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Common Faults and Troubleshooting Measures for Mine Hoist Gearboxes

2022-07-29

　　I. Damage, Failure, and Troubleshooting of Gears in Mine Hoist Reducers

　　In the gear industry, gear damage and failure can be categorized into six main types: cracks, broken teeth, tooth surface fatigue, tooth surface wear, pitting, and permanent deformation. The damage to gears in mine hoist reducers is no exception.

　　1. Cracks

　　Gear cracks typically occur in areas such as the gear teeth, gear rim, hub, and spokes.

　　Reasons for gear cracks: improper manufacturing processes and formation after operating under overload conditions.

　　Gear crack treatment methods:

　　1) Temporary method: Grind away the metal at the crack to create a smooth, gradual transition around it, and carefully remove the crack to prevent its further propagation.

　　2) Solution: Contact the manufacturer, analyze the cause, and develop a corrective plan to prevent similar incidents from happening again.

　　2. Broken tooth

　　Gear tooth failure types include overload fracture, plastic deformation fracture, and fatigue fracture, among others.

　　Methods to prevent gear tooth breakage:

　　1) Methods to prevent overload breakage: Ensure precise contact during installation, and avoid forcing large, hard objects into the meshing area during use.

　　2) Methods to prevent plastic deformation and breakage: Use periodically with intervals, and replace accessories regularly.

　　3) Methods to prevent fatigue failure: Replace components regularly.

　　II. Damage, Failure, and Troubleshooting of Mine Hoist Reducer Bearings

　　Methods for identifying bearing abnormalities: These can be monitored by tracking conditions such as noise, vibration, temperature, and lubricant status.

　　1. Noise

　　1) Loud metallic noise:

　　Reason 1: Abnormal Load; Countermeasure: Adjust fit, analyze bearing clearance, optimize alignment with the load, and correct the position of the housing shoulder.

　　Reason 2: Improper installation; Countermeasure: Enhance the machining precision of the shaft and housing, and improve both installation accuracy and method.

　　Reason 3: Insufficient or inappropriate lubricant; Solution: Top up the lubricant and choose the right type.

　　Reason 4: Rotating parts are in contact; Countermeasure: Modify the contact area of the curved-path seal.

　　2) Rule-based noise:

　　Reason 1: Rolling surfaces develop indentations, rust, or scratches due to foreign objects; Countermeasure: Replace the bearing, clean the relevant components, improve the sealing mechanism, and use clean lubricant.

　　Reason 2: Surface deformation after steel carburizing; Countermeasure: Replace the bearing and pay attention to its proper usage.

　　Reason 3: Raceway Surface Spalling; Countermeasure: Replace the bearing.

　　3) Irregular Noise:

　　Reason 1: Excessive clearance; Countermeasure: Investigate the fit and bearing clearance, and adjust the preload accordingly.

　　Reason 2: Foreign object intrusion; Countermeasure: Investigate replacing the bearing, clean relevant components, improve the sealing mechanism, and use clean lubricant.

　　2. Vibration

　　Reason: Gear reducer bearings are highly sensitive to vibration damage—issues like spalling, pitting, rusting, cracking, and wear will all manifest in bearing vibration measurements. Countermeasure: By using specialized bearing vibration detectors (such as frequency analyzers), the magnitude of vibrations can be accurately measured, and by analyzing the frequency spectrum, it’s possible to pinpoint the exact nature of any abnormalities.

　　3. Temperature

　　Reasons: Insufficient or excessive lubrication, contaminants in the lubricant, overloading, bearing damage, inadequate clearance, and high friction caused by the oil seal.

　　Countermeasure: At this point, operation must be stopped immediately, and necessary preventive measures should be taken. Installing a thermal sensor allows continuous monitoring of the bearing's operating temperature, enabling automatic alarms or shutdowns if the temperature exceeds safe limits—thus preventing costly bearing failures. Moreover, high temperatures can also harm the bearing’s lubricant. In some cases, excessive bearing heat is directly linked to issues with the lubricant itself. If the bearing operates continuously at temperatures above 125°C for extended periods, its service life will significantly decrease.

　　3. Lubricant Leakage and Handling

　　Reason: Sealing device failure; Countermeasure: Replace the sealing components or improve the lubrication oil circuit (both can be done simultaneously).