A Comprehensive Guide to Gyratory Crusher Main Shaft Sinkage: Diagnosis and the Jacking Repair Process

This document provides a systematic examination of main shaft sinkage in gyratory crushers, a critical mechanical failure. It details the underlying causes of this condition, outlines a sequential diagnostic protocol for field investigation, and explicates the standardized hydraulic jacking procedure for restoration. The guide emphasizes the importance of recognizing early warning signs, applying precise measurement techniques, and executing a safe realignment to recover core geometrical tolerances. Implementing the subsequent preventive strategies is fundamental for ensuring operational continuity and mitigating the risk of prolonged, costly downtime. Understanding the function of the gyratory crusher is the first step in comprehending the severity of this failure mode.

Understanding Main Shaft Sinkage in Gyratory Crushers

Main shaft sinkage represents a significant deviation from the crusher's engineered operating geometry. It is not a minor shift but a definitive indicator of advanced wear or damage within several key internal assemblies. This condition necessitates immediate technical attention to prevent a cascade of secondary failures that can compromise the entire crushing system. The financial and operational impacts of unaddressed sinkage escalate rapidly, transforming a component repair into a major structural overhaul. The integrity of the entire crushing chamber depends on maintaining precise component alignment.

The phenomenon is defined as the abnormal axial downward displacement of the crusher's main shaft and the attached mantle from their designated position. This displacement directly alters the critical parallel zone between the mantle and the concave liners. The geometry of this crushing chamber is precisely designed to achieve target product specifications; any alteration disrupts the applied compressive forces and the trajectory of material flow. Consequently, the control over the final discharge size is lost, leading to inconsistent and often oversized product output.

Definition and Mechanical Implications of Sinkage

At its core, sinkage is a positional failure of the main shaft assembly. The shaft is designed to rotate within a specific vertical envelope, supported by a combination of bearing surfaces. When these supports wear beyond allowable limits, the entire assembly settles. This settling reduces the effective operational height of the crushing chamber. The immediate consequence is an unintended and uncontrollable increase in the crusher's closed-side setting, which is the minimum gap between the mantle and concave at the discharge point.

The change in chamber geometry redistributes crushing pressures unevenly across the liner surfaces. Areas not designed for high stress experience increased load, accelerating wear in localized patterns. This leads to premature liner failure, often requiring replacement long before the liner's theoretical service life is reached. Furthermore, the eccentric motion of the shaft may become constrained or irregular, introducing abnormal vibrations and cyclical loading into the main frame and foundation.

Direct Operational Consequences and Hazards

The primary operational hazard of shaft sinkage is the loss of product size control. A crusher's setting is its fundamental control parameter for gradation. With sinkage, the setting widens uncontrollably, allowing larger rocks to pass through the chamber unbroken. This results in a product stream that fails to meet specification, potentially shutting down downstream processes or requiring reprocessing. The power draw of the crusher may also become erratic, spiking as the chamber geometry causes rock-on-rock nipping in undesirable locations.

Beyond product quality, the mechanical integrity of the crusher is jeopardized. Abnormal vibrations transmitted through the structure can fatigue welds, loosen mechanical fasteners, and damage ancillary equipment. In severe cases, the misaligned loading can induce stress cracks in the cast main frame or the main shaft itself. The resulting repair is no longer a component swap but a major, time-intensive rebuild of the crusher's core structure, involving complex welding, machining, and realignment.

Criticality of Timely Intervention and Response

Addressing main shaft sinkage at the earliest possible stage is an economic imperative. The rate of component wear is not linear; it accelerates as geometry degrades. Initial wear on the thrust bearing may cause a millimeter of sinkage. This small shift, however, misaligns the main shaft sleeve within the eccentric bushing, creating edge loading and causing rapid, exponential wear of the much larger and more expensive bronze bushing surfaces.

Delaying intervention allows a single-point failure to propagate into a multi-component system failure. What begins as a worn thrust washer can escalate into scored main shaft sleeves, galling of the eccentric bushing, and even seizure or catastrophic failure of the bottom bushing assembly. Each additional damaged component increases the repair cost, the required parts inventory, and, most critically, the machine downtime. Proactive identification and correction are therefore central to maintaining asset reliability and plant throughput.

Common Underlying Causes and Initiating Factors

Several interrelated factors typically converge to cause main shaft sinkage. The most prevalent root cause is the excessive wear of the thrust bearing assembly. This assembly, comprising hardened washers and a seating ring, carries the entire axial load of the main shaft and mantle. Continuous operation under high load gradually wears down these surfaces, allowing the shaft to descend. Wear rates are heavily influenced by lubrication quality and the presence of abrasive contaminants in the oil film.

