Canada's “Rock to Road” Magazine

December 2006 Issue

• Asphalt plant mobility aids storm damage repair
• Tracked screen aids contractor in clean up
• Major roadbuilding product launch by Ingersoll Rand
• Belt fasteners and cleaners combine to conveyo profits
• Regularly scheduled oil analysis saves time and money

For a copy of the issue that contains these articles with colour photos, click here.

Asphalt plant mobility aids storm damage repair

By Larry Trojak and Andy Bateman, Engineering Editor

     A Newfoundland paving contractor’s new portable asphalt plant has been put to good use repairing the province’s storm damaged roads.

     While many were preoccupied with the damage caused by Hurricanes Katrina and Rita last year, parts of Atlantic Canada were enduring climate related hardships of their own. Rain came to Newfoundland in the fall of 2005 with a vengeance, dumping nearly 200 mm of precipitation on some areas in a 24-hour period. Damage in some regions such as Stephenville on the island’s west coast was particularly heavy, but road and culvert washouts were commonplace throughout the province and resulted in hundreds of kilometres of infrastructure damage. Provincial Paving Ltd., one of the firms heading up the subsequent repaving effort, credits the speed and portability of its new portable asphalt plant with helping it to meet an aggressive 2006 road repair and paving schedule.
     Established in 1990 by owners Levi House and Leon Samson, St. John’s-headquartered Provincial Paving has grown steadily to become one of the island’s five major players in highway-related asphalt paving. Even without the “assistance” from Mother Nature, the company manages to maintain a full schedule of roughly eight major projects and $10 million in sales a year. According to Bill Casey, the firm’s superintendent, however, that workload was increased this year by essential storm-related remediation work. “We generally have three or four crews at work at once, each working in advance of the other,” Casey explains. “So, while we are wrapping up a paving project, we already have a crew at the next site preparing it by doing the ditching, the culvert work, and any rock excavation that needs to be done, as well as by starting up the crushing operation. As the name of our company might imply, we tackle projects throughout the province, and that has certainly held true this year — we’ve done work in almost every part of the island. The rains were particularly bad out west but many other parts were hard hit as well, so we’ve been on the move almost non-stop.” In addition to its regular paving work, Provincial also handles upgrading projects and culvert work, as well as projects for individual municipalities and the province’s Department of Works, Services & Transportation.
     Provincial’s success is largely dependent on operational flexibility and mobility. At one point in the recent past, says Casey, that advantage was being hampered by the cumbersome nature of the firm’s asphalt batch plant. “Our previous plant was a bit outdated, so we weren’t getting the overall production we would have liked. More importantly, however, it used to take us five to six days to move it from site to site and that, more than anything, really held us back. A few years ago we decided a change was needed and we made it.” After much research, Provincial opted to replace the existing batch plant with an ADM Roadbuilder 160 plant, choosing a configuration that included a control room, four cold-feed bins, a weigh conveyor, a 45-tonne capacity self-erecting silo and an asphalt tank.
     The new plant provided Provincial with a new level of portability, as each of its components is designed with set up and tear down in mind. “The difference between the two plants was amazing,” says Casey. “In the past, a move was a major undertaking — today, that same move can be done in two to three days. In fact, on our last move, we started taking down the plant on Thursday and we were paving again early on Saturday. When you consider how often we move from location to location, those days gained from each move can add up. It’s really made a big difference for us.”
     In common with their counterparts elsewhere in Canada, Newfoundland-based asphalt paving firms face the challenge of finding and processing good sources of aggregate for use by the asphalt plant. Provincial meets this challenge by vertical integration. “We have a Cedarapids MVP 380 cone crusher feeding a 30x42 jaw crusher which allows us to make everything from plant mix to all the Class B we need,” says Casey. “At times, having that full compliment of equipment can be an issue in itself. A case in point was a site we worked near Baie Verte, in the northern part of the province. It was extremely limited in terms of space, so getting trucks in and out at peak times was sometimes a headache. Fortunately, the new asphalt plant has a fairly small footprint so once we tore down the crushing plant and moved it on to the next location, we were fine.”
     The new plant has also delivered good productivity as well as mobility. Casey reports that its rated capacity of 145 tonnes/h has been regularly met or exceeded. Typical daily production has been about 1300 tonnes, rising to over 1800 tonnes on longer summer days. Factors contributing to this good productivity are said to include fast and easy mix design changes using the system’s touch-screen controls in addition to good after sales support, despite the company’s relatively remote location.
     Manufacturer’s data states that the Roadbuilder plant’s parallel-flow design maximizes drying as it moves the moisture-laden aggregate in a rotating, veiled pattern away from the flame produced by its fuel efficient Hauck burner. Like other ADM plants, the Roadbuilder is designed to operate on multiple fuels and any pre-specified electricity supply. In operation, the Roadbuilder typically requires one plant operator and one loader operator. The overall plant design focuses on a simple, dependable, easy-to-operate and maintain, truly portable asphalt plant with a durable design that lets contractors be competitive on both large and small projects. Due to its reported overall fuel efficiency and low maintenance, the Roadbuilder is said to produce asphalt at the lowest cost per tonne of any plant its size.
     Provincial’s last move for this year had it heading to the Burin Peninsula on the island’s southeast coast. Casey notes that the firm wrapped up several projects in that area before the winter and will resume operation in April or May 2007. “We completed 8 km of road repair on the peninsula that involved about 12 000 tonnes of asphalt,” he says. “That and one more small project in nearby Marysville wrapped things up for us. This has been a very full year that saw us generating nearly 45 000 tonnes of asphalt over the paving season and things look equally busy for the next few years as well.”

