“Cummins Power Generation and Terex Corporation have had a long-standing relationship,” said Larry Fetting, director, Global Rental Segment Development, in a written statement ”We are excited about our investment to acquire the Terex assets. We see this as a natural next step in our commitment to exercise more control concerning our rental product manufacturing requirements and to support the growth of our rental business, with the primary goal of enabling us to better meet the needs of our customers.

“Even more important,” Fetting added with emphasis, “our customers can be assured that this acquisition reaffirms our dedication to providing them with an enhanced level of rental product quality, reliability and service. This new “one-stop shop” structure strengthens a number of our rental requisites: better communication with distributors, increased options and faster response to customers, and a wider array of available products overall.”

Cummins will assume aftermarket support (parts, service and warranty) for the Cummins Power Generation and Terex rental generator product lines on July 21, 180 days post-sale.

In addition to expanding its product offering from the Fridley, Minn., facility, Cummins remains committed to providing industry-leading fuel-efficient, high performance low-emissions diesel engines to generator original equipment manufacturers (GOEMs) internationally.

Joe Feldman, G-drive sales and marketing manager noted in a press release, “Cummins Power Generation has been investing in a comprehensive G-drive product line to help OEMs and delivery partners transition to T4i-compliant products for 2011.”

Products include alternators, generator-drive engines and pre-integrated power systems, combining generator sets and power control and transfer technologies. Services range from system design, project management, financing and operation and maintenance contracts to development of turnkey power plants.

by Daniel C. Brown, Contributing Editor

In today’s economy, everyone is trying to stretch dollars as far possible, and the aggregates industry is no exception to this trend. With nearly 40 percent of respondents to Aggregates Manager 2009-2010 Forecast study who reported they intend to decrease capital spending this year, many operators throughout the nation are looking for ways to extend equipment life at their sites.

What does this mean for day-to-day operations? Many operators run equipment for more hours than normal. Capital for new machines is scarce so equipment is being kept longer and worked harder. Knowing that the equipment has to last, managers carefully watch oil samples for wear particle signals that mean component failure is approaching. And some equipment managers are even replacing small components, such as water pumps and alternators, before they fail.

Finding the “sweet spot”

Although at first glance, longer equipment life may cause concerns, the actual age of the equipment isn’t the key parameter, says Dan Connelly, vice president of equipment services, Oldcastle Materials Inc. in Atlanta. With about 40,000 pieces of rolling stock and eight divisions, Oldcastle is one of the nation’s largest integrated construction materials companies.

 Connelly says that because its demand is down, Oldcastle’s equipment is being kept longer. But, he adds, the equipment is not working its usual number of hours. “Operating hours, not calendar days, is the important factor in determining our replacement cycles,” Connelly says.

He says Oldcastle strives to replace most equipment at the “sweet spot” — the optimum point in a machine’s financial life just before its repair costs balloon and major components need to be replaced. Oldcastle determines its own sweet spot for each category of equipment, based on historical records and analysis of owning and operating costs.

However, in some categories of equipment, such as 7-cubic-yard wheel loaders, Oldcastle considers going for a second life by replacing major components. Forty-ton and larger rigid frame haul trucks would also be considered for major component replacements. The company owns about 500 dozers and 800 excavators, but “typically we don’t rebuild them,” Connelly says.       

How about replacing small components before failure? Yes, says Connelly. “We certainly attempt to replace components such as starters, alternators, and water pumps before failure,” he says. “We advocate condition-based maintenance.”

The level of service that Oldcastle procures from equipment dealers depends on the relationship of each division with its local equipment dealers, Connelly says. Each division has multiple shops that do preventive maintenance and some repairs.

Oldcastle also uses Viewpoint management software, which has an equipment module that identifies each piece of equipment by a unique number. Revenues, as well as operating hours and all costs, including oil changes, parts, and repairs, are tracked for each piece of equipment. “We take data that is housed in Viewpoint to determine the optimum equipment life cycles,” Connelly says. “We look at each piece of equipment multiple times each year.”   

Keeping it longer

The Washington Division of URS Corp. keeps equipment based on site-specific applications, says Bob Merritt, director of maintenance at the Boise, Idaho-based firm. The Washington Division owns 2,000 plus pieces of equipment that work at construction sites, quarries, and mines around the world. 

 “We keep equipment on long-term projects based on application and production,” Merritt says, noting that while many operators try to get rid of machines before the first major rebuild, his company may hold it longer and go through one or two rebuilds on many pieces. “The number of hours is driven by the class of equipment,” he adds.

Take 50- to 70-ton excavators, for example. Washington has some that range from 14,000 hours up to around 25,000 hours on longer-term projects. Front shovels and mining excavators run longer — up to 60,000 hours.

How about dozers? “Typically we try to get rid of the less-than-300-horsepower class at about 10,000 to 12,000 hours; the 300- to 500-horsepower class in 20,000 hours, and the above-500-horsepower class in 50,000 hours,” Merritt says. “Even at those hours, that’s longer than most people run them.”

Washington Division will do a major rebuild at 12,000 to 14,000 hours on a construction dozer. That means the complete power train gets rebuilt components —engine, transmission, torque converter, and final drives.

Why keep equipment longer? “If it adds value, we do it,” Merritt says. “In the last few years, until the downturn, it’s been difficult to get the equipment we needed. The low availability of new and used equipment made the price go up. Now, with the change of the economy, lots of equipment in the smaller- to medium-sized classes is currently available.”