Other contributing causes include the gradual wear of the main shaft sleeve and the matching eccentric inner bushing, increasing their running clearance. While this wear primarily affects crusher performance and power draw, significant clearance can influence shaft positioning. Historical traumatic events, such as an uncrushable object like tramp metal or an extreme overload event, can also impart impact forces that deform bearing surfaces or momentarily exceed the material yield strength, creating a permanent set that manifests as sinkage.

Systematic Diagnostic Procedure for Identifying Sinkage

A methodical diagnostic approach is essential to confirm sinkage, quantify its magnitude, and isolate the primary causative factors before any repair is attempted. This procedure moves from external observations and operational data review to internal inspection and precise measurement. Adhering to a structured sequence ensures no critical evidence is overlooked and that the repair plan accurately addresses all contributing issues, thereby preventing premature reoccurrence of the failure.

The diagnostic process begins while the crusher is still operational, leveraging data already available to maintenance personnel. It then progresses through a safe shutdown and lock-out, followed by external checks, and culminates in the internal inspection of core components. Each phase builds upon the findings of the previous one, creating a comprehensive picture of the crusher's internal condition. This systematic approach transforms a complex problem into a series of manageable, verifiable tasks. Accurate diagnosis is as crucial as the repair itself for mining and quarrying operations that depend on crusher availability.

Initial Symptom Gathering and Operational Data Review

The diagnostic process initiates with a review of the crusher's recent operational history. Operators and process engineers should be consulted regarding any anomalous behavior observed in the preceding weeks or months. Key indicators include a noticeable and persistent coarsening of the product output despite no change to the crusher's control setting. Fluctuations in the crusher's amperage or power draw, especially unexplained peaks, can signal binding or irregular loading due to altered chamber geometry.

Audible clues are also significant. The development of new or intensified rhythmic knocking, grinding, or scraping sounds from the crushing chamber often precedes measurable sinkage. Maintenance logs should be examined for a history of frequent tramp metal events or uncrushable material entering the crusher, as these incidents deliver shock loads that can initiate bearing damage. This retrospective analysis provides contextual clues that guide the subsequent physical inspection.

External Inspection and Preliminary Measurement Post-Shutdown

Following a safe and complete equipment shutdown and isolation, the first physical inspection begins. A thorough external visual check is conducted for signs of oil leakage, particularly around the base of the main frame and the hydraulic support system. The initial and most direct evidence of sinkage is obtained by measuring the current closed-side setting at the discharge point using manual gauges or a lead slug method. This measured value is compared directly to the crusher's last known calibrated setting.

A discrepancy where the measured setting is consistently larger than the intended setting provides strong preliminary confirmation of sinkage. Additionally, the physical condition of the main frame and its foundation should be inspected for any cracks or signs of movement. Any accumulated debris or metal particles around the base of the crusher should be noted and potentially sampled, as they may offer clues about the nature of internal wear.

Lubrication System and Filtration Unit Examination

The crusher's lubrication system plays a critical role in preventing wear and must be thoroughly evaluated. A representative oil sample should be drawn from the main circulation line and submitted for laboratory analysis. The analysis typically checks for viscosity breakdown, increased acidity, and most importantly, the presence and concentration of wear metals. Elevated levels of bronze or copper particles strongly indicate accelerated wear of the eccentric bushing or bottom bushing, which are often made from these materials.

Concurrently, the system's filtration units must be inspected. The condition of the used filter elements can be very informative. A filter heavily laden with fine bronze powder suggests ongoing bushing wear. The system's pressure differential gauges should be checked against historical readings; a rising pressure drop across filters can indicate a high contaminant load. Ensuring the lubrication system is functioning correctly is a prerequisite before any internal inspection proceeds.

Preparation for Internal Inspection of Critical Components

To conclusively identify the root cause, direct visual and measured inspection of internal components is mandatory. This requires safe disassembly. The procedure begins with the removal of the upper frame section, often called the top shell. This major component houses the concave liners and must be carefully lifted away using an overhead crane. Following this, the entire mantle and main shaft assembly can be extracted.

This extraction reveals the internal chamber, allowing access to the eccentric assembly, the thrust bearing housing, and the lower main shaft area. Prior to disassembly, all necessary lifting equipment, rigging, and support tools must be prepared and certified. This phase of the diagnosis is equipment-intensive and requires meticulous planning to avoid damage to components and ensure personnel safety.