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Tracked screen aids contractor in clean up

A new tracked screen has helped a demolition contractor reclaim a well-known brownfield site in Toronto.

By Andy Bateman, Engineering Editor

     The Inglis Lands just west of downtown Toronto have a long and varied industrial history and are a familiar if unbeautiful landmark to users of the city’s Gardiner Expressway. For over a century, the site was utilised to manufacture products ranging from weapons to washing machines and has been derelict for over fifteen years. As part of the city’s plan to redevelop the Garrison Common area, site clearance is now well advanced to make way for the site’s redevelopment. To quote City of Toronto By-Law No. 540-2004, “the area as a whole is experiencing rapid redevelopment and growth, particularly the conversion of underutilized industrial and institutional lands to more intense light industrial and residential uses.” (See sidebar).
     Priestly Demolition Inc., now in its fourth year on site, has played an essential role in the overall remediation process. Priestly’s work has consisted mostly of the demolition of numerous underground concrete and brick structures, together with the excavation and removal of their respective foundations, underground services and old site fill material. Some locations have required specialist reengineering such as the replacement of excavated material near existing buildings with lean mix concrete. In all locations however, excavated material is tested according to a site protocol for the presence of heavy metals, hydrocarbons and other potential contaminants in recognition of the site’s industrial legacy. After testing, material cleared for reuse is screened to produce a manageable graded fill, mostly for use off site.
   To help with the massive clean up job, Priestly acquired a tracked mounted screen in fall 2005. The screen’s job looks deceptively simple; produce screened fill from a wet and variable mixture of broken concrete, rebar, broken brick and clay soil, or rather clay lumps, thanks to some of the wettest weather on record. Producers who have attempted the screening of such material will know it is easier said than done.
    During Aggregates & Roadbuilding’s recent site visit, screen feed material was first gathered into a stockpile by a Komatsu PC400LC excavator. The PC400LC then provided a steady flow of material to the Extec E7 track mounted screen which separated the feed into 25 mm minus product and oversize material. The product was stockpiled, while the oversize was spread by a Dresser TD15 dozer and allowed to dry for later rescreening. Priestly’s Aivars Koskins (Ivis) reports reasonable screen productivity even in these conditions, adding that product separation is significantly more efficient in drier conditions and does not require the rescreening step.
   Extec describes its new E7 tracked screen as a heavy-duty track mounted self-propelled open flow screening and stockpiling system that has been purpose built for the recycling and quarrying markets. Listed applications include the screening of heavy overburden at the quarry face, material pre-screening and scalping prior to crushing, the recycling of construction and landfill waste, as well as the separation of “sticky” aggregate. The E7’s design includes a heavy-duty hopper, adjusted for length and loading height, with a capacity up to 10m3. It also has a double plated apron plate feeder, heavy - duty screen box with uniquely high throw and high vibration with an adjustable angle of incline ranging from 10-22°. Punched plate, heavy duty mesh, rock fingers or grizzly bars can be fitted to the top deck, while heavy duty mesh or fingers can be fitted to the bottom deck. The design provides a large free flow area from the hopper onto the screen box and also from the screen decks to the stockpiling conveyors. The unit’s rear conveyor handling large sized products is supported by an impact bed to prevent roll-back or lateral movement of material. The E7 has a heavy duty crusher-type chassis.
     Priestly Demolition Inc. is based in Aurora Ontario.

