When it comes to contaminants, hydraulic systems are more sensitive than engines—and dangers lurk everywhere, including human error when changing attachments in the field or when refilling the reservoir. Wear permits the ingress of environmental contaminants and can even create slag or other contaminants internally. And, as some in the industry know, not all hydraulic fluid comes from the manufacturer clean. Whatever the source, ignoring hydraulic contaminants doesn’t make them go away.
“Hydraulics is one of the most neglected areas of heavy equipment,” states Mark Betner, heavy-duty product line manager for Citgo Petroleum Corp. at Houston, TX. Betner confirms the existence of numerous hydraulic performance issues. “The situation goes way back,” he says.
There are several problems, Betner claims. For starters, apparently, hydraulic systems don’t realize they’re on haulers, rendering them incapable of coping with the demands of the dirty environment and tough working conditions. “Trash is not the cleanest stuff in the world; it’s dusty, wet, [commingled] with dirt…” He explains how the rams on a hydraulic cylinder can drag dirt past the seals. It becomes abrasive, wearing down the seals and deteriorating hydraulic valves and pumps.
In addition to the dirty operating environment, vehicles suffer under temperature ranges. “North of the Mason-Dixon line,” Betner begins, “[a collection vehicle] has to function from subzero to 100-plus degrees. In cold weather, the system is sluggish. When it’s air-binding, it won’t actuate; it won’t operate properly.” On the other hand, in the South, hydraulic systems get hot, slow down and lose work efficiency—particularly if they are worked continuously under high loads. They get “spongy,” he explains, which causes a loss of productivity and could lead to leakage. That can initiate a vicious cycle if operators add excessive oil in an attempt to alleviate the issue.
The need for a solution is not being fully addressed, Betner believes—even by equipment manufacturers. That’s why Citgo has launched an initiative to educate operators about preventative maintenance. “What you don’t know about hydraulics can hurt you.” The best thing you can do, he adds, is to begin a fluid-monitoring program and select the right product. “Fluid-monitoring programs provide information to help reduce component replacement and leakage.” A sensible program, when adhered to, saves parts, labor, downtime, and fluid cost.
Get With the Program
The number-one cause of problems, Betner believes, is that hydraulic fluid is too dirty. Dirty oil causes wear in pumps and valves, as well as seal damage. He refers to a Citgo customer with a fleet in Chicago that lost 400 hydraulic components in one year because the oil was three times dirtier than it should be. The hydraulics manufacturer recommended talking to a fluid provider. One year later, now on a fluid-monitoring program with different intervals in the filter schedule, the same fleet has lost only two hydraulic pump cartridges.
While keeping fluids clean is imperative, Betner recognizes that numerous technical developments are complicating routine maintenance activities. That’s why getting on a fluid-monitoring program is beneficial: It allows the operator or fleet supervisor an opportunity to sit down with someone who can make recommendations and investigate better practices.
“The push is to keep oil cleaner,” acknowledges Dan Schultz, manager of directly marketed accounts for Schroeder Industries LLC in Leetsdale, PA. “Cleaner oil lasts longer, and extending oil drains is a cost savings. With the cost of oil and fuel, that’s important now more than ever.” In addition, he says, it’s important to “get people thinking about cleanliness” now in preparation for the switch to piston pumps, which must run cleaner oil. “It’s not standard practice, but in Los Angeles, for instance, you can’t run diesel-powered municipal vehicles; they must be natural gas or LP.”
On Automatic
Joe Van Thuyne, direct sales manager for Lincoln Industrial Corp., realizes that most of the St. Louis, MO–based company’s customer base, which centers around municipalities and private hauling companies, is under the gun to reduce maintenance costs, as well as parts and labor costs, while at the same time keeping the equipment up and running. He also knows there’s currently a shortage of qualified mechanics. To combat those issues and more, he suggests Lincoln’s automatic lubrication systems, all of which direct precise amounts of grease or oil from a centralized pump station through a single supply line (or pressurized two-line system) to individual externally adjustable injectors that deliver precise amounts of grease or oil to bearings or other lubrication points.
There are many benefits provided by the systems, which are easy to install and maintain on both new and older trucks. They require less labor; they result in less road failure and less downtime; and the costs are equal to or less than manual greasing over a nine- to 18-month period ($3,000–$5,000), with the long-term bonus of reduced maintenance costs, because greasing every hour doubles or quadruples the life of parts. “Side-arms require daily manual lube,” he says. “Rear- and front-load require weekly/biweekly lube. That’s 15 to 50 points to grease daily or weekly—it’s a sizeable amount of money when you do the math.” His math is based on a cost of $20 to $80 per grease job.
But according to Van Thuyne, the biggest plus of automatic grease systems eliminating manual intervals translates into savings of a different kind: safety. “With a front-loader, you have to use a climbing gate to reach the 6-foot front of the truck. Accidents affect profitability. You have to consider the insurance aspect of a manual lube.”
Another cost advantage comes from eliminating employee time dedicated to changing oil and maintaining records. Because the pump is wired to the ignition, it records the run time at intervals and distributes a small amount of lube to all the points while the truck is running. Furthermore, the automated process typically uses 25% less grease than technicians use while manually changing oil, for even greater cost savings.
