Rotary drilling rigs are essential in construction projects, but like any heavy machinery, they can experience failures. Below are the five most common failures, along with their causes and troubleshooting methods to ensure smooth operations.
1. Insufficient Torque in the Rotary Drilling Rig’s Powerhead
Symptoms:
-
The powerhead lacks sufficient torque during drilling.
-
Both forward and reverse rotation speeds are inadequate.
-
Unusual noises from the powerhead motor and gearbox during operation.
Analysis:
The lack of torque can stem from hydraulic or mechanical issues:
-
Hydraulic system: Insufficient hydraulic oil pressure.
-
Mechanical failure: Damaged powerhead motor, gearbox, or transmission.
Possible Causes:
-
Low pilot pressure or improperly set relief valve pressure.
-
Powerhead motor failure or excessive hydraulic oil leakage.
-
Damaged components in the powerhead gearbox.
-
Mechanical failure in the powerhead transmission.
Troubleshooting Steps:
-
Check the hydraulic system’s main pressure. If normal, focus on mechanical issues.
-
Inspect the powerhead motor and output shaft—no issues found.
-
Disassemble the gearbox, ensuring cleanliness and proper disassembly sequence.
-
Identify and replace damaged gears, then reassemble the gearbox and motor.
Key Takeaway:
A faulty gearbox can cause torque loss and unusual noises. Early detection prevents further damage.
2. Rope Press Malfunction (Unable to Rotate)
Symptoms:
-
The rope press is stuck and won’t rotate.
-
Severe wire rope wear.
Analysis:
Lack of lubrication leads to stiffness, deformation, or bearing failure inside the rope press, causing wire rope abrasion.
Possible Causes:
-
Insufficient lubricating grease inside the rope press.
-
Deformation of the rope press.
-
Damaged internal bearings are causing jamming.
Troubleshooting Steps:
-
Inspect the rope press for deformation—only surface wear found.
-
Open the rope press—lack of lubrication detected.
-
Further disassembly reveals damaged bearings.
-
Replace bearings, reassemble, and lubricate properly.
Key Takeaway:
Regular lubrication prevents rope press failures and extends wire rope lifespan.
3. Mast Cylinder Oil Leakage and Non-Vertical Mast
Symptoms:
-
Oil leakage from the mast cylinder.
-
The mast does not remain vertical.
Analysis:
Possible causes include:
-
Broken piston rod head or damaged seals in the mast cylinder.
-
Internal leakage in the cylinder or balance valve failure.
Possible Causes:
-
Cracked mast piston joint.
-
Damaged mast cylinder seals.
-
Internal leakage in the balance valve.
Troubleshooting Steps:
-
Inspect the piston joint—cracks found.
-
Disassemble the cylinder—seals and O-rings are damaged.
-
Replace seals, O-rings, and gaskets, then reassemble.
Key Takeaway:
Damaged seals lead to oil leaks and mast instability. Prevent wire rope contact with the piston rod to avoid damage.
4. Mast Tilting During Erection or Lowering
Symptoms:
-
The mast tilts during erection or lowering.
-
Mast cylinders move out of sync.
Analysis:
Possible causes:
-
Uneven solenoid valve opening.
-
Balance valve malfunction.
-
Internal cylinder leakage due to seal damage.
Troubleshooting Steps:
-
Adjust solenoid valve current—no improvement.
-
Clean and inspect the balance valve—no blockage found.
-
Disassemble the cylinder—damaged seals identified.
-
Replace seals—the mast operates smoothly.
Key Takeaway:
Check electrical, hydraulic, and mechanical components when diagnosing mast synchronisation issues.
5. Rotation Vibration in the Rotary Drilling Rig
Symptoms:
-
Severe rotation vibration at low engine speed.
-
Slight vibration at high speed.
-
Unstable pressure in Pump 1.
Analysis:
Possible causes:
-
Faulty rotation pilot circuit.
-
Unstable rotation relay.
-
Damaged rotation motor or main pump.
Troubleshooting Steps:
-
Check pilot pressure—normal, ruling out relay issues.
-
Test rotation motor—no impact on other functions.
-
Confirm main pump failure—replace the pump and the pilot pump.
Key Takeaway:
Pressure fluctuations indicate pump failure. Prompt replacement restores performance.