Identifying Root Causes: Inspection of Core Wear Components

With the crusher disassembled, the focus shifts to a detailed examination of the specific components whose failure directly leads to sinkage. This stage involves precise dimensional measurements and visual assessment against manufacturer specifications. The goal is not only to confirm which parts are worn but to quantify the extent of wear, thereby determining the exact corrective action required for each element. This granular analysis informs the parts replacement list and the calculation for the subsequent jacking procedure.

Each component interacts within a tightly toleranced system. Wear in one area often precipitates or exacerbates wear in another. Therefore, inspection must be holistic, examining all related interfaces. The primary suspects are the thrust bearing assembly, the main shaft sleeve and eccentric bushing interface, the bottom bushing area, and the main shaft itself. Documenting findings with photographs and detailed measurement records is essential for analysis and future reference. The main shaft is the central component whose position must be restored.

Examination of the Thrust Bearing Assembly

The thrust bearing assembly is the primary component responsible for supporting the vertical load of the main shaft. It typically consists of a series of large-diameter, hardened steel washers and a bronze or bronze-faced housing. Inspection involves a thorough cleaning of all parts to remove grease and debris. Each washer and the seating surface in the housing must be visually examined for signs of pitting, scoring, galling, or uneven wear patterns.

The most critical measurement is the wear depth on the thrust washers. This is performed using precision height gauges or depth micrometers across multiple radial points. Manufacturers specify a maximum allowable wear depth, often in the range of 6 to 10 millimeters for large crushers. Exceeding this limit directly translates into an equivalent amount of main shaft sinkage. The flatness of the washers and the housing must also be checked, as warping can cause uneven load distribution and accelerated failure.

Clearance Measurement Between Main Shaft Sleeve and Eccentric

The interface between the main shaft sleeve and the eccentric inner bushing is a critical wear point that influences crushing performance and shaft stability. Excessive clearance here does not directly cause sinkage but is a common concurrent issue that must be addressed during repair. Measurement requires specialized tools, including large inside micrometers and outside micrometers or calibrated snap gauges.

The inside diameter of the eccentric bushing is measured at several vertical and circumferential positions to check for ovality and taper. The outside diameter of the main shaft sleeve is similarly measured. The difference between these measurements establishes the radial running clearance. This clearance is compared to the manufacturer's recommended new clearance and maximum allowable service clearance. Clearances exceeding 150% to 200% of the original specification usually necessitate replacement of one or both components to restore proper crushing ratio and efficiency.

Inspection of the Bottom Bushing and Hydraulic Piston Area

The bottom of the main shaft is supported by a bushing or directly interfaces with a hydraulic piston system in modern crushers. This area must be inspected for wear or damage that could contribute to instability. The bottom bushing, if present, is examined for scoring, seizure marks, or excessive wear that could allow lateral movement of the shaft tip. The sealing surfaces for the hydraulic system are checked for leaks or damage.

For crushers with a hydraulic support piston, the piston's crown and its contact area on the bottom of the main shaft are critical. These surfaces must be perfectly clean, smooth, and free of any pitting or deformation. Any imperfection here can create a point load, leading to uneven stress and potential for further damage. The functionality of the hydraulic system itself, including pressure holding capability, should be verified as part of the overall assessment.

Potential Damage Assessment of the Main Shaft Body

The main shaft itself is a massive, costly forging and must be meticulously inspected for any signs of permanent damage. The areas of highest concern are the tapered fit where the mantle is mounted, the sealing surfaces, the journals that contact the bushings, and the thrust bearing seat. A visual inspection is conducted first, looking for cracks, deep scratches, or corrosion pits. Dye penetrant or magnetic particle inspection methods are often employed to detect surface-breaking cracks that are not visible to the naked eye.

The dimensional integrity of the shaft is also verified. Key diameters and the taper are measured to ensure they are within original tolerances. Any evidence of bending or twisting is a serious condition. The thrust bearing seat, a critical horizontal shoulder, must be checked for flatness and parallelism. Any damage to the main shaft body may require specialized in-situ machining or, in worst-case scenarios, complete shaft replacement, which is a major capital expense.

The Hydraulic Jacking Repair Method: Preparation and Procedure

The hydraulic jacking process is the definitive corrective action for restoring a sunk main shaft to its correct operational height. This procedure involves the controlled application of force to lift the massive shaft assembly, allowing for the installation of new thrust bearing components or adjustment shims. Safety and precision are paramount, as the forces involved are enormous and miscalculation can lead to equipment damage or personal injury. A successful jacking operation requires detailed planning, the correct equipment, and strict adherence to a step-by-step protocol.