Planning for the long term

While lower-than-normal demand and slim profit margins have swayed some operators to keep equipment longer than planned, they run the risk of catastrophic failure if the machine is pushed beyond its limits. The two main concerns are having an equipment failure cause the entire plant to shut down and losing any residual value of iron assets that are not saleable. If a company decides to hold onto equipment, planned, predictive maintenance and component change-outs are recommended.

 “Through scheduled maintenance, we’ve gotten as many as four life cycles, or 24,000-plus hours, out of large wheel loaders,” says Mike Monnot, vice president of equipment for Worcester, Pa.-based American Infrastructure. The wheel loaders work for a subsidiary called Independent Construction Materials. He recommends getting expected component lives from the manufacturers, then watching all indicators of wear — oil samples, vibration analysis, wear measurements, and the like. “You come as close to that end of life as you can,” he says. 

Through careful planning and proper maintenance, operators who plan to delay capital expenditures can extend the number of hours they get from their mobile equipment. But best practices for equipment maintenance make sense for all operators, not just those looking for longer equipment life.

Quick Tips

To keep mobile equipment running smoothly, consider the following guidelines.

Haul Trucks

-         Perform daily maintenance according to manufacturer recommendations;

-         Clean windows and mirrors;

-         Check front and rear lights;

-         Inspect the seat belt;

-         Review electronic fluid monitoring and air filter reports;

-         Use clean fuel with low sulfur content; and

-         Avoid over-servicing the machine.

Excavators

-         Check coolant level;

-         Check engine and hydraulic oil levels;

-         Drain water from fuel separator/tank;

-         Test indicators and gauges;

-         Inspect the undercarriage and track adjustment;

-         Inspect the boom, stick, and bucket and lubricate linkages;

-         Inspect the seat belt; and

-         Test the travel alarm.

Wheel Loaders

-         Perform regular sampling and oil analysis;

-         Check coolant level;

-         Inspect linkages;

-         Inspect the bucket and its cutting edge; and

-         Look for leaks from hoses and cylinders.

Tires

-         Select the right tire for the application;

-         Follow the manufacturer’s air pressure recommendations;

-         Check tire pressures at the start of a work shift;

-         Train operators on proper procedures;

-         Remove hazards from haul roads and workways; and

-         Follow the recommended maintenance schedule.

By Therese Dunphy, Editor-in-Chief

 Unplanned downtime. It’s an operator’s worst nightmare. It’s costly. It’s embarrassing. And, it’s avoidable. In today’s economic environment, many operators are trying to squeeze every last ounce of productivity out of their equipment. The challenge is to understand the difference between prodding a machine to peak efficiency and pushing it beyond its limitations. The first option leads to more tons per hour, more efficiency, and a better bottom line. The second can grind a plant to a halt, resulting in lost production and profits.

To avoid this costly scenario, remember these basic tips for keeping your plant up and running.

1. Operate equipment within its design parameters. Understand the key limitations to each piece of equipment. For example, review the crushing capabilities, volume limitations, and horsepower for each crusher at your operation. Based on the mineralogy of your deposit, know which engineering factor is most likely to limit the equipment’s production rate and respect it.

If pushed beyond intended operating conditions, equipment fatigue can set in. This damage is permanent and progressive. It often leads to premature equipment failure.

2. Practice preventive maintenance. Equipment manufacturers provide handy reference guides to their equipment with daily, weekly, monthly, and even periodic maintenance recommendations. These guidelines are developed to prolong equipment life and should not be relegated to the bottom of a drawer or filing cabinet. Keep them posted prominently and ensure that they are being followed.

When inspecting a screen, for example, check the screen tension, fastening system, and supporting structure. If using spray nozzles for dust control, check to see if water pressure has created an uneven wear pattern on screen media. Planned downtime can be arranged to work with, not against, the site’s production goals.

3. Identify the cause of equipment failure. As one crushing expert told Aggregates Manager, “Anyone with minimal mechanical aptitude is capable of changing a broken crusher part when it fails, but nine out of 10 times, the same crusher part will fail again because no one was able to identify and eliminate the root cause of the initial failure.”

By inspecting failed parts, gathering information from operations and maintenance personnel, and observing equipment trending information prior to failure, underlying problems can be pinpointed, and corrective action can be taken.

4. Take time for a lube stop. Aggregate operations create extreme operating environments. Selection and use of the proper lubricant helps improve equipment reliability and extend its life. Make sure the lubricant used on each piece of equipment — whether stationary or mobile — meets manufacturer specifications in terms of viscosity, oxidation stability, and additives. If the oil is too thin, equipment wear increases. If it is too thick, it requires more energy to lubricate moving parts.

To avoid cross contamination, label or color code storage containers, dispensing equipment, etc. And, don’t ignore the benefits of an oil analysis program to identify small problems before they become costly ones.

5. Stock wear parts on site. To keep equipment maintenance on the fast track, eliminate the need to wait for a part to be delivered by keeping standard wear parts on site. Common items such as screen media, crusher blow bars, liners, and rotors should be available for quick change outs. Remember to follow storage guidelines to keep consumables in proper condition.

6. Educate employees. Equipment is expensive and downtime can be even more so. Invest in employee training to ensure they understand how to operate and maintain equipment. Begin with an assessment of each employee’s current knowledge. Identify gaps in education and provide specific, measurable training that will improve their skills and prolong equipment life.

These six steps provide an overview of ways that aggregate producers can extend equipment life. Maintenance personnel and manufacturer representatives can provide specific guidance on additional procedures that can benefit your site. While trying to control costs, just remember that an investment in proper equipment maintenance and staff training is far less costly than the potentially catastrophic costs of unplanned downtime. 

