Applicable Systems
CX210 Excavator
Symptoms
Boom lower function jerky; other functions smooth.
Possible Causes
- Boom lower spool in control valve sticking.
- Boom lower port relief valve unstable (chattering).
- Boom cylinder rod seal bypassing on rod side.
Troubleshooting Steps
- Step 1: Manually actuate boom lower spool with service tool; feel for binding.
Spool moves freely with light finger pressure; no grit. - Step 2: Measure boom lower relief valve cracking pressure.
Cracking pressure 28 MPa ± 0.7 MPa; no chatter. - Step 3: Check boom cylinder for rod-side leakage during controlled lower.
No oil past gland; rod stays clean.
How to Reset
Replace control valve spool or relief valve; reseal boom cylinder if leaking.
Common Replacement Parts
- Control Valve Spool 1542921C1: Control Valve Spool 1542921C1
- Boom Cylinder Seal Kit 1542922C1: Boom Cylinder Seal Kit 1542922C1
Frequently Asked Questions
- Q: Can dirt cause one function to stick?
Yes, particles lodge in specific lands; clean oil prevents this.
- Q: What filter rating for CX210?
10 μm absolute on return line; check every 500 hours.
Source: Case CX210 Hydraulic Manual
Category: Heavy Equipment