Before any force is applied, a comprehensive work plan must be developed. This plan identifies the specific jacking points on the crusher frame, calculates the required lifting force and stroke, and selects appropriately rated hydraulic jacks and pumps. All equipment, including jacks, hoses, pressure gauges, and load-spreading plates, must be inspected and certified. Personnel must be fully briefed on their roles, communication signals, and emergency procedures. The area around the crusher must be secured to prevent unauthorized access during the operation. The principles of controlled force application are also found in modern single-cylinder hydraulic cone crushers.

Safety Protocols and Pre-Repair Tool Preparation

Establishing a rigorous safety protocol is the non-negotiable foundation of the jacking repair. The crusher must be mechanically locked out and tagged out from all energy sources. The foundation and main frame are visually and audibly inspected for any cracks or weaknesses that could compromise stability under load. The required tooling extends beyond hydraulic jacks to include high-capacity lifting equipment for handling heavy components, precision dial indicators for measurement, and a variety of machined steel shims and packing plates.

Communication is a critical safety element. A single person should be designated as the jacking operation supervisor, with all other personnel following clear, pre-arranged verbal or hand signals. Hydraulic hoses and connections are pressure-tested away from the work area before being installed. Backup mechanical support, such as steel blocking or custom-built support stands, is prepared and staged nearby to secure the shaft immediately once the target height is achieved, providing a fail-safe in case of hydraulic system failure.

Installation of Jacking Equipment and Measurement Instruments

Hydraulic jacks are strategically positioned at designed jacking points on the crusher's lower frame. These points are engineered to handle the concentrated loads without deformation. Load-spreading plates made of thick steel are placed between the jack rams and the frame to distribute the force evenly. Multiple jacks may be used in parallel, and they must be connected to a common hydraulic pump system with a central control valve to ensure synchronous lifting.

Simultaneously, measurement instruments are installed to monitor the lift with extreme accuracy. Several dial indicators, with a precision of at least 0.01 millimeters, are mounted on fixed reference points around the crusher frame. Their probes contact clean, machined surfaces on the main shaft or a fixture attached to it. These indicators provide real-time feedback on the vertical displacement of the shaft at multiple points, ensuring it is lifted evenly without tilting or binding.

Phased Pressurization and Continuous Real-Time Monitoring

The actual lifting begins with the gradual and controlled pressurization of the hydraulic jacks. Pressure is increased in small, deliberate increments, often pausing to allow the structure to settle and stabilize. The operator observes the pressure gauges and the readings from all dial indicators simultaneously. The goal is a smooth, uniform ascent indicated by all dials moving at nearly identical rates. Any significant discrepancy between indicator readings signals that the shaft is beginning to tilt or bind, requiring an immediate pause and corrective adjustment of jack pressures.

This phase is characterized by extreme caution. The load on the jacks is immense, often reaching hundreds of tons. Operators listen for any unusual sounds such as creaking or popping from the frame. The travel of each jack ram is monitored to ensure no jack is reaching its stroke limit prematurely. The process is slow, sometimes taking hours to lift the shaft only a few centimeters, as the priority is control over speed.

Achieving Target Height and Implementing Temporary Locking

The jacking continues until the dial indicators confirm the main shaft has been lifted to a height slightly above its theoretical correct position. This extra height, typically a few millimeters, is essential to create the necessary clearance for installing new thrust bearing washers and any required adjustment shims. Once the target height is reached and stabilized, the hydraulic pressure is locked in to hold the position.

Immediately, the pre-prepared mechanical locking devices are put into place. These are substantial steel blocks or custom-fitted supports inserted into the space between a solid portion of the main shaft and a strong point on the crusher frame. They are carefully driven or adjusted to take the load off the hydraulic jacks, providing a purely mechanical and fail-safe support for the shaft. Only after this mechanical lock is verified as secure is hydraulic pressure slowly and carefully released, transferring the entire load of the shaft to the temporary supports.

Installation of Adjustment Shims and Final Dimensional Verification

With the main shaft securely held at the elevated position, the work area around the thrust bearing seat becomes accessible. The old, worn thrust washers are removed. The exact thickness of the new thrust bearing assembly is known. The vertical distance the shaft was lifted is precisely known from the dial indicator records. The thickness of the shim pack required to fill the remaining gap and set the final shaft height is calculated from this data.

