Tuesday, September 21, 2010

Mine Maintenance

1. Introduction
Performing efficient and effective mine maintenance lowers total mining costs, rather than only the costs of the Maintenance Department. The role of mine maintenance is to provide quality work efficiently with minimal disruption to the production routine.

The aim of this chapter is to describe the procedures, personnel, and equipment required to fill this role. The emphasis of the chapter is on Work Practice, including routine maintenance, preventive (and predictive) maintenance, and the provision of adequate shop/warehousing facilities. The Work Practice discussed is specific to the mobile fleet in an underground trackless mine. An appendix (Section 28.7) contains data concerned with mine hoists (lubricants, tools and equipment).

Like the preceding chapters, this one includes rules of thumb and tricks of the trade. While most items are concerned with an underground fleet, some relate to other maintenance tasks and many are generic applying to maintenance in general. Mine Maintenance may be categorized into three principal divisions.
• Management and Administration
• Work Practice
• Operating Environment
Each of these three divisions is subdivided in the main text of this chapter and is dealt with in sequence. Mine Maintenance Department efficiency is typically addressed by directing attention to the following three areas.
• One focus is on minimizing the size of the maintenance work force. The direct cost savings may not be significant; however, the indirect benefits include improved communications, more initiative, and less supervision.
• Another focus is on inventory reduction. Reducing inventory is accomplished directly by component standardization, modular components, repair kits, contract warehousing, and singlesource equipment purchases. Indirectly, inventory reduction is accomplished by employing state-of-the-art diagnostic equipment to displace instinct that results in wrong parts being replaced.
• A third focus is on minimizing the size of the production equipment fleet by increasing its availability and reliability. In this case, cost savings accrue to the production department.

2. Rules of Thumb
General
• The degree of maintenance enforcement at an operating mine should be just less than the point that disruptions to operations are at a level where additional maintenance costs equal the resulting profits from production. Source: David Chick
• In a trackless mine operating round the clock, there should be 0.8 journeyman mechanic or electrician on the payroll for each major unit of mobile equipment in the underground fleet. Source: John Gilbert
• Emergency repairs should not exceed 15% of the maintenance workload. Source: John Rushton
• LHD units at a shallow mine with ramp entry should have a utilization of 5,000 - 6,000 hours per year. Source: Unknown
• Captive LHD units should have a utilization of 3,500 - 4,500 hours per year. Source: Unknown
• LHD units in production service should have a useful life of at least 12,000 hours, including one rebuild at 7,500 hours. A longer life can be presumed from LHD units at the high end of the market with on-board diagnostics. Source: John Gilbert
• Underground haul trucks should have a useful life of 20,000 hours; more if they are electric (trolley system). Source: John Chadwick

Service
• An efficient Maintenance Department should be able to install one dollar worth of parts and materials for less than one dollar of labor cost. Source: John Rushton
• A servicing accuracy of 10% is a reasonable goal. In other words, no unit of equipment should receive the 250-hour service at more than 275 hours. Source: Larry Widdifield

Infrastructure
• With ramp entry, a satellite shop is required when the mean mining depth reaches 200m below surface. A second one is required at a vertical depth of 400m. Source: Jack de la Vergne
• With ramp and shaft entry, a main shop is required underground when the mean mining depth reaches 500m below surface. Source: Jack de la Vergne
• A main shop facility underground should have the capacity to handle 10% of the underground fleet. Source: Keith Vaananen
• Service shops for open pit mines should be designed with plenty of room between service bays for lay-down area. As a rule of thumb, the width of the lay-down between bays should be at least equal to the width of the box of a pit truck. Source: Cass Atkinson

3. Tricks of the Trade
• Whenever figures for equipment availability are considered, they must be accompanied by an explicit definition, otherwise they are worthless. Source: Steve Harapiak
• A guaranteed availability contract with an equipment supplier may be an invitation to replace parts before necessary and pay original equipment manufacturer (OEM) prices for every one. Source: Jack de la Vergne
• To estimate current operating costs for a particular piece of mobile equipment, it is convenient to use monthly charges accumulated over a one-year period. They are kept current by adding the latest month and deleting the 13th month. Source: Robert Winkle
• Checklists developed for routine maintenance intervals typically require a very large number of components be inspected, many quite needlessly. The lists should be audited to identify and eliminate trivial pursuit. Source: Iain Le May
• Inventory can be cut and downtime reduced by providing pre-packaged assortments of springs, O-rings, snap rings, machine screws, springs, and cotter pins. Source: Roger Bryar
• Inventory can be cut and downtime reduced by providing kits (brake, carburetor, valve, O-ring, V-belt, and gasket). Source: Bob Dengler
• Paperwork can be saved and downtime reduced with the implementation of “free-issue” policy where items such as nuts, bolts, and washers are stored in open receptacles outside the warehouse wicket. Source: Earl ‘High Pockets’ Farnham
• Standardization should include both hydraulic fittings and grease fittings. Source: Dave Assinck
• Grease nipples that are difficult to access may be moved to a more convenient location with a pipe extension. Source: Largo Albert
• The permissible wear on a disc brake (for example, 1.3-mm) can be found stamped on the disc near the flange bolt holes. Source: Gerold Heinz
• Brake squeal and creep are caused by glazing of a brake pad surface, which can be quickly corrected with one shot with an out-of-service dry chemical fire extinguisher. Source: Gerold Heinz
• Mechanics should be instructed that when working on a unit of mobile equipment for any reason, the brakes must be checked before releasing the equipment to the operator. Source: Gerold Heinz
• An ultra-sonic bearing cleaner performs well on anti-friction bearings up to 12 inches (300 mm) diameter. Source: Gerard O’Halloran
• Electricians, not mechanics, should grease the bearings on electric motors. Over-lubrication may not be harmful to mechanical equipment, but it is to electric motors. Source: Largo Albert
• A tradesman with rings on his fingers should not be employed in the Maintenance Department. If a mechanic wishes to wear a ring, he should wear it in his left ear. Source: Dave Assinck
• When transporting diesel powered equipment on the highway, the exhaust stack should point to the rear (or be sealed with duct tape), otherwise the turbocharger will be spun in reverse and damaged. Source: Dave Assinck
• Shop facilities should be well lit. The walls and back of underground shops should be routinely whitewashed to avoid becoming darkened with flat textured exhaust soot. Source: John Gilbert
• A small library of equipment operating and spare parts manuals is required in main shop facilities. The library should also include general catalogues for equipment, tools, and supplies, as well as appropriate trade journals. Source: John Gilbert
• Desktop computers in the surface and underground shops should be equipped to display electronic parts catalogues on disk (or CD-Rom) provided by the OEM. Source: John Gilbert
• A plastic wrap over the keyboard of a desktop PC in the shop will protect it from greasy fingers. Source: Red Blanchette
• Concrete aprons installed along the perimeter of a surface shop building will improve housekeeping and facilitate the completion of running repairs that can be performed out of doors. Source: Donald Myntti