Quick Tips

To keep equipment up and running, implement the following maintenance guidelines.

Impact crushers

• Turn blow bars every 20,000 to 25,000 tons;
• Replace blow bars when they are 1.25 inches from the rotor surface; and
• Watch side liners for wear near the rotor and turn them between 50,000 and 75,000 tons, depending on mineralogy.

Jaw crushers

• Learn the wear pattern for your crusher type and maintain accordingly;
• Change wear liners at proper intervals; and
• Allow manganese to “work harden” by crushing softer or less abrasive material — when possible — after installing a new liner.

Cone crushers

• Follow manufacturer recommendations for reduction ratios;
• Check liners daily for wear and begin inspecting for cracks and failure when they reach 25 percent of their expected life; and
• Change the liner if production rates decrease by 10 percent.

Screens

• Inspect screen media for excessive or patterns of wear;
• Ensure proper tension; and
• Check calibration of the screen’s throw to ensure proper material movement across the screen.

by Christina Fisher

When it comes to hydraulic breaker maintenance, proper equipment operation is as important as routine preventive maintenance. These two factors work simultaneously to keep a breaker operating at peak efficiency with minimal downtime.

Operator training: back to basics

“When I conduct a seminar, I really stress operator training,” says Jeff Graham, technical support representative for Atlas Copco Construction Equipment. “Improper operation can really destroy a breaker just as much as a lack of maintenance.”

1. From the outside to the inside. Don’t start breaking in the middle of the material. The breaker may not be able to break the rock very quickly. The working tool could get lodged in the material or overheat. It’s like eating a sandwich. You don’t start in the center; you start at the outside and work your way in, taking small bites to work your way into the material. Starting in the middle will increase the likelihood of extended cycle times.
2. 90 degrees, please. Always work 90 degrees to the work surface. (This is not the same as 90 degrees to the ground!) When an operator works at an angle, the tool is put under stress and can break.

“This is why we put breakers on excavators,” Graham says. “The excavator can angle the breaker in different directions so that you can obtain that 90 degrees to the work surface of the material you’re working on.”

1. They’re breakers­­­­, not drills. Never place the breaker straight down into the material like a drill, which can cause the tool to get wedged into the material. Instead, slightly rock the breaker 5 degrees in either direction. This allows the dust and debris to come out of the hole in order to easily remove the tool when you are ready to move.

“You rock the breaker to find the sweet spot,” Graham says. “It’s like playing golf. There’s a certain spot on your golf club that you want to make sure you hit to get the most power and the farthest drive out of your hit. It’s the same thing with a breaker. By finding the sweet spot, it reduces the amount of wear on the bushings and allows the breaker to work more efficiently.”

1. Break, don’t pry. Never pry material apart with the breaker. It’s not designed to break by prying, which can damage the tool. Instead, break larger material up into smaller pieces.
2. No progress? Time to move on. One of the most important things an operator can do is to avoid extended run time. “This is a common error,” says Matt Cadnum, vice president of aftermarket for Atlas Copco Construction Equipment. “Our specs indicate a run time of no more than 30 seconds in any one place, but a good rule of thumb is that if the material is not breaking in 10 to 15 seconds, then the operator should reposition the working tool.” 

A lack of progress also indicates that the breaker may be improperly sized for the material. “When the debris and dust stop coming out of the hole and settle at the bottom, the tool is actually beating on the dust,” Graham explains. “The breaker is not transferring its energy from the tool to the material. Breaking power is decreased, and you lose that energy. That lost energy is turned into heat from the friction. This heats up the end of the tool and starts to distort and destroy it.”

This excess heat can also damage the auxiliary hydraulics on the carrier because it’s working harder. “The carrier is only designed to handle a certain amount of generated heat from the attachment,” Graham adds. “If you run the breaker for long periods of time, you can overheat the carrier as well, and the cooling system for the carriers won’t be able to handle it.”

Maintenance: All day, every day

By putting some simple steps and procedures into practice throughout the day, an operator or technician can keep a hydraulic breaker operating at peak efficiency for longer periods of time.

Each morning, visually inspect the breaker and the carrier. Make sure nothing is cracked and that the hoses are intact and properly attached. The most important thing an operator can do, however, is to ensure that the breaker and the tool are greased properly.

“Several times a day the operator should draw the tool up near to him so he can see the tool and the bushing. He doesn’t even need to get out of the cab,” Graham says. “The operator should see wet black grease. If the tool looks grainy or powdery, then it’s very dry and not getting enough grease. If the tool is shiny, it’s not getting any grease at all.”

At this point, the equipment needs to be shut down to determine what is causing the lack of grease, whether it has run out of grease, a grease hose has broken, or the central lube system is malfunctioning.

“Many customers in the field don’t realize how critical it is to lubricate the bushing and the tool, so their operators don’t do it,” Cadnum says. An automatic lubrication system, available on some breakers, prevents damage due to improper lubrication.

A breaker should be lubricated every two hours at a minimum. A breaker cannot be over-greased unless it’s done improperly. Whenever a breaker is being greased, there needs to be down pressure on the tool so that the grease will not be forced up into the impact area of the tool and piston. The grease should travel down the tool to the area where the bushing is and exit the breaker.

Graham says that operators often ask how much grease should be used each day. “Different applications call for different amounts of grease. Longer cycle times mean more grease. If the material is light and it doesn’t take much to break through it, then less grease is needed. It all depends on the material,” he says. “The most important thing to do is to check the tool multiple times a day.”