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Major roadbuilding product launch by Ingersoll Rand
Ingersoll Rand introduced several new products to the North American market at a recent major product launch which was attended by Aggregates & Roadbuilding.
    Ingersoll Rand’s new offerings include two milling machines, three pavers and five compactors, all launched during the “Red Carpet Premiere” event held at the company’s Shippensburg, PA facility. The week-long event provided both live and static demonstrations as well as product information sessions to owner, contractor and media groups. Additional new models are promised by the company, the result of an ongoing initiative to maximise technology exchange and product development across its worldwide operations.

Milling Machines
    Ingersoll Rand has entered the milling market with the global introduction of two new milling machines, designated the MW-500 and the MT-2000.
    The MW-500 is a four-wheel, utility-class machine offering an extremely tight cutting radius of 175 mm with a standard cutting width of approximately 500 mm and a maximum cutting depth of 210 mm. Developed and engineered at the Ingersoll Rand ABG facility in Hameln, Germany, where the new machine will be manufactured, this rear-loading machine is designed for patching, trenching and shoulder milling applications.
    A 125 hp Deutz diesel engine powers the MW-500, with power transferred via an automatically tensioned belt drive. The control panel brings advanced technology to this class of milling machine and includes a brightly illuminated display and back-lit membrane switches for low light operations.
    The MT-2000 is Ingersoll Rand’s flagship model in North America Engineered, developed and built at the company’s Shippensburg facility, this four-track, front-load, half-lane milling machine is powered by a 600-hp Tier 3 Cummins engine. The MT-2000 is, according to the company, the first machine to offer three distinct drum cutting speeds; 1400 rpm deep-cut power bulge; 1800 rpm, standard cutting speed and 2400 rpm, shallow cutting efficiency
    The deep-cut power bulge feature provides higher torque at lower engine rpm to power through tough material or deep-cut applications. The high-speed selection is for maximum speed on shallow cutting depths. The standard cutting speed is used to provide maximum horsepower and efficiency at normal cutting depths. The MT-2000 can run both 2000 mm and 2185 mm drums, while the drum and housing are easily removed together to reduce time and complexity during interchange. With five steering modes, the MT-2000 is reportedly the most manoeuvrable machine in its class.
    Ingersoll Rand plans a full product range of six milling machines with cutting widths from 508 mm to 4.27 m, power from 125hp to 1000 hp and operating weights from 8.6 tonnes to 45.4 tonnes.

Pavers
    The PF-6110 track-mounted paver and the PF-6160 and PF-6170 wheel-mounted pavers are part of a new highway class paver series utilising global technology to provide increased paving performance. A wide selection of Ingersoll Rand screeds is available for these pavers, including the new Omni Series.
    Numerous features have been introduced on the PF-6110 to provide greater control of material flow. The auger system is now independent of the conveyor system, while each of the two auger and conveyor drives uses sonic sensors for more precise handling of material. The conveyor system’s chains are automatically tensioned for proper performance and less downtime. Hopper capacity for the series is 13.1 tonnes, giving each paver a practical production rate of 744 tonnes per hour. A 205 hp (153 kW) Cummins Tier 3 engine powers each paver in the series. The PF-6110 has a paving speed of 74.9 m/min and a travel speed of 18.3 km/h. The operator station features a new layout and a digital display, with the display providing the operator with onboard diagnostic capabilities in four languages.
    A technically advanced, hydrostatic direct-traction drive system on the paver eliminates 70 per cent of all mechanical drive train components to reduce maintenance costs. The continuous and flexible rubber tracks on the PF-6110 have larger, oscillating bogies that provide optimal ground contact and traction. An integral Blaw-Kote release agent spray system with push-button operation facilitates track cleaning and maintenance.
    The PF-6110 paver has a screed width of 3 m and a maximum paving width of 7.92 m. PF-6160 and PF-6170
    Like the PF-6110 track-mounted paver, Ingersoll Rand’s PF-6160 and PF-6170 wheel mounted pavers incorporate a number of new features to provide contractors with more options in material flow. The auger system is now independent of the conveyor system. Each of the two auger and conveyor drives uses sonic sensors for more precise handling of material. The conveyor system has chains that are automatically tensioned for proper performance and less downtime. The conveyor chain cover is self cleaning for easier maintenance. Reversible augers and conveyors are optional equipment.
    Each paver is powered by a 205-hp Cummins Tier 3 engine. The PF-6160 and PF-6170 pavers have a paving speed of 89.3 m/min and a traveling speed of 19.3 km/h.
The PF-6160 is designed without front-wheel assist, while the PF-6170 is available with two-wheel assist or optional four-wheel assist.
    The PF-6160 and PF-6170 pavers maintain uniform wheel-loading through a patented front-wheel suspension design. Hydraulic bogie cylinders provide a uniform load on all wheels for higher ground clearance, maximum traction and less wear and tear on the paver. Both pavers have a screed width of 3 m and a maximum paving width of 7.92 m.