4. Management and Administration
Management and Administration is divided into the following four categories.
• Planning and control
• Statistics
• Training
• ISO Accreditation

Planning and Control
A centralized planning and control system is necessary to ensure the planned work of the Maintenance Department will be coordinated with the needs of the mine operators. Without a continuous review, no assurance can be given that work will be organized or completed efficiently. For the system to work effectively, it is necessary to have a dedicated Planning Control Department.

The Planning Control Department has the following primary responsibilities.
• Planning routine maintenance.
• Planning preventive maintenance (PM).
• Coordinating maintenance and repairs.
• Scheduling maintenance and repairs.
• Work loading (allocation of personnel).
• Converting field data to the mine accounting system.

Staff
If the Planning Control Department is dedicated to an equipment fleet, the staff could consist of the following people.
• Supervisor (1) – prepares weekly and monthly plan, reports to Mine Maintenance Superintendent.
• Mechanical Planner (2) – prepares Daily Work Schedule (DWS).
• Electrical Planner (1) – prepares DWS.
• PM Technician (1) – responsible for PM and inventory.
• Technician/Clerk (1) – responsible for inventory.
• Filing Clerk (1) – records.
• Receptionist/Typist (1).
• Expediter (1).
• Translator (1) – (if required at a foreign location).

Track Equipment Repairs and Calculate Statistical Data
Two Planning Control Department tasks are to track equipment repairs and calculate statistical data, such as availability and utilization. The department issues a Monthly Report, including availability, utilization, and detailed costs. Each calendar year, the Planning Department issues an Annual Report summarizing the monthly reports and establishing a proposed schedule for mobile equipment replacement (new purchases). The staff’s primary task is to coordinate input for routine maintenance, routine repairs, rebuilds, etc. Following are the principal implements used to complete this function.
• Numerical identification of equipment
• Equipment roster
• Work order system
• DWS
• Weekly plan
• Monthly report
• Annual report
• Work standards (performance standards)
• Job descriptions

Numerical Identification of Equipment
An identifying number is applied to all equipment by the mine. It is not the serial number. For an equipment fleet, the numbering system starts with No.1 for the first machine purchased and proceeds in chronological order to the latest acquisition.

Equipment Roster
The Equipment Roster is a list of equipment that includes manufacturer, model, date of purchase, location, status, and latest month end hour-meter reading. The list also includes equipment sent away for rebuild, but does not include equipment in the bone yard.

Work Order
A work order (or job ticket) refers to a specific task to be completed on a particular piece of equipment. The Planning and Control Department may initiate a work order for routine maintenance while the Operations Department may initiate a work order for repairs. Once approved, work orders are assimilated into a comprehensive Weekly Plan that is implemented day by day by means of the DWS. The work order and DWS provide the work requested, work instructions, and a record of the work performed.

Daily Work Schedule
The DWS consists of the names and crafts of the journeymen in a particular area of maintenance. The respective columns identify the equipment number, work order number; description, priority of the work, and an estimate of the man-hours to be expended. Subsequent columns list the working hours of the shift and a space for comments.

The DWS system lends itself to computerization, but can be performed manually. Computerization facilitates communications, changes, archiving, and transfers.

Weekly Plan
The weekly plan consists of a list of all mobile equipment scheduled for maintenance during the coming week. The type of maintenance and the standard schedule for each item of work is listed. An allowance is made for emergency repairs. The weekly plan is prepared in advance and provided to the Operations Department, as well as “posted” for planning/information purposes.

Work Standards
Work standards are established by the mine for routine chores and include a list of instructions and expected performance (e.g., eight man-hours for the “100 hour” routine maintenance service). The number of jobs performed in a period of time may be useful; however, the number of man-hours spent on each job determines performance. When work standards are first established, they should be audited to ensure that they are comprehensive and accurate. Loose estimates of man-hours or incomplete instructions must be corrected. The work standards may be expanded to include a bill of materials and special tools required for each job. The standards provide benchmarks for and aid productivity. An example of a work standard appears in the appendix (Section 28.6) along with a list of standard abbreviations useful for computerization.