It’s not just the lubrication process itself that is important, however. It’s using the proper type of lubricant. “Using an off-the-shelf grease won’t work,” Cadnum points out. “You need something specifically made for hydraulic breakers. The stresses are such that the machine is very demanding and its needs (are) very specific. The amount of friction, side loading, and heat on a breaker requires a tough lubricant with a high dropping point, and usually some solids added as well.”

Many manufacturers offer a type of grease with copper particles added to it. When all of the grease is pushed out of the breaker, the copper particles act like miniature ball bearings, providing some lubrication in a binding situation.

It is also important to regularly check that the breaker and the carrier are properly adjusted. “Most hydraulic excavators allow the operator to adjust the hydraulic input to the breaker right from the cab,” Cadnum says. “It’s extremely important that the operator understands what setting is appropriate for that hydraulic attachment. If the setting is incorrect, it could damage the breaker.”

Graham adds that when a breaker is moved to a different machine, the carrier needs to be flow tested and properly adjusted for that breaker. “Otherwise, it can really reduce the life of the hydraulic seals inside the breaker. Anytime the breaker has been rebuilt — and annually, at a minimum — the carrier should also be flow tested and adjustments made as necessary.”

Proper storage is essential

Finally, at the end of the day, the breaker should be stored standing upright. This takes the weight of the piston off the seals. Storing in this position also helps to keep rain from getting into the vital areas of the breaker. The shiny surface of the piston is exposed when the breaker is not running, and if the breaker is lying flat, water can sit on the piston and cause it to rust. If it’s not feasible to stand it upright, the best alternative is to elevate the bracket end of the breaker that attaches to the machine. Place a tarp over the tool end of the breaker to protect it against the rain.

Breakers can be very expensive to repair. However, “if you’re doing your routine maintenance and operating the equipment correctly, you should be able to schedule repairs when you are ready,” Graham says. “The whole idea is to ‘pick your downtime.’”

by Marc Lovallo and Alan Tindall

Proactive maintenance is described as preventive, planned, and predictive — while reactive maintenance is simply a run-it-until-it-breaks approach. Indeed, the latter leads producers into a costly crisis mode. Regarding synthetic screen media, proactive maintenance delivers numerous benefits — maximum cost efficiency and uptime, longer wear life, consistent specification accuracy, and the security of a reliable and sound screening system.

Proactive maintenance appears to be a no-brainer, yet in reality, according to a recent survey, nearly 50 percent of plant operators consider their maintenance practices to be merely satisfactory or poor. The remaining 50 percent rank themselves in the good to excellent category — and this top half is arguably the clear winner where profitability is concerned.

With that said, let’s take a look at some media maintenance matters that are guaranteed to maximize the payback of your synthetic screen systems.

Periodic inspections

Due to its long wear life, it’s common to find a set-it-and-forget-it attitude surrounding synthetic media — and that should be avoided. It’s very important to inspect your synthetic screen decks periodically for loose panels or unusual wear patterns which may be caused by a change in feed rate or by high-pressure spray water, for example. Consider that if a screen panel is not replaced before it is worn entirely through, it could result in out-of-spec material, damage to the fastening system, or even to the steel supporting deck.

Monitor quality control samples

Regular sampling can tell producers a lot about the wear life and condition of the synthetic screen panels. A sudden or gradual change in specifications indicates a need to inspect the screen deck for wear. Operations that do not conduct frequent sampling may not realize that the deck has worn to a point that material is out of spec.

Fixing the feed box

Consider lining your feed box (and discharge lips as well) with the same high-quality synthetic material that is used on the screen deck itself. This will help prevent a premature failure of the feed box. Prone to much wear, steel feed boxes are most often patched and plated in an attempt to extend their useful life — a tactic that affects the feed distribution of the material onto the screen deck itself, creating more impact and causing excessive wear at the feed end of the deck.

Check side wear liners

Synthetic side wear liners are bolted or clamped onto the side of the screen box to protect the walls of the deck and to hold the synthetic screen panels down along the outside edge. As side wear liners typically last longer than the actual screen surface, they are often overlooked during inspections. Side wear liners should be checked for wear and for any loosening of the bolts or clamping hardware. If all liners are not securely tightened, screen panels can move, resulting in damage to the side wear liners, the screen panels themselves, or even to the modular screen system support structure. Loose side wear liners can also allow screen panels to disengage, causing material to go out of spec.

Proper support and tensioning

Support side-tensioned synthetic screen mats with high-quality bucker bar rubber. Do not use the same bucker bar rubber that is used with wire cloth. It is also important to tension the screen properly upon installation and to re-tension the mats on a regular basis. As steel wears more quickly than the synthetic material, do not use standard steel products to clamp down the screen in the center. Instead, use components that are compatible with the screen surface, either rubber or polyurethane.

Protect the screen surface during repairs

Take the proper precautions when welding on or near the screen deck by protecting the synthetic screen surface from damages caused by hot steel or sparks. Before beginning, spray the entire deck down with water and cover it with a fireproof blanket or plywood sheets. Keep a hose near the work site in case additional water is needed.

Follow recommended replacement & installation methods

First, make sure that you complete any necessary repairs (such as replacing worn cross members) to the screen box itself before you install a new screen deck. Also, make sure the screen machine is thoroughly cleaned before installation. When installing new screen panels, lubricate the outer edges with soapy water. This will allow them to go in more smoothly. Do not use WD40 or any oil or petroleum-based products for lubrication as it will cause a deterioration of the synthetic material.