The new thrust washers and the calculated shim pack are meticulously cleaned and installed on the thrust bearing seat. All components must lie perfectly flat and flush. Following installation, the mechanical locking supports are carefully removed, allowing the full weight of the main shaft assembly to be gradually lowered onto the new bearing surface. Final dial indicator measurements confirm that the shaft settles at the exact designed height. This precise restoration of geometry is critical for proper feed size acceptance and chamber function.

Post-Repair Verification, Reassembly, and Commissioning Protocol

Successful jacking and installation of new components mark a major milestone, but the repair is not complete until the crusher is fully reassembled, verified, and returned to stable operation. This phase requires the same level of discipline as the disassembly and repair. A systematic approach to reassembly, lubrication, and step-wise commissioning ensures that no new issues are introduced and that the repair delivers its intended long-term performance. Rushing this final stage can compromise the entire previous effort.

The process involves a series of checks and tests, each serving as a quality gate before proceeding to the next. It begins with final geometric checks before major components are reinstalled, progresses through a meticulous cleaning and flushing of the lubrication system, and culminates in a controlled, monitored run-in period. Documentation throughout this phase is crucial, as it establishes a new performance baseline for the equipment and provides valuable data for future maintenance planning. Effective reassembly ensures the longevity of both the concave and mantle liners.

Final Geometric Validation of Shaft Position and Discharge Setting

Before reinstalling the upper frame and mantle, a final verification of the main shaft's restored height is performed using the same precision measurement tools employed during jacking. This confirms that the shaft settled correctly onto the new bearing surfaces. Following this, the mantle is installed onto the main shaft taper, ensuring a clean, dry fit for maximum holding power. The upper frame, containing the new or rotated concave liners, is then lowered into position and bolted securely to the main frame.

With the crushing chamber fully assembled but empty, the crusher's drive system is engaged briefly to rotate the main shaft slowly for several complete revolutions. This "barring" or "turning" check ensures there is no binding or interference within the newly aligned internal components. Finally, the closed-side setting at the discharge point is manually measured at multiple points around the circumference of the chamber. These measurements must be consistent and match the target setting within a tight tolerance, confirming that the chamber geometry has been correctly restored.

Lubrication System Flushing and Refilling Procedure

Following a major repair involving new bushings and bearings, the lubrication system must be purged of any contaminants introduced during the work. This is achieved through a flushing procedure. The system is filled with a low-viscosity flushing oil or a portion of the new service oil. The crusher's lubrication pump is started, and the oil is circulated through the entire system, bypassing the main bearings initially to push debris through the filters. Special attention is given to flushing all auxiliary lines and coolers.

Filters are monitored closely and changed frequently during this process until they show no significant accumulation of particles. After several hours of flushing, the oil is drained completely. The system is then refilled with the correct grade and volume of new, high-quality crusher lubricant. Oil analysis should be performed on a sample of this new oil after a short circulation period to establish a clean baseline for future comparison. Proper lubrication is as vital for a gyratory crusher as it is for a high-speed VSI fine crusher.

Phased Commissioning and Operational Monitoring Plan

The crusher is returned to service using a gradual, phased commissioning plan designed to identify any issues under progressively increasing load. The first phase is a no-load run. The crusher is started and operated empty for a period of one to two hours. During this time, bearing temperatures are monitored closely with infrared thermometers or permanent sensors. Vibration levels are recorded and compared to pre-failure baselines. Any unusual noises are investigated immediately.

Once no-load operation is deemed stable, the second phase begins with a very low feed rate of soft, easy-to-crush material. This "break-in" period allows the new bearing surfaces to seat properly under light load. Over the course of several hours or shifts, the feed rate and material hardness are gradually increased in steps. At each step, temperature, vibration, power draw, and product size are monitored. Only after the crusher operates stably at its full designed capacity for a sustained period is the repair considered fully commissioned.

Documentation of Post-Repair Baseline Data for Archives

A critical final step is the comprehensive documentation of all post-repair measurements and initial operational data. This creates an invaluable historical record for the asset. The documented data should include the final installed shim thicknesses, the verified main shaft height, the closed-side setting measurements at multiple points, and the results of the no-load and initial load-bearing tests including bearing temperatures and vibration spectra.

This information is archived with the equipment's permanent maintenance records. It serves as the new reference point for all future preventive maintenance inspections and performance evaluations. By comparing future measurements against this post-repair baseline, maintenance teams can detect the earliest signs of wear or deviation, enabling truly predictive maintenance and preventing a recurrence of the catastrophic sinkage failure. This data-driven approach is key to optimizing aggregate processing plant reliability.