Job Descriptions
Job descriptions provide working procedures and job classification data. Job description use is not confined to tradesmen and apprentices, but useful for all levels of supervision. Although job descriptions appear to be a logical asset, this management tool is the subject of controversy. Some question whether job descriptions should be employed because of unforeseen problems that may arise. For example, specific job descriptions can impede implementation of cross-training and multitasking programs for tradesmen and invite jurisdictional disputes. Once published, job descriptions can be difficult to delete.

Statistics
As W. Edwards Deming said, “If you can’t measure it, you can’t manage it.” In mine maintenance, efficiency and performance are measured with statistics. Following are the principal statistics employed.
• Equipment availability
• Equipment utilization
• Mine efficiency
• Equipment life cycle
• Manpower utilization
• Work index
• Backlog

Equipment Availability
Equipment availability is the original statistic employed to evaluate equipment performance. Unfortunately, there is not yet an international standard definition of the meaning of this basic measurement. As a result, it is difficult to establish inter-mine benchmark values for fundamental measures of reliability of equipment and maintenance programs. Nevertheless, the measurement is a vital statistic for an individual mine.

Customarily, availability is calculated as the percentage of time the piece of equipment is available to work compared with the total time available. Whenever availability is reported, a definition must accompany the figure, since there are numerous determinations that can be made. A gross time available of seven hours per eight-hour shift (21 hours per mine operating day) may be acceptable, as long as it is clearly defined. Following is the most commonly accepted formula for availability, A.
A = (Tt - Td)/Tt
Where
Tt = total time available in the period of measurement
Td = downtime due to routine maintenance, repairs and lack of replacement parts
It is acceptable (and recommended by at least one authority) that the time a unit of equipment is down for major repairs, overhaul, or rebuild is subtracted from the total available time (Tt) to calculate the figure for availability.

Equipment Utilization
Equipment utilization is another key statistic employed to evaluate mobile equipment performance. Utilization may be expressed in three different ways.
• Hours of service per year
• Tons of ore handled per year
• Percentage of time of productive work compared with the time available to work

Of these three definitions, the first may be the most reliable because it is an absolute value that requires no calculations other than subtraction of hour-meter readings. There is no confusion as to the exact meaning and the resulting figures are not suspect; however, it is acceptable to report three separate values for utilization (for each of the three definitions), if desired.

A utilization of 3,500-4,500 hours per year is typical for a captive unit of underground mobile equipment employed six or seven days per week on a three-shifts per day basis. Higher figures are obtained at shallow mines that can have a “hot seat” operator change on surface.

Mine Efficiency
Mine efficiency is a relatively new term that refers to one aspect of equipment utilization previously described (percentage of time of productive work compared with the total time available to work). When combined with availability, mine efficiency provides a convenient gauge for calculating the production potential of a unit of equipment. Measuring mine efficiency presents a problem. If a unit of equipment were fitted with two hour-meters, one standard and one set not to record engine idle, efficiency could be measured by the difference in readings taken at prescribed intervals. (Once started, production equipment is usually kept running throughout the shift.) Mine efficiency for an open pit may be 85%, but in an underground mine it is only to 60-75% due to complex work access, difficult communication, and shorter muck cycles.

Equipment Life Cycle
The equipment life cycle (useful life of equipment) is a vital statistic that has recently received more attention. For example, the workhorses of an underground fleet are the LHD units, which typically have the shortest life span and receive the most attention. The strength and efficiency of LHD units will quickly deteriorate after 5,000 hours of service if they are not well maintained. A reasonable goal (with a good maintenance program) was once to expect 7,500 hours of reliable service before a major rebuild and a total production life of at least 12,000 hours. Modern LHD units equipped with electronic ignition and on-board diagnostic devices can expect much longer life. After production life, a unit of equipment may be scrapped or customized and put on “light duty” as a utility vehicle.

Manpower Utilization
Manpower utilization (direct utilization of tradesmen) is another one of the fundamental statistics employed to evaluate the effectiveness of mine maintenance. It is often defined as the number of man-hours in a shift that a journeyman mechanic or electrician is actually working on a piece of equipment. The time may average 3 - 3½ hours per shift, which does not include time lost due to travel, waiting (for parts, tools, and equipment), instructions, searching data from manuals, safety huddles, completing forms, timesheets, logs, etc. A low value for this statistic may indicate lack of proper controls, poor organization, scarcity of tools and equipment, and/or inefficient parts and materials delivery to the working areas.

Work Index
Work index is a means to measure sector or overall performance of the Maintenance Department. It is defined as the comparison of labor cost with total cost of maintenance. Work index may be expressed as a ratio, but usually is expressed as a percentage. A par value for the work index is often near 50% and a typical goal is 40%.

Backlog
Backlog is another statistic used to measure performance. The measure of backlog is the estimated number of man-hours required to complete the maintenance and repair work in hand. Historically, it was used to determine when manpower needed to be increased. Backlog can also be an indicator of improvement obtained from a static work force.

Training
For many years, it has been recognized that effective training, education, and development of the mine workforce can only be accomplished with a discrete, formal program requiring specialized staff and an allocated budget.