When replacing worn screen panels, clean any dirt, sand, or grime buildup from the steel support work and fastening system to allow the new panel to properly lock itself in place.

Post and follow a deck layout sheet

If your media supplier has provided you with a diagram of the deck layout, post it as a reference tool for the maintenance crew. This is especially important if the deck layout contains a number of different panel types and opening sizes. This will ensure that the correct layout is maintained as panels are replaced — and will ensure that the deck design remains accurate for the given application.

Maintain maintenance records

Keep records on what, where, and when screen panels are replaced. Note the location of the panel and the date of replacement. This will allow you to document the wear life of each panel and will aid greatly in the forecasting and future purchasing of replacement panels — and the overall budgeting for yearly screen costs.

Proper care and storage

During an extended plant shutdown, protect your equipment investment from weather, ice, or sun damage by covering your screen decks with a tarp or with plywood. If you are stockpiling replacement panels, stack and store them inside the maintenance building in a cool, dry area. Never stack or store them outside and under the heat of the sun.

Choose a detail-oriented media manufacturer

Working with the right screen media manufacturer or dealer is imperative. You should choose a vendor who will take the time to analyze every detail of your application in order to specify the right screen media solution. Choose a hands-on vendor who will conduct a complete evaluation of your screening circuit at various points before, during, and after your production season.

Proactive vs. reactive

While the reactive run-it-until-it-breaks strategy may be appropriate when operating a light bulb, it is obviously not recommended for major processing equipment. The goal of all good maintenance programs is to maintain the reliability of your valuable equipment by repairing or replacing worn components before they actually fail. This keeps your screening operation running and helps prevent emergency breakdowns.

While the use of synthetic screen media definitely reduces maintenance labor requirements, it does not eliminate it. Be proactive with media maintenance. Doing it the right way will maximize the payback. Cutting corners will cost you more in the long run.

Marc Lovallo is the vice president of sales for Polydeck Screen Corp.; and Alan Tindall is the Polydeck regional sales manager for the West Coast. Polydeck Screen Corp. is a Spartanburg, S.C.-based manufacturer of modular synthetic screen media systems.

by Mark Kestner, Ph.D.

Water spray systems have long been used to control dust produced by quarry operations. They protect workers from exposure to silica containing dusts and prevent visible emissions that upset neighbors. But what happens when the temperatures drop below freezing and winter weather challenges operators that have to keep spray systems running?

Once the leaves begin to fall and the north winds begin to blow, it’s time to winterize your spray system. An early frost can catch the plant unaware and freeze up hose, pipe, and nozzles. If the pump freezes up and bursts, that’s real trouble. When this happens, the plant can’t operate until the system is thawed or repaired and that means lost production. If operators have to spend a couple of hours a day thawing out nozzles, the dollars can really add up. The busy quarry operation would be wise to plan ahead and install a system that will minimize downtime during the winter.

Here are some guidelines for operating spray systems in cold weather:

1. Install a thermometer to alert operators to freezing temperatures so they can take action before nozzles freeze up.

2. Inspect spray nozzles daily to make sure that they are not plugged or frozen.

3. Inspect the pump daily. Verify that the pump is heated and that the inlet water line is not frozen.

4. Minimize the number of spray nozzles in service. Use only essential spray nozzles.

5. Consolidate spray nozzles. Using a single nozzle instead of two or three nozzles at the same spray point reduces the number of nozzles to maintain and allows the use of larger orifice nozzles that are less likely to freeze.

6. Make sure that nozzles are properly targeted and do not spray steelwork or conveyor belting.

7. Make sure water lines run straight and true and that drain valves are located at all low points where water can collect.

8. Drain water lines and nozzles immediately after they are taken out of service and leave drain valves open overnight. Do not allow water to sit in hose lines and spray manifolds.

Many quarries have taken winter operation a step further and installed compressed air and anti-freeze purge systems to protect water lines and nozzles from freezing. These add a serious measure of protection that any state-of-the-art quarry can ill afford to be without.

Advanced wet suppression system designs consolidate all moving parts onto a skid-mounted pump module where they can be protected. No solenoid valves are located outside where they can freeze and burst. Most importantly, the pump module must be housed in a heated enclosure. Thermostatically controlled convection or forced-air heaters can also be mounted directly on the pump skid to keep critical components from freezing. For portable plants, the pump module, surge tank, or other accessory equipment can be housed in a heated trailer.

Hose or pipe is used to supply water to nozzles. Hose has the advantage of being a better insulator and won’t freeze as fast, but it cannot be thawed with a torch like pipe.

In a typical spray system layout, water is supplied to various treatment zones in the plant. For example, in a primary crushing plant, Zone 1 is typically a feed hopper where nozzles are used to control dust when trucks dump. Zone 2 is a primary crusher. Zone 3 is a scalping screen and so on. Each zone is independently controlled using a solenoid valve that is switched on or off from a remote panel in the control booth.

As a practical matter, high-pressure spray systems can be operated down into the 20-to 25-degree (Farenheit) range. Below these temperatures, nozzles will start to freeze even while they are spraying. To operate continuously in sub-freezing temperatures, water lines have to be heat-taped and insulated. Using an anti-freeze solution of a glycol or brine is another alternative, but both methods are expensive, and using anti-freeze agents may affect the chemical and physical chemistry of the stone. Brines are also corrosive and may require special materials of construction in a spray system. Corrosion inhibitors can be added to brines, but significantly increase cost.

