Following recommended maintenance procedures and operating practices will help you get maximum service life from the vibratory rollers in your fleet.
Whether new or used, equipment needs to be in top operating condition to be most productive. Take a ride-on vibratory compactor, for example. In order to produce a smooth mat with the desired density, all critical components need to be in good working order.
"All equipment is bright and shiny when it leaves the factory," comments Bruce Monical, Wirtgen America. "But no matter how good it is, if it's mechanical, it will eventually wear out."
The single biggest influence on how quickly that happens is maintenance. "If you follow the recommended maintenance procedures for your particular compactor, you should be able to extend the life of the machine," says Monical. "And that also influences the performance, because the better the machine is maintained, in general, the better it will perform... If the engine doesn't 'miss', if the pumps don't surge, if the drums are smooth and not pitted, if the water system is clean and provides a constant spray of water to the drum - all of that will improve the job because the performance of the machine is what it should be."
Keep it serviced
Maintenance of the engine and hydraulic system components is particularly critical. "In order for a hydraulic vibratory system to have the proper output to compact the asphalt, the engine has to run at its specified rpms," notes Dave Dennison, BOMAG. "If the engine isn't turning fast enough, the hydraulic system won't perform as designed and your vibratory performance will be diminished."
Using clean, high-quality lubricants also plays an important role in reducing wear, lowering operating temperatures and obtaining the maximum service life from components.
"Keeping the cooling system clean contributes to the lowest possible operating temperatures, which helps prolong the life of lubricants, seals and components," says Tim Sturos, product support supervisor, Caterpillar Global Paving. "Improper maintenance can lead to contaminated hydraulic oil and high operating temperatures, which cause increased wear and poor performance."
Fluid analysis will help you to more easily track lubricant condition. "Regular oil sampling helps establish the condition of the lubricants," says Sturos, "and guides equipment managers in making optimal maintenance decisions in order to avoid unscheduled downtime and excessive maintenance costs."
To ensure optimal mat quality, pay attention to the water system; in particular, make sure the scrapers on the drums are adjusted properly. "They have two functions," says Bob Marcum, Volvo Roadbuilding. "The first is to distribute water evenly across the drum. The second is to remove any material that might stick to the drum. If they're not properly adjusted, they won't do either function in an optimal manner."
Water system performance can deteriorate if you frequently use an unclean water source. "If you pull water from a ditch or lake or other unclean source, the system can be compromised as the filters will have to work that much harder to remove debris," says Dennison.
Regional differences can affect the water system, as well. If you operate in cold climates, drain the water spray system at the end of the day.
"Water in the spray system can freeze, which can damage the water pump and filter systems," says Sturos. "If the water spray system is inoperative, the compactor drums could pick up asphalt off the mat, resulting in a poor mat surface." Some manufacturers, including Caterpillar, offer an optional freeze protection system.
If you work in the South and equip your compactors with coco mats, make sure the mats are in place and contact the drum uniformly to keep it moist at all times. "When the drum is dry, hot asphalt can stick to it," says Marcum. "Each time the drum comes back around, it picks up even more. Then you have the added cost of stopping the machine, cleaning off the drum and repairing the damage to the asphalt where you picked up the material."
Operate rollers appropriately
Operating procedures greatly affect the life cycle of a compactor. "Jumping curbs, driving rather than ramping the roller off the trailer, quickly moving from forward to reverse, breaking up concrete blocks, etc., can all damage the machine," says Monical. "If you use the roller the way it's designed [to be used], on jobs it's designed to do, you will positively influence how long it lasts."
Over compaction can also have negative repercussions on roller longevity. "The energy that you create in the drum has to go somewhere," Marcum points out. "If the material won't absorb it, then it comes back into the machine. That feedback, or energy, has a high potential of damaging the isolators that allow the movement of the drum. It can also cause premature damage and wear to the bearings." To minimize and/or eliminate over compaction, establish a rolling pattern for each job and verify it through testing.
Even how you secure the roller for transport can potentially affect component life. "If you over tighten the chains, you're drawing against the drum isolators and stretching and damaging them," says Marcum. "Become familiar with the machine and know when it's secure. There is no calibration or indicator, but an inexperienced driver can become too enthusiastic and tighten the chains too much."
