Blog

Top 5 Common Rotary Drilling Rig Failures: Causes and Troubleshooting Methods

In engineering projects, rotary drilling rigs often encounter the following 5 most common failures. Here, we summarise the causes and troubleshooting methods for these issues.

1. Insufficient Torque in Rotary Drilling Rig Powerhead

Failure Symptom:
During drilling operations, the powerhead lacks sufficient torque, with inadequate rotation speed in both forward and reverse directions. Unusual noises are heard from the powerhead motor and gearbox during operation.

Failure Analysis:
Insufficient powerhead torque can be attributed to hydraulic or mechanical issues:

  1. Low hydraulic oil pressure in the system.

  2. Powerhead motor failure, gearbox malfunction, or mechanical damage in the gearbox.

Possible Causes:

  1. Insufficient pilot pressure or improperly set relief valve pressure.

  2. Damaged powerhead motor or excessive hydraulic oil leakage.

  3. Worn-out components in the powerhead gearbox.

  4. Mechanical failure in the powerhead gearbox.

Troubleshooting Steps:

  1. Check the main hydraulic system pressure. If normal, the issue is likely mechanical.

  2. During inspection, periodic abnormal noises are detected from the gearbox and motor. Disassemble the motor and inspect the output shaft—no issues found.

  3. Remove and disassemble the gearbox. Ensure a clean workspace and follow the proper disassembly sequence. Inspect internal gears and identify damaged components.

  4. Replace the faulty gear, reassemble the gearbox and motor, and restore the rig. Normal operation resumes.

Key Takeaway:
Mechanical damage in the powerhead gearbox reduces torque output and causes unusual noises. Early detection prevents further damage.

2. Rope Press Malfunction in Rotary Drilling Rig

Failure Symptom:
The rope press gets stuck and fails to rotate, causing severe wire rope wear.

Failure Analysis:
A stuck rope press and excessive wire rope wear are typically due to inadequate lubrication, deformation, or internal bearing failure.

Possible Causes:

  1. Insufficient lubricating grease inside the rope press.

  2. Deformation of the rope press.

  3. Damaged internal bearings are causing jamming.

Troubleshooting Steps:

  1. Inspect the rope press—no deformation, but surface wear is evident.

  2. Disassemble and confirm the lack of lubrication.

  3. Further inspection reveals damaged internal bearings.

  4. Replace bearings, reassemble, and lubricate properly to resolve the issue.

3. Mast Cylinder Oil Leakage and Non-Vertical Mast

Failure Symptom:
Oil leakage from the mast cylinder, and the mast does not remain vertical.

Failure Analysis:
Possible causes include a broken piston rod head, damaged oil seals, or internal leakage in the balance valve.

Possible Causes:

  1. Cracked mast piston joint.

  2. Damaged mast cylinder oil seals.

  3. Internal leakage in the balance valve.

Troubleshooting Steps:

  1. Inspect the cylinder piston joint for cracks and surface defects.

  2. Open the cylinder and find damaged seals and O-rings.

  3. Replace seals, O-rings, and gaskets, then reassemble. Test for leaks—normal operation resumes.

Key Takeaway:
Improper operation can cause wire rope contact with the piston rod, leading to surface damage and oil leaks. Prompt repairs prevent further issues.

4. Mast Tilting During Erection/Lowering

Failure Symptom:
The mast tilts during erection or lowering, with unsynchronised mast cylinders.

Failure Analysis:
Possible causes include inconsistent electro-proportional valve opening, balance valve failure, or internal cylinder leakage.

Possible Causes:

  1. Uneven electro-proportional valve current settings.

  2. Balance valve malfunction.

  3. Damaged cylinder seals are causing internal leakage.

Troubleshooting Steps:

  1. Adjust the valve current (950ma/850ma)—no improvement.

  2. Clean and inspect the balance valve—no jamming.

  3. Disassemble the cylinder and find damaged seals. Replace seals—issue resolved.

Key Takeaway:
Check electrical settings, hydraulic circuits, balance valves, and cylinder seals systematically.

5. Rotation Jitter in Rotary Drilling Rig

Failure Symptom:
Severe rotation jitter at low engine speed (1st gear), with pressure fluctuations in Pump 1.

Failure Analysis:
Possible causes include unstable pilot pressure, faulty rotation relay, damaged rotation motor, or main pump failure.

Possible Causes:

  1. Pilot circuit malfunction.

  2. Unstable rotation relay.

  3. Damaged rotation motor.

  4. Faulty main pump.

Troubleshooting Steps:

  1. Check pilot pressure—normal and stable.

  2. Rule out motor failure since other functions also show pressure fluctuations.

  3. Confirm main pump and pilot pump failure. Replace both—normal operation resumes.

Key Takeaway:
Pressure fluctuations indicate pump failure. Replacing the main and pilot pumps resolves the issue.

Conclusion

Understanding these common rotary drilling rig failures helps in timely diagnosis and repair, minimising downtime and preventing major damage. Regular maintenance and prompt troubleshooting ensure optimal rig performance.

Recent Posts