Long-Term Preventive Maintenance Strategy to Avoid Sinkage

Proactive maintenance is the most cost-effective strategy for managing gyratory crusher reliability and preventing main shaft sinkage. This strategy moves from reactive repair to condition-based and time-based prevention. It involves establishing routine monitoring protocols, analyzing data for trends, and taking corrective action before functional failure occurs. A robust preventive maintenance program is built on regular inspection intervals, advanced monitoring technologies, and a culture of operational discipline, ensuring crusher availability and protecting the substantial capital investment.

The foundation of prevention is understanding that sinkage is a gradual process resulting from predictable wear mechanisms. By monitoring the rate of this wear, replacement of components can be planned during scheduled shutdowns, avoiding unplanned downtime. The strategy encompasses multiple facets: fluid analysis to monitor the internal wear state, physical measurement of critical clearances during maintenance windows, the use of sensor technology for real-time health assessment, and operational controls to minimize abusive conditions. This holistic view treats the crusher as a system, not just a collection of parts.

Establishing a Regular Oil Analysis and Filtration Regime

Regular, scheduled oil analysis is a powerful predictive tool. Oil samples should be taken at consistent intervals, such as every 500 operating hours or monthly, and sent to a laboratory for analysis. The test report tracks key indicators including viscosity, water content, total acid number, and the concentration of specific wear metals like iron, copper, and tin. Rising levels of copper, for example, provide an early warning of eccentric bushing wear long before it affects performance or causes sinkage.

Complementing oil analysis is a strict filtration maintenance schedule. Filter elements should be changed based on pressure differential, not just a calendar schedule. Using high-efficiency filters and maintaining a clean oil sump are fundamental. The goal is to keep the lubricant clean, cool, and within its specified properties. Contaminated or degraded oil is a primary accelerator of wear in all bearing systems, directly contributing to the conditions that lead to sinkage.

Periodic Measurement and Trend Analysis of Critical Clearances

During every planned major maintenance shutdown, specific dimensional checks must be performed. The wear on the thrust bearing washers should be measured and recorded. The radial clearance between the main shaft sleeve and the eccentric bushing should be checked using the same methods as in the diagnostic phase. Other clearances, such as those in the bottom bushing area, should also be assessed according to the manufacturer's maintenance manual.

The power of this practice lies in trend analysis. By plotting each measurement against operating hours since the last repair, maintenance engineers can calculate precise wear rates. This allows for accurate prediction of when a component will reach its condemnation limit. Replacement can then be scheduled for the next available maintenance window, eliminating surprise failures. This data-centric approach transforms maintenance from a guessing game into a predictable, planned activity.

Implementation of Online Monitoring Systems for Early Detection

Modern sensor technology enables continuous, real-time monitoring of crusher health. Key parameters to monitor online include the temperature of the main and bottom bearings, the vibration amplitude and frequency at multiple points on the frame, and the position of the main shaft. Inductive displacement sensors can be installed to detect micron-level changes in the vertical position of the shaft relative to the frame, providing the earliest possible direct warning of incipient sinkage.

These sensors feed data into a plant's distributed control system or a dedicated machinery health monitor. Software algorithms can analyze the data, looking for trends that deviate from established normal baselines. Alarms can be configured to alert personnel to developing issues, such as a gradual rise in bearing temperature or a very slow drift in shaft position. This allows for investigation and intervention during a scheduled stop, potentially preventing a minor issue from developing into a major failure requiring jacking repair.

Operational Training to Standardize Practices and Avoid Overload

Human factors play a significant role in equipment longevity. Operators must be thoroughly trained on proper crusher feeding practices. This includes ensuring a consistent, choke-fed material stream to promote rock-on-rock crushing rather than metal-on-rock wear, and avoiding erratic feed that causes power surges and mechanical shock. The importance of metal detection and tramp iron removal systems must be emphasized, as tramp metal events are a common trigger for bearing damage that can initiate sinkage.

Maintenance personnel should receive specific training on recognizing the early auditory and operational signs of potential problems. Creating a culture where unusual noises or performance changes are reported and investigated immediately is invaluable. Cross-training between operational and maintenance teams fosters a shared understanding of how daily practices impact long-term machinery health. This collective vigilance is the final, and perhaps most important, layer of defense against catastrophic failures like main shaft sinkage.