Dedicated space must be provided and equipped as a training facility (the space can double for safety training and other functions). The facility should be equipped with equipment elements, overhead projectors, flip charts, VCR, and PC with a video data projector. For items of sophistication, such as hydraulic drills or remote LHD operating devices, the manufacturer can usually provide instructors and teaching aids for the particular application. Another valuable asset is a library of video-cassettes (or CD-R) containing training lectures and visual aids (normally obtained from relevant equipment suppliers).

Any training program should be periodically audited for effectiveness to reveal issues requiring attention. An example is finding that there is a deficiency in teaching aids – a problem that is simply corrected. Another example would be finding that an instructor is knowledgeable but not skilled in the art of teaching.

Some training programs are set up to have equipment manufacturer’s representatives on site up to three months during introduction of new equipment. In these cases, the representatives often turn into specialized workers and lead hands instead of completing dedicated training programs. This subversion of effort is typical of what often happens when informal or ad hoc training programs are implemented, particularly at remote locations or in developing countries. A training system is not complete without educating maintenance managers and supervisors. A typical first step is a one-week course on PM.

For supervisors, attendance in seminars, conferences, and conventions is a valuable training adjunct, especially if tours of mining facilities in the area are on the post-agenda. Alternatively, independent arrangements can be made for key people to visit with personnel and facilities at comparable mines and to invite reciprocation.

Case History
One large mine in South Africa provided a PM course to 94 maintenance foremen and supervisors. These men scored an average of 18% on a pre-test and 88% on a comparable post-test, for a gain of 70%!

ISO Accreditation
The mine Maintenance Department is not selling services to the public; it is providing services to the mine operators. At some mines, the operator is considered to be the client as part of the implementation and accreditation of ISO 9000. The logic may be arguable, but the necessary procedures for implementation are beneficial in improving the mine maintenance program. At smaller mines and most mines in developing countries, the effort required to receive accreditation is simply not practical.

5. Work Practice
The following components of Work Practice are specific to maintaining the mobile equipment fleet in an underground mine.
• Routine maintenance
• Preventive maintenance
• Unscheduled repairs
• Shop facilities
• Spare parts and supply inventory lists

Routine Maintenance
Routine maintenance (regularly scheduled service) is typically carried out at prescribed intervals as follows.
• Vehicle check at start of shift (by operator).
• 100 hours (wash, grease, and inspect).
• 250 hours (service).
• 500 hours (service).
• 750 hours (service).
• Monthly check (irrespective of machine hours).

Original Equipment Manufacturer Routine Maintenance Intervals
These are a simplification of the routine maintenance intervals typically specified in most OEM operating manuals (following).
• Vehicle check at start of shift (by operator).
• 50 hours (60 hours in West Europeanbuilt equipment manuals).
• 100 hours (125 hours in West Europeanbuilt equipment manuals).
• 250 hours.
• 500 hours (600 hours in East Europeanbuilt equipment manuals).
• 1,000 hours.
• 2,000 hours.
• Annual

Changing Engine Oil
One elementary maintenance exercise is changing engine (crankcase) oil. In an underground mine, oil changes are normally performed on LHD units at each 250 hours of service. The interval may have to be reduced in certain circumstances, particularly in developing countries, such as high sulfur content in the fuel. It is normally specified (and is the law in some jurisdictions) that diesel fuels for use underground have sulfur content of 0.5% or less. Higher sulfur content will often result in SO2 concentrations in the exhaust that exceed the accepted TLV under normal ventilation conditions.

High sulfur content also has a deleterious effect in the engine because it breaks down crankcase oil. Some equipment manuals state that the oil change interval should be halved when the sulfur content exceeds 0.5%. Where surface operations suffer high sulfur content in the fuel, it is recommended that oil changes for rubber-tired loaders be made according to the following chart (the intervals for haul trucks are longer).
Table 28-1 Engine Oil Change Intervals


Fuel Injectors
Another problem with fuel can be that it is not adequately de-waxed at the refinery causing gumming of the fuel injectors. Injectors are expensive and should last for approximately 6,000 hours. Change-out of injectors is an intricate operation that can cause damage if not completed with proper tools and diligence. A temporary remedy is to dose the fuel with a petroleum distillate, such as naphtha gas; however, efforts should then be directed towards obtaining a better quality fuel. The advantages of cleaner exhaust and a return to the normal oil change interval should offset the increase in cost of proper fuel.

Regular diesel fuel sold today in North America by major oil companies is extremely low in paraffin (and sulfur) content. As a result, some operators add automatic transmission fluid (ATF) to the diesel fuel to improve engine lubrication.

Fuel Tank Bleeding
One often forgotten routine maintenance item is bleeding the fuel tanks of water and sediment. The amount of water that can condense inside a fuel tank is significant. Mobile equipment that works on surface or routinely travels to surface from the underground should have fuel tanks topped up when half full, especially in temperate climates. Adding methyl alcohol to the fuel is justified in extremely cold weather, but otherwise methyl alcohol prevents natural separation of the water (that could otherwise be bled off) and reduces the caloric value of the fuel.

Greasing Equipment
Another elementary maintenance exercise is greasing equipment. Common problems include missing some of the many grease points and failing to replace damaged nipples. Broken nipples can be very difficult to remove without proper tools and often they are located in areas that are not easy to access. In such cases, it is not uncommon for a mechanic to leave a problem nipple “for the next guy.” Grease nipples come in a variety of sizes and configurations – it is beneficial to standardize the fittings on the total fleet. In cases of difficult access, pipe extensions can be installed to move the grease nipple to a convenient location.