Spray systems that feature compressed air and glycol purge systems are designed to get the water out of spray lines before they have a chance to freeze. When the operator switches any line supplying a spray zone from the ‘run’ to the ‘purge’ position, the water solenoid valve closes and the air solenoid valve for that line opens. The sequence and duration of the purge cycle is determined by the control logic of a proprietary software program. The switch for the zone that is actively purging blinks to give the operator an indication that the purge cycle is in progress.

Spray systems that include an anti-freeze protection system use glycol to coat the interior of spray lines and nozzles rather than fill the lines with glycol. This conserves anti-freeze and saves money. Once compressed air has blown the line out, the PLC shuts off the air and turns on a metering pump, which dispenses anywhere from a quart to a half-gallon of propylene glycol solution into the line. After 30 seconds or so, the controller shuts the metering pump down and then turns the compressed air back on to blow the glycol down the length of the line to the spray nozzle/nozzles. This coats the interior of the line and nozzles with glycol to prevent nozzle tips from freezing up and drain valves from cracking.

This technology can be adapted to just about any spray system to protect it against freezing weather. This could include equipping the system with a simple manual air purge, all the way up to installing an automated air and glycol purge system complete with thermostatically controlled drain valves.

Installing an automated purge system in a new or existing spray system can save hours of labor thawing or repairing water lines and nozzles and  keep your plant productive regardless of cold weather conditions.

Mark Kestner, Ph.D., aka Dr. Dust, is an expert in the field of dust control technology and has been published extensively on this subject. Projects to control pollution and improve air quality in the industrialized world have taken him to more than 1,500 mines and power plants in all 50 states and seven countries. To contact Dr. Kestner call 800-237-3878 or visit his Web site at www.drdust.com.

by Garrett Forkner and Andy Rieland

It’s safe to say that some of the greatest advances in aggregates processing equipment in recent years have been made in the automation arena. And while the ability for producers to automate such functions as ticketing and billing has been around for at least 30 years, the past 10 years have seen tremendous progress in technology that allows for better equipment performance and more proactive equipment maintenance. Automation technology has improved plants’ abilities to produce material with more consistency, better quality, and greater productivity. At the same time, real-time automated equipment monitoring helps reduce downtime by tracking maintenance needs. In fact, there are automated systems available that can even remotely and automatically make some repairs.

In short — automation has made our lives and our jobs easier.

A high-tech watchdog

It used to be that producers only added automation capabilities to their plants as part of a new equipment acquisition. But today, existing equipment can often accept automated controllers as a retrofit. And this automation typically provides anything from basic machine control to a high level of process control to maintenance and service control.

Most companies, when they seek information about automation, are actually looking for assistance in maintaining the plant. And at the most basic level, an individual automated plant will monitor operational hours to better track scheduled maintenance.

But depending on the automation package the producer selects, a cone crusher package, for example, will enable the system to also oversee such things as differential pressure, checking the amount of coolant and the filter condition in the coolant system, and monitoring temperature and flow differentials in the supply and return lines. By monitoring the level of lubricant in the system, the automation software can help to maintain required temperature parameters. Cone crusher automation can track total motor hours, hydraulic pumps, lube pumps, main drives, and bearing temperatures for longer bearing life. If the cone crusher is a bushing-type model, the automation system often can measure for bushing wear to prevent catastrophic failure.

As for providing the crusher maintenance itself, there are currently automation packages for gyratory crushers on the market that can include such functions as automated greasing systems, which will grease the bushings as a system subcontrol. And because a primary gyratory crusher is sometimes located hundreds of yards or even miles from the rest of the plant, it can be configured to run independently or tied in to the rest of the plant, based on the producer’s needs. Its protective functions and alarms can still be set to provide alerts in the main control room.

For operational controls, an automation system can manage the feed to the processing equipment, and it can protect crushers from overload situations. It usually will handle the latter by sounding an alarm, correcting the loading, or shutting down the equipment. The automation system can track pressure for clamping and the tramp release system. Most systems will automatically adjust crusher settings for production needs or to compensate for liner changes, and they will alert maintenance personnel when it is time to change liners. And if the automated sensors detect problems, they can be configured to shut the equipment down, or they can work to eliminate the problem without shutting down the equipment by sensing variables and making adjustments.

With all of these capabilities, it might seem that an automation package would render human operators obsolete. But today’s automation packages really can’t replace the operator or field service personnel. They are, however, a big assistance in pinpointing and narrowing down the causes of problems. Additionally, automation systems provide safety benefits because remote sensing typically allows for measurement without contact. Even a basic automation package helps with troubleshooting because the data that’s collected can (and should) be checked regularly for trending, which can be interpreted to pinpoint an issue. So, for example, if the operator notes the system re-pressurizes over and over again, he or she should realize it’s not working properly and schedule a shutdown for service.

Improving performance and the bottom line

Automated packages can also help to improve overall plant performance. By logging production, the system allows the plant operator to track productive and unproductive time, so that he or she can analyze the data and compare it to the material produced. Any data can be trended, interfacing off the process equipment to provide operators and supervisors with such information as maintenance needs, schedules, and downtime hours. The operator can then adjust the plant for better performance. Historical data can be tracked remotely or onboard for higher-level management of overall site performance. All of this also helps when tracking the bottom line for the cost of operation.

In a nutshell, real-time monitoring maximizes productivity and reduces downtime by helping to identify bottlenecks, tracking equipment performance, scheduling maintenance, and troubleshooting problems. From a proactive maintenance standpoint, an automated system helps schedule and plan preventive maintenance. From a service standpoint, trending helps operators to troubleshoot, and then plan a plant shutdown and order parts before a failure occurs.

