Common Mistakes When Lubricating Pneumatic Roofbolters

I. Incorrect Oil Selection – The Most Common and Most Harmful

❌ Using hydraulic oil or heavy rock oil instead of No. 30 machine oil: Hydraulic oil has high viscosity and poor atomization, preventing it from entering the motor with the airflow, leading to lubrication failure; heavy rock oil contains many impurities and easily clogs the oil passages.

❌ Using waste engine oil or inferior oil: Waste engine oil contains metal shavings and oxides, which accelerate gear wear and shorten equipment life.

✅ Correct Practice: The oil cup must use No. 30 machine oil (ambient temperature 10℃~35℃) to ensure atomization and lubrication efficiency.

II. Improper Oil Volume Control – Too Little or Too Much is Risky

❌ Insufficient Oil in the Oil Cup: When the oil level is below 1/3, continuous oil supply is impossible, causing the motor to dry-run and overheat, resulting in damage within a short time.

❌ Overfilling the grease cup, leaving no empty cavity: Failure to adhere to the "10% empty cavity" standard will increase pressure, easily causing oil seal damage, oil leakage, and spraying.

❌ Overfilling the propeller or gearbox: Filling the cavity with grease beyond 2/3 results in poor heat dissipation, increased internal pressure, and affects transmission efficiency.

✅ Correct procedure: Fill the grease cup to 1/2 to 2/3 of its height; for the propeller and gearbox, fill to 2/3 of their volume.

III. Unadjusted oil flow or unresolved blockage – Lubrication interruption

❌ Failure to adjust the oil flow to 2–3 ml per minute: Excessive oil flow is wasteful, while insufficient flow results in inadequate lubrication; precise control via the regulating valve is essential.

❌ Continuing operation despite no oil mist: No oil mist discharge from the muffler indicates a blocked oil circuit or an empty grease cup; forcing operation under these conditions will quickly burn out the motor.

✅ Correct Practice: Check the oil circuit for blockage before starting each shift. Observe the oil mist status during operation; immediately stop the machine if any abnormality is found.

IV. Lubrication Leaks in Critical Components – Neglecting Drill Rods and Sliding Parts

❌ Failure to apply grease before drill rod insertion: This leads to dry friction between the drill rod and drill bushing, causing hexagonal wear, jamming, or even breakage.

❌ Failure to apply anti-rust oil to the outrigger piston rod after each shift: Exposure to a humid environment easily causes rust, resulting in poor extension and retraction of the air leg or damage to the seal.

✅ Correct Practice: Apply lithium-based grease evenly to the hexagonal parts before each drill rod replacement; apply anti-rust oil to the exposed parts of the piston rod after each shift.

V. Poor Maintenance Habits – Lack of Regular Inspection and Cleaning

❌ Failure to clean the oil cup and filter screen for extended periods: Impurities accumulate and clog the oil circuit, affecting oil mist generation.

❌ Adding grease without cleaning the grease fitting: Coal dust and iron filings mix into the reducer, causing abnormal gear wear.

❌ Mixing different types of oil: For example, injecting grease into the oil cup or using calcium-based grease instead of machine oil can cause chemical reactions or blockages.

✅ Correct practice: Establish a pre-shift inspection and post-shift maintenance system to keep all lubrication points clean and the oil pure.

VI. Weak safety awareness – Oilless operation becomes the norm

❌ Forcibly starting the machine despite an empty oil cup: Pneumatic motors rely entirely on oil mist lubrication and cooling; running without oil for 5 minutes can cause gear burnout.

❌ Using wire to tie up leaking oil cups and continuing to use them: This is a serious violation of operating procedures, covering up problems while amplifying risks.