Hydraulics
The key to avoiding problems with hydraulics is preventing contamination of the hydraulic oil. High-pressure hydraulic valves have narrow clearances that can easily become blocked with a single particle of sediment. Oil should not be put into a machine except through a finely filtered funnel. Hydraulic fittings and hoses should be standardized for the whole fleet making it simpler to crimp replacement hoses on-site. Hydraulic tanks should be kept full to help prevent condensation.

Preventive Maintenance
More than one definition exists for PM. To some, it includes all the routine maintenance items later identified in this chapter. A more specific definition includes those items of routine inspection and maintenance that are prognostic. In this definition, PM also includes additional specific inspections and measurements that predict imminent or future problems, so that change-out or repairs can be accomplished before failure of the component while operating. This specific definition is now typically referred to as “preventive and predictive maintenance” (PPM). This chapter addresses PPM; however, it is identified simply as PM rather than PPM.

Separate Discipline
The PM planning function should be organized as a separate discipline at the mine. The person in charge of the PM program is the PM Technician, reporting directly to the Supervisor of the Planning and Control Department.

PM Technician
The PM Technician is responsible to separately record the results of all PM work at the various routine maintenance intervals, and to implement/record those tests and measurements not specified for routine maintenance, such as random testing of spent engine oil samples. From the results of the measurements and tests, the PM Technician can recommend early repair or change-out of components for approval by the supervisor, implementation by the planners, and execution by maintenance personnel.

Risk-based Assessment
Once a PM system is developed and running satisfactorily, it may be upgraded to include a formal risk-based assessment program. In a risk-based system, the seriousness of each defect is considered and a “safe operating life” is estimated before it is necessary to repair or replace the component (or allow failure to occur).

Inventory Control
The PM program will fail if there is an inadequate supply of spare parts and components in inventory for the mobile equipment fleet. The PM Technician with the assistance of a technician/clerk should be responsible for inventory control of mobile equipment parts and components. The inventory control function includes spare parts and stock item level monitoring, re-orders, and disposal of obsolete items. The PM Technician coordinates efforts with the Purchasing Department and the maintenance planners.

Additional Roles
The duties of an expediter are to locate particular spare parts as well as to provide face-to-face communications and delivery service between the planning office and the underground. The roles of a filing clerk, receptionist/typist and translator are self-explanatory and the services include assistance with the PM program.
Table 28-2 lists typical requirements for PM measurements and tests on the mobile equipment fleet.
Table 28-2 Measurements and Tests for Mobile Equipment Preventive Maintenance
• Testing of spent crankcase engine oil.*
• Testing of service and parking brakes.
• Measurement and adjustment of play inbrake linkage.
• Measurement of wear on the brake discs.
• Measurement of lubricant, radiator, battery and brake fluid levels.
• Measurement of torque on engine mount bolts.
• Measurement of torque on transmission mount bolts.
• Measurement of torque on drive-line bolts.
• Measurement of torque on wheel nuts.
• Measurement of air pressure in tires.
• Measurement of tire wear.
• Measurement of engine crankcase pressure.
• Measurement of pressure to release pilot system relief valve.
• Measurement of steering system pressure.
• Measurement of play in pins and bushings.
• Measurement of play and wear of drive belts.
• Measurement of wear in bucket lips.
• Measurement of backlash in front and rear differentials.
• Check fire extinguisher device for full charge (weigh charge).
• Check for fatigue cracks in operating components.
• Check for leaks in water, fuel, and oil lines.
• Check seal in air bowl (pre-cleaner) of air filter device.
• Check hydraulic line suction filter for damage.
• Check for leaks or damage to exhaust manifold, muffler and tail pipes.
• Check exhaust for excess smoke or particulates.
• Check wheel chocks are not missing.
• Record engine and hydraulic oil temperatures when operating.
.
*Sent to the OEM (or independent laboratory) for analysis to specify the exact oil change interval required and provide predictive and preventive information on engine life 

Unscheduled Repairs
Requests for repairs can result from vehicle start-up inspection, routine maintenance inspection, PM analysis, diagnosis while operating, damage while operating, or breakdown while operating. Some requests may be prioritized and scheduled, but others require immediate attention (unscheduled repair, also called emergency repair). Accommodation for these is made in the Weekly Plan by allocating a significant block of man-hours for emergency repair (perhaps 25% of the man-hours available).

Operations supervisors have a role in directing maintenance efforts for emergency repairs. At some mines, certain key maintenance personnel take field instructions directly from the appropriate mine operator. The maintenance personnel continue reporting to the Maintenance Department for administrative aspects (time sheets, shift rotation, etc.). Those opposing its implementation refer to this procedure as “fragmentation.”

Shop Facilities
A surface shop facility is best for a new trackless underground mine served by ramp access from surface; however, as the mine workings progress to deeper horizons, the surface shop facility eventually becomes obsolete. Because a drill jumbo is the most difficult piece of equipment to drive to surface, the mine eventually begins to service drill jumbos in a small underground shop facility.

Subsequently, it becomes necessary to service LHD units underground at which time a major underground shop is constructed and the “jumbo” shop becomes a satellite facility suitable for fuelling and lubricating equipment. A main shop facility underground represents a major investment for the mine and the location and design are the subject of detailed consideration.