Compactors
     New for 2007 in Ingersoll Rand’s compactor range are two machines in the 2.5 tonnes class and three machines in the 9 tonnes class.
     The 2.5 tonnes machines, designated DD-22 and DD-24, are vibratory asphalt compactors designed for optimum compaction of complex materials. Operating weights for the DD-22 DD-24 are 2450 kg and 2600 kg respectively with drum widths of 1000 mm and 1200 mm. These units feature dual amplitude drums, while high frequency (over 4,000 vpm) allows for maximum rolling speeds.
     Ingersoll Rand’s three new vibratory asphalt compactors in the 9 tonnes class are designated DD-92HF, DD-98HF and DD-98HFA.
     Features common to these machines include a 130 Hp 4-cyl Cummins Tier III diesel engine, “SMART” drum technology, rotating operator’s pedestal for enhanced visibility, maximum drum visibility due to leg design and large diameter drums to minimize mat disruption.
     SMART drum technology includes automatic vibration engagement that turns vibration on or off at a set minimum speed. The SMART start drum vibration system initiates vibration with the lead drum three seconds prior to trailing drum for compaction efficiency. The system also matches eccentric rotation to travel direction to prevent a “wave”. Automatic speed control matches machine speed to vibration frequency to maintain ideal spacing, as shown by a patented impact spacing meter. With the system’s vibration/amplitude matching, frequency is optimized depending on amplitude selection. The high frequency design of these machines allows for faster rolling speeds to keep up with the paver while assisting in reaching target densities quicker by compacting in higher temperature zones.
     The DD-92HF is a two-amplitude compactor with a vibration frequency range of 3000 – 4200 vpm. At 4200 vpm, the DD-92HF offers the industry’s fastest rolling speed with vibration, according to Ingersoll Rand. A centrifugal force of 16 112 kg provides maximum compaction on thick lift applications.
     The DD-98HF is an eight-amplitude, compactor with a vibration frequency of 3804 vpm. Its exclusive eight-amplitude technology allows for fine-tuning of drum energy for differing material and changing conditions. The high-frequency vibration offers faster rolling speeds for increased production, while a centrifugal force of 18 716 kg provides maximum compaction effort.
     The DD-98HFA is described as the ultimate solution for any compaction application. This machine combines the frequency range of the DD-92HF with the eight-amplitude technology of the DD-98HF to control any mix.

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Belt fasteners and cleaners combine to convey profits

Effective interfacing of belt fasteners and cleaners can boost performance and profits.
    Conveyor belts are a lifeline for effective, profitable aggregate production. The equation that governs their operation is simple. Peak efficiency brings productivity and profit. Breakdowns bring downtime, and when they occur, profits and productivity suffer.
   While belt cleaning systems alone will not assure trouble free handling, they do contribute to successful outcomes and on-going operations. Comprised of belt fasteners, belt cleaners and other accessories, belt conveyors serve a single focus – to maintain or increase production figures. Because each of these components serves distinctly different duties, they must be selected carefully to operate harmoniously and achieve peak efficiency.
    At the outset, careful consideration must be given in selecting cleaners and fasteners that will work together effectively. The same holds true for belt selection and the development of routine and specialized maintenance procedures for maximum effectiveness.
    Effective belt conveyor maintenance has two key goals…preventing surprise belt failures, and keeping repair downtime to a minimum. While no part of the conveyor system is unimportant, belt splicing is among the most critical parts. First, it’s one of the few components that constantly takes heavy abrasive wear. Second, a failed splice not only stops the material, it drops material – sometimes where the cleanup is worse than the repair.