IT issues and technology advances

Advances in technology have created the ability for automation manufacturers to visit a plant’s automation system remotely to help maintain the software portion of the system. While remote service capabilities are not meant to replace a plant visit, remote software maintenance allows the manufacturer to provide system surveys, software product updates, software extensions, and troubleshooting.

Just as with home computers, developments in information technology (IT) can create issues, rendering older software and hardware obsolete. Changes in software seem to come at an alarming rate. Unfortunately, plant owners no longer need to only worry about upgrading a control system during a new equipment acquisition. Because of this, it’s important to keep PC and Windows-based controllers up to date with software and, less frequently, hardware updates.

It’s important to make sure software updates are followed and provide regular checks for security risks — this is done to avoid risks of viruses, hackers, and even accidental harm from an employee downloading a game. The risks grow when the plant is connected to an Intranet or the Internet. In the latter case, manufacturers usually recommend the implementation of a firewall. Also, as a rule of thumb, Microsoft seems to come out with a new Windows operating system approximately every four years. New functionalities and features might mean there is a need to update software or hardware for the system — before it becomes obsolete.

The advantage of remote service capabilities is that the customer avoids downtime and the cost of a field service call, while usually realizing higher performance of the automation system. A DSL, fiber optic, or cable Internet connection is best for remote access to the automation system, although this is not always possible, given the remote nature of some aggregate operations. In this case, a connectivity solution could be provided through radio link or satellite connection.

System maintenance begins with the order

Without a doubt, an automation system helps to maintain aggregate processing equipment. But in an arguably dirty environment, what’s the best way to maintain the automation package itself? Who watches the watchdog?

Maintenance of the automation system begins at the ordering process. Producers should be familiar with the location and operating climate within which the system will work. Specify this information to the automation manufacturer or contractor so he or she can design the correct type of enclosure for programmable logic controllers (PLC) and terminals. The National Electrical Manufacturers Association (NEMA) provides ratings for panel seals to indicate their resistance to such environmental concerns as wet or dusty conditions. The main or mobile command center (MCC) building can also be protected against the environment. Keep temperatures in mind — for the high end and low end of tolerances. Additional environmental control features can be added for the system, such as heaters for winter and air conditioning for hot climates, which could indicate a need for specific ductwork.

When specifying the order, producers should keep in mind, as well, where the human-machine interface (HMI) will be sitting — whether in the central control room or in a remote area. Location can determine a need for a climate-controlled enclosure. And while it might seem that a PLC would be more cost-effective, keep future needs in mind with the automation order. For example, a touch screen monitor is actually easier to swap out down the road than a manual panel that needs diagnostics and greater work at replacement.

At the planning stage, good communication with the system developer will make the installation go more smoothly for everyone involved — when both parties know not only what is on site and the facility’s climate, but also what’s being integrated with the automation. Communication will ensure return on investment, ultimately protecting equipment assets down the line.

Installation interests

Good housekeeping should start with the installation. For purposes of smoother installation, and easier inspections over time, make sure the contractor installs and clearly labels the cables. It might take a little longer to neatly lay in all the cables, but it will pay off in the long run if a need arises for troubleshooting.

Today’s sensors are actually very rugged sensing elements. Different sensors are made for different environments, so as long as the designer/manufacturer knows environmental parameters, the system’s sensors should be designed to take the daily abuse dealt out in any given setting. But no matter how rugged a sensor might be, misuse or abuse will cause failure. Something as simple as a hose rubbing a sensor limit switch will ultimately ruin the sensor. Make sure that, during the installation, sensors are placed in an area that will minimize their contact with the environment. It’s understandable that there are some limits to where sensors actually can be placed. An enclosure for them is the best scenario.

Regular maintenance tips

Daily:  As part of a pre-startup routine, verify that the system is reading and providing information; verify that there are no issues between the sensor and the HMI system — i.e. the computer. Basically, any parameter that might cause the machine to shut down should be checked daily within the system — such as lubricant pressure.

Weekly:  Monitor trending. For example if a bearing temperature is rising, it could signal impending failure. Schedule the maintenance before it causes unplanned downtime. Check for dust buildup, corrosion, and other environmental effects on sensors, controls, and equipment units. If the controls and/or sensors are dirty, clean them.

Monthly:  If control enclosures are exposed to any sort of climate extremes, whether heat, cold, or moisture, do a thorough visual inspection on a monthly basis. And keep general housekeeping in mind as time goes on. Protect all cables and lines not only from dusty environments, but also other equipment. For instance, dripping oil on cable labels will disintegrate the labels and render them unreadable when it comes to troubleshooting or maintenance needs.

Annually:  Every installation is different because every application is different. From the size of the material to be processed, to the environmental and climate conditions, all of these parameters work together to create different conditions for the automation system that helps to run the processing equipment. Most manufacturers recommend an annual preventive maintenance visit for automation systems. During a maintenance visit, the specialist will test system functionality, revise configurations if necessary, adjust and calibrate the system, update the software, and provide additional training for the daily system users.

Final thoughts

Producers are adding automation to their operations — not only with new plants, but also as part of retrofitting existing operations. Automation can provide anything from basic machine control to a high level of process control to maintenance and service control. Automated packages help improve the bottom line through real-time monitoring that maximizes productivity and reduces downtime by tracking performance, scheduling maintenance, and troubleshooting problems. It is important that the automation package is installed with the correct specifications for climate and environmental protection; and by following recommended system checks, operations can ensure their systems function properly for the long-term with minimal problems.