Underground Location
Following are some of the criteria that must be considered when deciding on the location of the underground shop facility.
• The facility should be as close as practical to the “center of mass” of the proposed workings over the balance of the mine life.
• The facility should have convenient personnel access from surface.
• The facility should be located adjacent to the exhaust air stream.

Items two and three may be in conflict. Because the latter is considered mandatory (for reasons of fire safety), typically the shops are located near the ore body as opposed to being near the main shaft access. In most cases, “near the ore body” also means near the internal ramp (which is desirable).

Another requirement is that the facilities be located in an area of good ground. The mine’s rock mechanics department should be engaged to determine the exact location and orientation. If poor ground conditions are unavoidable, the shops must be designed with narrow widths. In some mine locations, restrictive statutory requirements may apply to an underground shop facility, such as, “The welding bay must be located independent from the main shop facility.”

Detail Design
The first step in the detail design of a major underground shop facility is to itemize the maintenance functions in detail. An example of the maintenance function for a typical underground shop facility is found in Table 28-3.
Table 28-3 Maintenance Functions of Main Underground Shops
• High-pressure detergent washing (or steam cleaning).
• 250-hour and 500-hour servicing.
• 1,000-hour, 2,000-hour, and annual routine maintenance.
• Tire rotation and replacement.
• Bent cylinder piston rod replacement.
• Replacement of worn cylinder pins and bushings.
• Bucket lip replacement and hard facing.
• Engine and transmission diagnostics.
• Transmission change-out.
• Engine change-out.
• Wire harness repairs and replacement.
• Headlight and tail light change-out.
• Wheel bearing replacement.
• Replacement of worn hydraulic hose and bent fittings.
• Removal of damaged or defective grease fittings and replacement.
• Bent jumbo boom change-out.
• Replacement of bent drive shafts and damaged universals.
• Replacement of brake actuators.
• Replacement of tire valve stems, wheel nuts and studs.
• Replacement of main hydraulic valve assembly.
• Replacement of water and steering pumps.
• Regular dumping of air filter bowl and fluttering of air filters.
• Cleaning and change-out of air filters.
• Change-out of pellets in oxy-catalyst scrubber.
• Re-calibration of brake discs.
• Replacement of worn center hinge pin and bushing.
• Replacement of planetary wheel end drives.
• Blowing out fuel lines and brake lines.
• Replacement of fuel lines and brake lines.
• Change-out of water pump and fuel pump.
• Brazing of oil radiator (cooler) leaks.
• Replacement of leaking seals and blown “O” rings.
• Battery terminal scraping, greasing, and battery diagnostics.
• Battery replacement.
• Replacement of lost skid plates.
• Replacement of cracked, worn, or stretched drive belts.
• Replacement of frayed hydraulic control cables.
• Replacement of worn out seat belts and operators seat.
• Taking test samples of spent engine oil.
• Miscellaneous minor repairs and replacements.

Satellite Shop
A satellite shop is normally used for shift services, such as refueling, greasing, topping up lubricants, tire inflation, etc. The requirement for satellite shops should be reviewed periodically. A second satellite shop may be required immediately or in the distant future.

Capacity
The main underground shops should have a nominal capacity to handle at least 10% of the underground fleet in repair simultaneously.

Office
The center of the operations should be an office situated with the main work areas in view.

Component Areas
The principal component areas for a typical underground shop are shown in Table 28-4.
Table 28-4 Component Areas – Main Underground Shop
• Parking area
• Cleaning bay
• Welding bay
• Machine shop
• Service bays
• Repair bays
• Lay down areas
• Parts and materials storage warehouse
• Tool crib
• Tire storage and handling facility
• Lube storage area
• Hydraulic hose storage and crimping area
• Office/lunch room area

Stationary and Portable Equipment
Main underground shops are typically equipped with the stationary and portable equipment shown
in Table 28-5.
Table 28-5 Stationary and Portable Equipment
• 10-Lb. portable ABC fire extinguishers (6).
• Mobile Fire Extinguisher (airport style) or Foam Generator.
• Wall mount first aid kits and eyewash station.
• 10-15 ton capacity overhead crane.
• Portable one ton capacity jib crane.
• Chain block, 5 ton for repair bays (2).
• Come-along, ½ and ¾ ton (2).
• Oxygen-acetylene cart (1).
• Hydraulic jack, 10 ton.
• Hydraulic jack, 20 ton (low profile).
• 400-Ampere capacity AC/DC welder.
• Electrode oven, bench size.
• Soldering gun, complete with (c/w) 50/50 solder assortment and flux.
• Pedestal mounted magnetic drill press.
• 6 and 8-inch vise (1 each).
• Anvil.
• Bench grinder with cut-off and grinding wheel c/w dressing tool.
• Bench lathe.
• Tripod mounted, yoke and chain pipe vise.
• 100 ton hydraulic press frame (jack press) for bushings.
• Portable grinder (pneumatic) (2).
• Portable chipper (pneumatic) c/w spare moils.
• 3/8“ portable drill (electric).
• ½” portable drill (pneumatic).
• Set of brake cylinder honers (internal and external).
• ½”drive pneumatic impact wrench.
• ¾” drive pneumatic impact wrench (4).
• ½” drive torque wrench.
• Pneumatic operated grease gun with flex hose end.
• Engine cylinder compression testing device.
• Set of hydraulic jacks.
• 10 Ampere, 6/12 volt battery charger (1).
• Battery voltage tester.
• Battery liquid tester (SG of fluid).
• Hand held volt-ohm meter.
• DC power supply unit, 0- 48 volts.
• Hand held ammeter.
• Milli-ammeter, 4-20 milli-ampereres (for LHD remote controls).
• Ignition timer (diesel).
• Portable suction sand blaster c/w hose, nozzles and protection gear.
• Pressure gauge, 60 bar, c/w hose and custom connectors.
• Pressure gauge, 250 bar, c/w hose and custom connectors.
• Desktop computer to display electronic parts catalogues.
• Safety basket for pressurizing tires.