Mechanical or vulcanized
    Effective combinations of fasteners and cleaners enable mechanical fasteners to serve as a suitable alternative to vulcanization. Mechanical belt splicing has been gaining favour for decades as it continues to prove – and improve – its reliability, while also offering lower costs, quicker installation and easier visual monitoring to prevent surprise failures.
    Mechanical fasteners are recognized as an efficient method of getting failed belts running as soon as possible. They can be installed in a fraction of the time required for vulcanizing and are proven in high-tension applications up to 2000 PIW (350 kN/m). Plus, mechanical fasteners have been used successfully worldwide in aggregate applications since the 1940’s.
    For instance, to vulcanize a 1200 mm wide belt can take from 6 to 8 hours depending on conditions. And that doesn’t include the time lost waiting for the vulcanizers to reach the site and set up their equipment. Materials and labour will cost several thousand dollars and the result can steal about 2500 mm of belting out of take-up reserve. By contrast, a belt the same size can be mechanically spliced in less than an hour. An on-site belt crew using simple tools – often for less then $100 in material, can accomplish the repair. Plus a mechanical fastener repair sacrifices only a few inches of belt.
    Once installed, mechanical fasteners allow visual inspection for wear and damage, which is helpful in preventative maintenance programs based on planned downtime. By comparison, vulcanized splice deterioration or a vulcanized splice installed incorrectly will not be visible in its early stages. This may result in catastrophic belt failure if not caught in time. Vulcanizing also works best on new belting. On older, worn belts – where most emergency splicing is done – vulcanizing often becomes more difficult to do properly, and is less reliable than mechanical splices.

Working together
    Proper interface of cleaner and fasteners also improves belt-conveying performance and prolongs the life of the belt. The performance of belt cleaners adds strongly to the cost effective operation of the conveyor system. After getting the mechanical selection and installation process of the cleaners right, the relationship between belt cleaners, splices, and maintenance then becomes an important factor for the on-going means of maximizing conveyor belt productivity. Component selection involves knowledge of the composition of the fasteners, the cleaners and the belt itself. And there are numerous fasteners, cleaner designs and types of blades to choose from.
     For example, fasteners with “scalloped edges” feature concave, scalloped shaped edges, which allow the fastener plate ends to embed deeper into the belt with less effort, while reducing the splice height. Reducing the splice profile allows belt cleaners to ramp up and over the plates easily without hard edge impact, However, belt splices that sit above the normal height of the belt’s top cover can be picked up by the cleaner tips causing inefficient belt cleaning and will increase the risk of damaging the belt, the splice, or the cleaner.
    In addition, the problems encountered between fasteners and cleaners can be avoided by the simple means of countersinking – removing a strip of rubber top cover to lower the fastener plates below the surface of the belt. On heavy top cover belts, countersinking positions the fasteners closer to the belt carcass. Additionally, this creates synergy between the belt and the mechanical fastener, at the same time reducing the prospects for chips or damage to the cleaner blade.
    From a cleaner standpoint, belt cleaners work most effectively in a systems approach. Multiple types of belt cleaners may make-up a single system; starting with a primary or pre-cleaner mounted at the head pulley where carryback is most effectively removed yet easily kept in the process stream. Secondary cleaners are placed anywhere along the conveyor line to remove fine sticky materials from the belt. If these materials are not removed from the belt they can build-up on return idlers and rollers causing belts to mistrack and component failure, which can result in further damage to pulley lagging and belt ends.
     Belt cleaners are available in many forms and each cleaner functions differently to remove product from the belt. Although most cleaners can be effective for a short time, the lasting effects will vary based on several factors.
     First and foremost, correct installation is the key to belt cleaner performance. If a cleaner is not installed properly, it has failed before it begins. Once belt cleaners are properly installed constant blade-to-belt contact must be maintained for the cleaner to perform at peak efficiency.
    Tensioning is conceivably the most important component in a belt cleaning system; cleaners with proper tensioning ensure that the blade maintains constant blade-to-belt contact without putting excessive pressure on the belt. Cleaners with spring tensioning systems allow mechanical fasteners to pass easily under the blades by momentarily releasing the cleaner blade when the splice passes underneath.