Vogel Lubrication Inc., based in Plymouth, MI, offers two types of automatic systems: a single line and a progressive system. There’s a cost advantage with the single line, says Jason Bendon. The basics for both are the same: an electrically operated gear pump activated by an electronic control unit delivers grease through a mainline to piston distributors, which then deliver lubricant to up to 150 lube points.
With its exclusive post-lubrication technology, Vogel builds on the basics. Lubricant isn’t delivered while the pump is running. It’s not delivered at all “if a point was fully overloaded,” Bendon explains. In that situation, “the pump waits for the point to become unloaded, so you don’t miss a cycle. It won’t create fault with system shutdown; it remains in idle mode.”
Other Vogel advantages include an easy-to-install, quick-disconnect system that replaces nuts and ferrules. Resistant to dirt because of a triple seal, Bendon estimates the systems save five fittings and reduce maintenance time and costs. A user-friendly monitoring package tracks lube cycles.
“Twenty out of 35 trucks get lubricated well; the others get skipped,” Bendon says. That risks bearing life and bushing life: “You don’t want metal-to-metal contact.” By using an automatic lubrication system that applies a small amount of grease at shorter intervals, operators can obtain optimal lubrication, decrease downtime, and increase component wear 400%.
The key, Bendon says, is installation. “If it’s not done right, it’s another maintenance issue.” However, Van Thuyne reports greater acceptance of automatic lubrication systems in the waste hauling industry. “All you do is refill the reservoir. For regular service intervals, you check the hydraulics, et cetera, and do a visual inspection of the lines to lube points. In most cases, maintenance of the lines is minimal; there’s a protective wrap on them.”
Long used on side-, front- and rear-loaders, the system is now also being used on compactors, tractor and trailer systems in refuse markets, sorting equipment at recycling plants, and street sweepers, he says. Van Thuyne attributes that, in part, to the need to minimize downtime. “If a point fails, you have to repair it. Meanwhile, the route still has to be serviced—but no fleet has a spare truck to cover, so it’s important to keep on top of your lubrication needs and make sure your oil is clean.”
Filtering Information
However, keeping oil clean doesn’t end with a focus on fluids. Filtration plays an important part. “Filtration goes beyond the pump,” Schultz notes. “The level of filtration we’re targeting is in the 3-micron range.” That’s down significantly from the previous target of 10 microns.
As Schroeder continues to test synthetic element sizes, it uses micron ratings to determine which will keep oil cleaner. One class makes a big difference. “We’re in the 4-, 6-, or 14-micron range,” Schultz says. For comparison, he points out that 4 microns is the size of a red blood cell and 22 microns is the size of a white blood cell.
Micron ratings will continue to be a focus, as Van Thuyne notes, because the government is changing requirements for emissions standards. “That challenges maintenance due to the increased requirements for particulate filters.”
“We’re seeing a change in the industry,” Schultz reflects. “We’re replacing a large amount of 10 and 25 paper with synthetic media, which lasts 2.25 times longer than 10-micron paper.” He explains that 10 paper compares to 25 paper with finer filtration, but says they may have to stay with 10 and 25 for use in older trucks.
Good filtration has a lot to do with valving to achieve the tightest clearances in the system, Schultz explains. “Tight tolerances reduce leakage [and] reduce heat.” However, tighter tolerances need more protection because they render systems more sensitive to smaller particles.
That demands higher filtration, which in turn drives development—the core of business for Donaldson Co. of Minneapolis, MN, a manufacturer of filtration systems and parts. “We’re always improving our media for better pressure drop,” states Matt Stein, hydraulics product manager.
That’s because good filtration also depends on the right media. Donaldson Co. uses mainly synthetic media. “It has the most value,” Stein says. He points out that the company uses a broad range of media when cost is an issue. But synthetic media have good pressure characteristics, he says, and are durable for extended service intervals.
Donaldson’s breakthrough filter medium, Synteq XP, was recently introduced. Using a resin-free bonding technique, it enhances engine and component protection, features lower operating pressure drop, adds to longer filter life (two to three times that of traditional cellulose filter media), and has higher filtration efficiency. “Hydraulics company manufacturers have standards for protection they want to see,” Stein cites. “We tend to get to higher efficiency levels; we’re able to remove 5 microns and still maintain capacity.”
Also new on the market is the next generation of Duramax, the company’s highly rated spin-on-style filter typically used in return-line positions. Easy to service, the Duramax is well suited for duplex circuits and can handle high pressure. Donaldson’s full product line includes high-, mid- and low-pressure filters suited to various system configurations to fit most applications. Heavy-duty, high-pressure filters sit behind pumps to protect such critical hydraulic components as cylinders, motors, and valves. Low-pressure filters are the most commonly used type in hydraulic circuits, usually as return-line filters in applications with working pressure up to 150 pounds per square inch and static pressure up to 300 pounds per square inch.