When maintenance isn't enough
Even with an optimal maintenance program and proper operation, you may be forced at some point to make the decision between making a major repair and replacing the unit. When an existing compactor becomes more costly to repair than to purchase, or when it experiences excessive downtime, it's likely a better option to purchase new.
"And if you ever get to the point where a machine poses a significant safety problem," says Dennison, "that's another reason to upgrade to a new unit."
When determining whether to repair or replace, take into account the costs of parts, labor and downtime required to maintain or rebuild a unit nearing the end of its service life. "Certain components may be very expensive to replace, such as heavily worn drums," says Sturos. "Consider, too, that certain replacement components may no longer be readily available or available at an economical cost."
Also ask yourself if the compactor still allows you to meet job requirements in terms of size, width, tonnage and production goals. "Essentially, ask if your current roller can keep up with the paver in production," says Marcum.
With manufacturers continuing to introduce new approaches to the compaction process, you may find that the benefits in terms of mat quality and productivity quickly offset any cost advantages of repairing an existing model.
For example, new Caterpillar vibratory rollers offer an enhanced propel control system design that produces a smoother mat by providing consistent and controlled acceleration and deceleration. "The sophisticated system can also sense when the operator requires a quick stop, providing safe stoppage when needed," says Sturos.
Hamm's oscillation technology - offered on select models - is also designed to generate a smoother surface by rocking the vibratory drum back and forth, rather than bouncing it up and down. "The drum never leaves the surface of the mat. It sends a vibratory effect, but it doesn't beat it into the material," Monical explains. "The direct affect is that you rearrange the particles and achieve the final density you need, but you don't bounce up and down. You don't ever break rock over or shatter the surface. You have an ultimately flat, smooth surface with no ridge lines or bumps."
From a productivity standpoint, after correlation on the test strip, an onboard stiffness reading enables you to evaluate the effectiveness of compaction in real time without the need to wait for additional outside tests.
BOMAG's Asphalt Manager (or "intelligent compaction") is designed to yield consistent compaction quality by taking mat readings, then automatically adjusting the drum energy into the material based on the results. "With Asphalt Manager, we're checking every square foot of the site. It's not random," says Dennison. "We also have the ability to document these results, which is becoming increasingly important for jobs that require documentation."
Some new models also include an onboard mat temperature gauge that allows the operator to monitor how quickly the asphalt is cooling. "The gauge is right on the machine, so the operator doesn't have to rely on a temperature gun or someone else to check readings," says Dennison. "We also have an impact spacing display to provide immediate feedback, so operators know if they have to adjust their travel speed."
In addition, manufacturers have focused on improving engine management with Tier III and ultimately Tier IV engines. "We can manage the engines more efficiently for better fuel consumption, while maintaining the power needed to run the hydraulic system," says Marcum.
Take the ECO-Mode introduced on BOMAG's new high-frequency roller models early last year. The engine, engine controls, hydraulic system and vibratory system all work together to provide the engine speed best suited for the job.
"Practically speaking, if a roller operator is done with a certain section and stops and comes back to neutral, they don't need to be sitting there at 2,500 or 2,600 rpm. The machine will automatically idle down to a lower level to reduce fuel consumption and noise," explains Dennison. "Our goal is to get maximum compaction efficiency while using the lowest possible amount of fuel. It also increases component life expectancy by running them at lower rpm speeds."
More comfort = more productivity
Significant advancements have been made in the operator environment, as well, with features such as swivel/sliding seats, instrument panels and joysticks that move with the operator, enhanced visibility, etc. This all adds up to a more comfortable work station where operators can be more productive for longer periods of time.
"The operator station has improved to allow better control of the machine, as well as provide a safer machine to operate," says Marcum. "Specifically, moveable seats allow the operator to position himself on the side or edge of the machine for better visibility when rolling against curbing or other obstacles. With multiple seats or rotating seats, we can put the operator on the side of the machine where he has excellent visibility to the drum edges."
Newer roller designs also feature reduced noise levels compared to previous models. "There is a lot of work put into the [engine] hood and exhaust design to keep overall noise down and away from the operator," notes Dennison.
"The operator has to be happy," he adds. "The more comfortable we can keep the operator, the more productive [he or she] will be."