Degree of freedom
     Also deserving consideration are the degrees of freedom or relief points stemming from the interaction of the belt and the cleaner. Interaction involving the belt, its fasteners and the cleaner creates considerable kinetic energy. This energy is received in short intervals when the splice hits the cleaners. Proper cleaner fastener interface requires receiving this energy without damaging the splice and or the cleaner. Multiple tensioning elements, providing energy absorption/relief, are needed to store and dissipate this energy while keeping the cleaner blades in contact with the belt. Applications with higher speeds and loading rates necessitate cleaners with multiple tensioning elements.
    There are cleaners which incorporate four tensioning elements in their design. These four elements provide an action that allows the cleaner tip to maintain contact with the belt and mechanical fastener, and at the same time, dissipate the harmful impact energy rather than have the energy cause damage to the components – belts, mechanical fastener, or cleaner.
     Properly selected, installed and maintained, the combination of mechanical fasteners and cleaners form an effective working team. While their roles differ, they share a common purpose, one that keeps belt conveyors moving toward greater productivity and profit.

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Regularly scheduled oil analysis is an excellent maintenance tool
   The use of regular oil analysis and testing is an effective and inexpensive predictive maintenance technique that cannot be ignored by the owners and operators of aggregate and roadbuilding equipment. If used on a regular basis, a well planned oil testing program which applies the right test techniques for the appropriate application, will provide a return on investment of 250 per cent or more in terms of providing early warning of impending machinery failure and ongoing condition monitoring of equipment.
   Oil analysis provides the operator with information about:
   • The physical condition of the lubricating oil.
   • The condition of the component or system from which the oil sample was taken.
   Effective oil analysis, properly applied, is the “Blood Test” of industrial machinery and can be used to determine the following conditions:
Proper oil drain intervals
   Measuring changes in viscosity, neutralization number and additive levels can provide accurate information concerning the initial determination of oil drain periods.
Contamination levels
   Dirt, water, acids, fuel and anti-freeze contamination can be accurately measured using the correct oil testing techniques.
Temperature limits
   By monitoring changes in viscosity and total acid number, temperature related problems can be located and subsequently corrected.
Component wear rates
   Measuring the rates of wear on regularly scheduled intervals can determine the ongoing wear rate of any lubricated system. In addition, this testing can warn the operator of impending failure if sudden, large increases in wear rates are reported.
Oxidation & nitration rates:
   Excessively high or low operating temperatures will dramatically affect lubricants and chemical changes in the oil can be determined by monitoring viscosity, total base number, total acid number or by infrared testing.
Types of wear:
   Using a specialized oil testing technique called “ferrography”, various types of wear can be determined.
Warranty claims:
   A regularly scheduled oil analysis program consisting of the right tests for the appropriate equipment can very often substantiate warranty claims if a new machine or component fails prematurely. (The reverse is also true. Oil analysis has often supported an equipment manufacturer or distributors claim that the proper maintenance or oil drain interval were not carried out correctly by the equipment owner prior to a failure).
   Oil samples should be taken when the oil has reached its operating temperature, usually just after a machine has been shut down. This will ensure that any foreign material or contaminant such as water or dirt will remain suspended in the oil.
   In aggregate equipment, dust and rock particle contamination can cause severe damage very quickly. High operating temperatures can also be a factor. As a result, it is important to apply the following oil analysis tests to the applicable machinery. The tests described will provide the minimum information necessary for a sound predictive maintenance program.

Oil analysis of cone and jaw crushers, gear reducers and hydraulic systems
   Samples should be taken on a regular basis of every 250 operating hours (once wear rates and operating condition trends have been established, usually after 4 or 5 sample results, extending oil sample intervals to every 400 - 500 operating hours may be considered. This will depend on operating conditions and oil sump size. If the conditions are extremely dusty and the sump size comparatively small, say up to 10 gallons, continue to use the 250 hour interval).

Minimum recommended tests for cone crushers
    1. Spectrographic wear rates. Keep in mind that large or sharp increases in wear metal levels should be investigated immediately.
    2. Viscosity. Measured in centistokes at both 40û and 100û C. The results can be compared with the appropriate oil specification charts. Any increase in viscosity of over 10 per cent is cause for further investigation.
    3. Water contamination. 50 parts per million or .5 per cent of water is considered to be the maximum allowable level. (The amount of water which is acceptable also depends upon the type of bearings found in the crusher. Cone crushers using bronze bushings may be susceptible to excessive corrosion if too much water is present, particularly if operating temperatures are extremely high).
    4. Large particle contamination levels. Dirt and rock dust particles larger than 7 or 8 microns cannot be monitored by spectrographic metal analysis. This is an inherent limitation of spectrophotometers. Therefore electronic or gravimetric particle counts are highly recommended as part of the oil analysis program used for crushers, gear drives and hydraulic systems on aggregate machinery. In fact, catastrophic failures caused by large particle contamination may be imminent with no corresponding increase in wear metal rates. For this reason, particle counts may be the most important, yet least used oil analysis technique applied by aggregate equipment operators.
    5. Total acid number (TAN). This neutralization number test measures increases in acid levels in lubricants used in gear drive recirculating systems and hydraulic applications. It is an extremely useful test when determining oil change intervals. The rule of thumb for this test is that immediate action must be taken when the TAN doubles. This test can also be used to monitor the oils condition on an ongoing basis.