Continuous filtration of bulk fluids through dedicated off-line circuits or loops helps keep fuel, oil, and fluids clean. “As you increase cleanliness, you take out more particles,” Stein says. As cleanliness is increased, Stein suggests adding high-efficiency filtration. If capacity is added, an additional filter should be, too.
But, Baby, It’s Cold Outside!
Selecting the right filter, program, or fluid depends on the parameters of a particular application. Stein likes to start by analyzing the fluids. Test kits help determine what the contaminants are and how they got into the system. “Are they ingressed contaminants from the environment or [are they] debris the hydraulic system creates? Pump and cylinder wear creates debris and allows contaminants from the environment through the seal.” His compound solution is to add filtration capacity and put filtration in the right spot.
“We work with the customers to understand the environment and service needs to meet their goals,” Stein continues. “Everyone’s looking to extend intervals and reduce downtime.” But several issues can interfere with peak performance. Among the most demanding is temperature. “Cold issues are big, but you can experience pressure drop and still maintain the filter.”
Because of its viscosity in cold weather, however, oil can sometimes bypass the element. “With a rolloff,” Schultz notes, “you may start the truck and drive only 45 minutes in freezing weather. The pump runs 15 minutes; there’s no time for the oil to get warm, so it never gets filtered. It gets dirtier. Once it’s out of bypass, it plugs up the filter.” Schroder’s filters have a very large dirt-handling capacity that prevents bypassing during startup. “You have to size the element to last for all weather—all conditions from Phoenix summers to Michigan winters.”
You must also select the correct oil for the weather conditions because, as Schultz knows, “Most customers don’t change the oil when the temperature changes.”
If a system is faced with temperature performance problems, Betner advises consulting your lube provider for better low temperature-performing fluid. “A multigrade hydraulic fluid flows better than ISO 46-grade, 10-weight oil. You need a wider temperature range fluid that doesn’t thin out and cause leakage.” Although some people recommend a heavier grade for heat, he says, the problem can be compounded by using a heavier grade to fight leaks.
“You have to think about the operating conditions and evaluate fluid selection. In the summer, you experience power loss. In the winter, it’s sluggish and you get leakage. A good fluid acts as good as or better than 10-weight in winter, but performs like 30-weight oil in summer.”
By working with 400 contractors with heavy equipment, Citgo discovered problems with the fluids on the market.
“The idea came that hydraulic fluid usage was not up to snuff,” Betner recalls. “The selections were not right for the needs. Because they are not aware of fluid quality, customers were using industry hydraulic fluid that doesn’t meet manufacturer specs. There are properties in hydraulic fluid that are different from those of engine oil: the level of anti-wear, how it acts with water—characteristics that optimize component life perform better in the presence of contaminants.”
It sounds too simple, Betner says, but the right way is to design a “10W30” hydraulic fluid that does better.
Cold, Hard Costs
Viscosity is a huge issue, Betner says, especially in cold climates, where oxidation and sludge resulting from heat are still issues. When sludge builds up, it insulates the tank and adds to heat-related problems. Engine oil, he estimates, is changed four to six times more often than hydraulic fluid—which sometimes isn’t changed at all. “Service intervals of one year are not uncommon. Some go two to three years to save money.”
Schultz indicates that a six-month oil cleanliness level is preferred for preventative maintenance.
“The OEMs used to target a specific hour level,” he says, “but if we can keep the oil clean, we can extend the time.” A one- to two-year interval is possible, Betner believes, when operators employ a program that helps optimize cleanliness for balanced performance that meets manufacturer requirements. “If a system is well sealed, it shouldn’t get contaminated, but you must keep the engine clean.”
To achieve cleaner oil, some companies and municipalities monitor pressure restrictions in the system, Stein believes, changing the fluid when it gets to a certain level of filter load. Programs provide pressure switches, sensors, and manual indicators allowing operators to see the loading on a filter so they know when to replace it. Waste trucks will do better on a fluid-monitoring program that enables the customer to check the product periodically.
Lincoln’s new technology includes an automatic oil-fill system that keeps fluids at full level, checking the level when cool, adding oil when needed, and recording the transaction. Automatic systems and programs have a lot to offer, but they come at a price. “It’s easy talking about the benefits,” Schultz reflects, “but people aren’t easily convinced. The people who see advantages in oil cleanliness are tracking maintenance costs. It’s hard to get into municipalities, because our elements cost more. Everyone has a budget; it’s hard to justify the cost. We’re filtering things [so small] we can’t see, so there’s a reluctance to spend more money on it.”
Many municipalities have to put things out to bid, relegating products like Schroeder’s to the high end of the scale, never to be seriously considered. Nevertheless, Schultz says, “It doesn’t make sense to pay $18 for oil and stick an $8 element in.” Especially when a higher-quality element can eliminate valve problems and help systems run longer. Overall, he adds, Schroeder’s mission is to reduce costs.
“Savings are possible,” Betner promises. To save money and be less focused on areas of maintenance without increasing downtime or compromising performance, he says you must rate systems, evaluating operator performance in winter and summer and documenting component replacement and leakage histories in order to come up with a model that works for your application. That model should include a fluid that outperforms other products and practices that monitor fluid. “Hydraulics needs to be addressed—not just the engine.”