The underground shops should be equipped with the hand tools, stock items, furnishings, and sundries shown in Tables 28-6, 28-7, and 28-8.
Table 28-6 Stock Items
• Selected inventory of mobile equipment spare parts (in underground warehouse).
• Assortment of “free-issue” items (e.g. coarse thread machine bolts, nuts and washers in open boxes outside warehouse – no paperwork required when taken).
• Assortment of emery and wire cloth.
• Assortment of machinist’s bar stock.
• Assortment of springs.
• Assortment of brass shim stock.
• Assortment of cotter pins.
• Assortment of snap rings.
• Assortment of machine screws.
• Assortment of valve stems and key caps (for tires).
• Assortment of all-threaded rod (coarse thread).
• Cardstock and tag assortment – for lockouts, etc.
• Stock of impact wrench sockets (metric and Imperial).
• Assortment of “Tyrap” plastic wraps (to bundle hydraulic hoses).
• Drill index 2mm to 12mm x 1mm.
• Drill index 1/16 inch to ½ inch x 1/64 inch.
• Gasket material assortment and cutting knife.
• Cylinder packing material assortment.
• V-belt (drive belt) fabrication kit and assortment of belting sizes.
• V-belt (drive belt) dressing compound.
• “O” ring assortment.
• “O” ring fabrication kit.
• Brake repair kits.
• Grease fitting assortment.
• Assortment of ductile copper tubing.
• Assortment of plastic pails c/w handles.
• Roll of automotive wire.
• Roll of mechanic’s wire.
• Roll of haywire.
• Roll of 4/0 welding cable.
• Welder’s soapstone (1 case).
• Stock of clear (“throw-away”) and colored lenses for welder’s helmet.

Table 28-7 Furnishings and Sundry Items for Underground Shops
• Metal work bench (5).
• Metal saw horses (2).
• Welders helmet.
• Welding screen.
• Oxy-acetylene stand and cart.
• Cutting goggles (2 pr) c/w spare lenses.
• Strikers (2) and spare flints.
• Cutting tips, one each of Nos. 1, 2, 3, 4, 5, 7, 9.
• Brazing tips, one each of Nos. 1, 2, 5, 7, 9.
• Rosebud heating tip.
• Set of tip cleaners (reamers).
• “Stinger” (welding electrode holder) (2).
• Welding apron and poncho (for overhead welding).
• Assortment of welding rod (7018, 6011, cast iron, stainless, bronze, arc air).
• Portable rod holder container (2).
• Set of battery booster cables (2).
• Trouble lights with 50-foot cord (3).
• Floor creepers (3).
• Assortment of screened funnels.
• Set of chain slings with barrel hooks (1).
• Barrel spouts (3).
• Barrel faucets (4).
• Rough duty trouble lights (2).
• Snake flashlight (1).
• Plastic “redibins” (50) (for storage).
• Work order storage rack.
• Bookcase for operating and spare parts manuals.
• Tilt and tow fireproof trash containers (4).
• Assortment of squeeze bottle and oiler cans.
• Penetrating oil and/or WD40.
• “Loctite®” (250 ml): 271, 277, 242, 504.
• Dye penetrating flaw detector kit.
• Tote trays for hand tools (3).
• Canvas tote bags for hand tools (12).
• Set of peg boards complete with hooks and fixtures.
• Stable brooms (2).
• Mops complete with wringer.
• 10 feet by 5/8”choker slings (2).
• 10 feet by ¾” choker slings (2).
• Carboy of distilled water for batteries.
• Hand cleaner dispenser and stock of mechanic’s hand cleaner.
• Paper towel dispenser and rolls of paper towels.
• Boxes of clean rags.
• White or black board and notice board.
• Assorted “office” equipment – desk, telephone, PC, etc.

Table 28-8 Hand Tools
• Standard journeyman mechanics tool box assembly of tools (5+).
• Standard journeyman electricians tool box assembly of tools (2+).
• Set of easy-outs (broken-off bolt extractor).
• Machinists tap and die set (metric and imperial).
• Pipe thread, die and pipe cutter set (for small pipe diameters).
• 1-inch drive Johnson power bar and large end socket set.
• Filter wrench (2).
• Set of snap ring pliers (2).
• Set of giant Allan wrenches (metric and imperial).
• Hand held grease gun with flex hose end (2).
• Tube cutter, flaring tool and bender set.
• Oxygen-acetylene cutting assemblies complete with gauges (2).
• Welder’s chipping hammer (2).
• Tire valve tool kit, complete with stem rethreader, core tightener/remover, stem tool complete with chain to pull core through rim.
• Compressed air tool and fittings kit complete with blow gun.
• Dropped nut retrieving magnet.
• Magnifying glass (loupe).
• Machinists square (metric/Imperial).
• Bead breaker pry bar.
• Set of long pinch bars and levers.
• Assortment of wire brushes.
• Assortment of wheel wire brushes to fit portable grinder.
• Assortment of circular cut-off disks to fit portable grinder.
• 24” channel lock adjustable wrenches (2).
• 18” adjustable spanner wrenches (Westcott).
• 24” adjustable spanner wrench (Westcott®).
• 24” adjustable pipe wrench.
• 36” adjustable pipe wrench.
• 2 Lb. sledge hammer (6).
• 1.5 Lb. ball peen hammer.
• 10 Lb. double jack sledge.
• 12 oz. rubber mallet (2).
• Bearing puller tool sets (2).
• Straight line micrometer.
• Set of feeler gauges (2).
• Assortment of ‘C’ clamps.