Garrett Forkner is product support engineer for FLSmidth Excel. He has a bachelor’s degree in mechanical engineering with six years of experience in automation and controls. He can be contacted via e-mail at garrett.forkner@flsmidth.com. Andrew Rieland is manager of electrical design for FLSmidth Inc. He has a bachelor’s degree in electrical engineering, a master’s in business administration, and seven years of experience in machine control systems. He can be contacted via e-mail at andrew.rieland@flsmidth.com.

by Kent Pellegrini

At the risk of stating the obvious, few hydraulic excavators are exposed to a working environment more hostile than that of machines employed at a quarry face. The weight and abrasiveness of the rock accelerate wear, and its unyielding nature abuses digging structures and imposes immense twisting forces in the undercarriage when tracks ride up on fallen debris.

So to begin, the first rule of preventive maintenance for these machines is the one we’ve heard so often that the advice often is ignored: visual inspection. In a perfect world, checking fluid levels, looking for leaks, checking for abnormal undercarriage wear, checking track tension, and inspecting for impact damage to the boom, stick, bucket linkage, cylinders, hoses, and steel tubes would be done at least at the beginning of each shift — and any potentially threatening conditions would be resolved immediately.

Leak inspection should include the cooling system, engine oil/fuel, hydraulic system, (cylinders, hose connections, and pumps), swing system, final drives, and track rollers. Some manufacturers also may suggest draining water from the fuel/water separator and fuel tank (in an appropriate manner), cleaning the air-intake pre-cleaner, and inspecting the radiator and coolers for dust accumulation at 10-hour intervals.

GET, welding cautions, and grease

At the top of the visual-inspection list, of course, is the bucket and its ground-engaging tools (GET). Check that retaining hardware for bucket teeth and edge-protector systems is tight and in workable condition. And of utmost importance, keep a close eye on GET wear to avoid jeopardizing the bucket’s structure. In some instances, bucket-tooth positions can be switched to promote even wear.

Although most manufacturers don’t advise the practice, some machine owners “hard-face” GET (add weld beads to wearing surfaces) or add wear plates on buckets to extend life. If this is done, keep three cautions in mind: weight added to the bucket may affect machine balance; bucket base metal may be compromised by welding heat; and improper welding can, potentially, jeopardize electronic controls and bearings. Consult with your manufacturer about minimizing welding hazards.

Given the severity of quarry-face operation, keeping the loading mechanism (boom, stick, and bucket) properly lubricated is essential — at proper intervals and with the proper amount and type of grease. Follow the manufacturer’s recommendations closely, and remember that grease recommendations may change with ambient temperature. Don’t overfill the reservoir of an automatic lubrication system (added pressure could pop the cover) and use care not to introduce debris; blocked lines are disastrous.

Coolant, oils, and predictive repair

The cooling system is likely the least understood and most often ignored system in your excavator. Whether your machine uses “fully formulated” antifreeze (with conventional additives), or an “extended-life” type (with organic-acid additives), check the coolant’s freeze point, clarity, and color at each oil-change. If rust or sediment is present, or if the color is suspect (an indication that antifreeze types have been mixed), ask your dealer’s advice, or that of a fluid-analysis lab, about remedial options.

In general, replenish any cooling system with a 50/50 mix of the correct antifreeze and deionized (mineral-free) water. Remember, too, that fully formulated coolant requires periodic addition of a nitrite-containing supplemental cooling additive (SCA) to protect the engine’s cylinder liners from cavitation.

Like proper coolant care, consistent analysis of the quarry machine’s various oil-filled compartments is essential. Over time, oil-analysis results can help establish optimal drain intervals for various fluids and can provide wear-trend information that allows timely, informed decisions about scheduled component replacement or before-failure repair. Nothing wrecks production schedules and budgets quite as effectively as a good, out-of-the-blue, catastrophic failure.

Also, simple precautions when working with an excavator’s fluid systems can help avoid problems, such as discarding the first small volume of fluid drawn from a sampling tap to clear residual debris, and properly tightening filters. (Caterpillar prints tightening procedures on each filter to ensure its proper performance.)

Electronic assistance

Among the most potentially useful preventive-maintenance tools available today are wireless information systems that communicate pertinent machine information to the machine owner. Caterpillar’s system, Product Link, for example, is standard equipment on all its new excavators and reports information on three levels: Asset Watch (reporting such data as location and hours); Maintenance Watch (allowing maintenance scheduling and history); and Health Watch (reporting fault codes, event codes, and fuel consumption).

The point is this: If your machine is equipped with such a system (you can also usually retrofit a system to an existing machine), consider subscribing to its reporting capability at the highest level. This level likely will provide immediate alerts (via cell-phone text or e-mail) about machine abnormalities (out-of-range temperatures or pressures, for instance) or machine “events” that could negatively affect the machine’s heath (such as poor operating techniques).

If the machine owner acts on this real-time information, potentially serious problems can be averted — which is the ultimate goal of preventive maintenance.

Kent Pellegrini joined Caterpillar in 2001 and currently is the marketing manager and a product application specialist for hydraulic excavators. He previously held the position of product marketing manager for skid-steer loaders and multi-terrain loaders.

Excavator Rx

Check items on this checklist once every 10 hours of operation to keep your excavator in peak condition.

· Check coolant level;

· Check engine-oil level;

· Check hydraulic-oil level;

· Drain water from fuel separator/tank;

· Test indicators and gauges;

· Inspect undercarriage and track adjustment;

· Inspect digging structures (boom/stick/bucket);

· Lubricate boom/stick/bucket linkages;

· Inspect seat belt; and

· Test travel alarm.