.7″)
• Bore/Bushing ID: ~70 mm – 80 mm (2.75″ – 3.15″)
• Shaft Bolt Size: Typically a very large bolt (e.g., M24x2.0 or larger).

3. Maintenance & Inspection

Regular inspection of the track rollers is essential to prevent costly damage to the entire undercarriage.

1. Flange Wear: Measure the flange width. Compare it to the width of a new roller. Significant wear (e.g., over 30% reduction) means the roller can no longer properly guide the track chain, leading to derailment risk.
2. Seal Failure: Look for signs of grease leaking out or dirt entering the roller. A failed seal will lead to rapid bearing failure. A dry, rusty appearance around the hub is a bad sign.
3. Rotation: The roller should turn freely but without excessive wobble or grinding. A seized roller will cause rapid wear on the track chain link.
4. Wear Pattern: Uneven wear on the roller’s tread can indicate other undercarriage issues (misalignment, improper tension).

Recommended Interval: Inspect undercarriage components every 10 operating hours for severe applications (abrasive conditions), or every 50 hours for normal service.

4. Replacement Guidance

Replacing a track roller on an 80-ton excavator is a major job requiring proper equipment and safety procedures.

Tools & Equipment Needed:

• High-capacity jack and solid cribbing blocks.
• Hydraulic jackhammer or torch for removing seized bolts.
• Extremely large sockets and impact wrenches (e.g., 1-1/2″ or larger drive).
• Lifting device (crane or excavator bucket) to handle the heavy roller.
• Personal Protective Equipment (PPE): Steel-toed boots, gloves, eye protection.

General Procedure:

1. Block the Machine: Park the excavator on solid, level ground. Lower the attachment to the ground. Block the tracks securely.
2. Relieve Track Tension: Use the grease valve on the track tensioner cylinder to SLOWLY release hydraulic pressure and slacken the track. Warning: Stand clear as high-pressure grease can be released.
3. Support the Track Frame: Place a jack and solid blocks under the track frame near the roller to be replaced.
4. Remove the Bolts: The roller is held on by two or three massive bolts that thread into the track frame. These are often incredibly tight and corroded. Heat (from a torch) and a high-power impact wrench are often necessary.
5. Remove Old Roller: Once the bolts are out, you may need to use a pry bar or puller to break the roller free from its mounting bosses.
6. Install New Roller: Clean the mounting surface. Install the new roller assembly and hand-tighten the new bolts (often included with a new assembly). It is critical to use new high-strength bolts.
7. Torque Bolts: Tighten the bolts to the manufacturer’s specified torque. This will be an extremely high value (e.g., 800-1200 lb-ft / 1100-1600 Nm). Use a calibrated torque wrench.
8. Re-tension Track: Re-pressurize the track tensioner with a grease gun to the correct sag specification (found in the operator’s manual).
9. Check & Lower: Check that everything is secure, remove the jacks and blocks, and perform a final visual inspection.

5. Where to Buy

1. CASE Official Dealer: The best source for guaranteed OEM parts that match your exact serial number. Highest price, but ensures compatibility and warranty.
2. OEM Undercarriage Suppliers: Companies like Berco, ITR, and VMT produce high-quality aftermarket undercarriage components that are often direct replacements for CASE parts. They offer a good balance of quality and price.
3. Aftermarket/Generic Suppliers: Numerous companies produce lower-cost alternatives. Quality can vary significantly. It’s crucial to source from a reputable supplier with positive reviews for large excavators.

Recommendation: For a machine as valuable as a CX800, investing in OEM or top-tier OEM-equivalent parts (like Berco) is often more cost-effective in the long run due to their longer service life and better protection for your entire undercarriage system.