Engine oil analysis
Diesel engines
     In addition to viscosity, water and wear metals testing, it is recommended that diesel engines be monitored every 250 hours for anti-freeze and fuel leaks and combustion soot levels. Diesel engine combustion is often incomplete due to low temperatures, excessive idling, insufficient air intake or other causes of imbalance in the air/fuel ratio.
     These problems can result in high levels of carbon soot being generated and subsequently suspended in the oil. Excessive levels of soot can inhabit the anti wear additive’s effectiveness and high soot levels are often accompanied by high levels of iron wear in diesel engines.
    For this reason, it is extremely important that soot levels be monitored regularly in diesel engines. It also points out the importance of operating diesel engines that are properly tuned, regularly serviced and never run at idle or unloaded speeds for long periods of time.
     In addition to the tests described above, the total base number of the lubricant may be monitored in diesel engines, in particular when initial oil drain intervals are being determined or if poor quality or high sulfur fuel is being burned. Total base number (TBN) is a measurement of the reserve alkalinity remaining in engine oils and is indicative of the oil’s ability to counteract acid formation (such as that caused by excessive idling or low operating temperatures).
      A low TBN usually means a depleted additive package, particularly the chemicals which make up the detergent/dispersant additive. The rule of thumb is that when the TBN is reduced by one half (1/2 of that of the new oil), action should be taken to drain the oil and determine the cause of the reduction in the TBN.

Natural gas and propane fuelled engines
     Oil used in natural gas and propane fuelled engines are subject to conditions called nitration and/or oxidation. These are chemical reactions within the oil usually associated with extreme operating temperatures (too hot or too cold) and/or incorrect air/fuel ratios.
     Both conditions initially cause the engine oil to thicken prematurely. Oxidation rates increase as engine temperatures increase over 200ûF. Nitration rates on the other hand increase as the operating temperatures decrease and nitration increases rapidly at temperatures below 135ûF. To reduce the possibility of these conditions, engines burning propane or natural gas should be operated at temperatures of about 180û F.
     Continued high viscosity readings on the oil analysis reports may suggest an oxidation or nitration condition. If the premature oil thickening persists, even after the oil has been drained and replaced, it is advisable to have the oil analysis laboratory carry out an infrared test to determine the amount of oil degradation. Frequently, using the wrong oils can cause this problem, but often the cause cannot be corrected and oil drain intervals may have to be shortened in order to prevent long term damage to the engine.

Selecting a laboratory
     Before selecting a laboratory, visit several to determine if they can carry out the tests recommended above. If a lab cannot carry out all of these tests, if you feel uncomfortable with the answers to your questions or if the lab hesitates to provide references, your next step should be obvious; find another laboratory.
     Your oil supplier can also often recommend good quality laboratories and will often assist you with the oil analysis results interpretation. Your best bet, however, is to select a laboratory that is willing (and able) to train your maintenance staff as to the proper interpretation of the oil analysis reports and results.
     A typical oil analysis report must not only report the test results described in this article but must also include a brief report and subsequent recommendations. (see the illustration).
     Once you have selected a laboratory, continue to use its services. Don’t jump from lab to lab because the results will never be consistent due to the many different types of analysis test machines and calibration levels in use. Also insist that where they are specified, the lab uses correct ASTM (American Society of Testing and Materials) testing methods and procedures.
     To conclude, a well planned oil analysis program is an invaluable tool to complement your predictive maintenance program. The capital expense of a series of $30.00 tests is a small price to pay for returns that could amount to thousands of dollars in reduced repair costs, extended machine life, reduced downtime and improved productivity.

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December 2006 issue

Aggregates and Roadbuilding Magazine
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