6. Operating Environment
In the past, the Maintenance Department had little to do with the operating environment, but this has changed. Implicit in an optimized maintenance system is dialogue between operations and maintenance personnel that cuts both ways.
Operating Environment may be subdivided as follows.
• Equipment operator qualification
• Vehicle start-up check
• On-board diagnostic and prognostic devices
• Haulage route design*
• Haulage route maintenance*
• Dust control*
* These items are discussed in other chapters of this handbook.

Equipment Operator Qualification
Inexperienced and careless vehicle operators (and poorly maintained haulage routes) will destroy the best fleet maintenance program. For this reason, training and qualification programs are an important supplement to an efficient maintenance system.

Vehicle Start-up Check
At the beginning of the shift, the operator performs a vehicle check and completes a card. The checklist on the card is reproduced from the one found in the operator’s manual. Some checklists are extensive, but all include checking the levels of engine oil, transmission oil, and hydraulic oil. The lists also include checking each brake system. Most require emptying the air cleaner dust cup. While it is the vehicle operator that completes this check, it is generally considered a routine maintenance item.

On-board Diagnostic and Prognostic Devices
Modern LHD units equipped with on-board diagnostic and prognostic devices can expect much longer life. One modern underground mine reports that they have achieved 20,000 hours of useful life on their LHD units without major rebuild.

7. Appendix
The following information is provided to augment the data contained in this chapter. The information is divided into the following sections.
• Logs and Certificates
• Sample Work Standard
• Work Standard Abbreviations
• Mine Hoist Lubricants
• Mine Hoist Tools and Equipment

Logs and Certificates
Following is a list of logs and certificates that may be required for a typical hard rock mine.

Logs
• Powder and Fuse Magazine Record Book.
• Hoistman’s Log Book.
• Hoisting Machinery Record Book.
• Rope Record Book.
• Electrical Hoisting Equipment Record Book.
• Record of Overhead and Mobile Crane Inspections.
• Hoistman’s Medical Record Book.
• Diesel Equipment Log Books.
• Shaft Inspection Log Book.
• Shaft Water Log Book.
• Noise Level Record Book. Certificates
• Plant and Pressure Vessel Registration Certificates.
• Professional Engineer Certificates and Licenses.
• Certified Technician Certificates.
• Operating Engineer Certificates.
• Hoist Operator Certificates.
• Compressor Operator Licenses.
• Hoisting Rope Test Certificates

Work Standards Abbreviations
Table 28-9 contains standard computer abbreviations for work (performance) standards.
Table 28-9 Work Performance Standards Abbreviations



Mine Hoist Lubricants
Table 28-10 shows lubricants for drum shaft bearings, gears, and oil accumulators.
Table 28-10 Mine Hoist Lubricants


Mine Hoist Tools, Equipment, and Supplies
• Tools and equipment not normally found elsewhere at the mine site.
− Kellums grip
− Rope calipers
− Wire rope gauge (s)
− Rope preforming tool
− Guide template
− Rope clamps, four bolt
− Chinese finger
− Serving tool for applying seizing wire
− Rope winder/tensioner winch
− Deflector sheave
• Tools and equipment dedicated to the hoisting plant.
− Emergency oxygen supply kit (for hoistman at high altitude or underground).
− Dry chemical fire extinguishers.
− Set of slings and chokers.
− Torque wrench.
− 24” channel lock wrench.
− Oil can with long flexible spout.
− ‘O’ ring identification gauge.
− Volt-ammeter and Megger.
− Walkie-talkie set (dedicated channel, leaky feeder).
− Two small portable tugger hoists (3,000 Lb. pull).
• Supplies dedicated to the hoist plant
− Spare hoist ropes.
− Rope dressing.
− Rope seizing wire, 15 gauge serving wire (0.072 inch).
− Track limit cable (aircraft cable).
− Bell cord (aircraft cable).
− Set of wire and bronze brushes.
− Guide bolts.
− Tugger rope clips.
− Hoist lubricants (see Appendix IX).
− Babbit material (if applicable).
− Brass shim stock.
− Silver solder
− Cardstock tag assortment - for lockouts, etc.
− ‘O’ ring kit and assortment.
− Grease fitting assortment.
− Visible dye penetrant kit or spray can.
− Gasket kit.
− Dial chalk.
− Loctite®
− Set of easy-outs.
− Crocus Cloth.2
− IDEAL flexible abrasive strip.2
− Wood alcohol (methyl hydrate solution).2
− SAE - 5W motor oil.2
− Trichlorethylene.2

2- for Lilly controllers