When a concrete paver fails in the middle of a pour, the costs mount with every minute of downtime. “You’re dealing with a product that is non-salvageable,” says Dennis Clausen, director of training at Gomaco. “The time you have to work with it is very limited. If you have a major failure and you have to shut down, you’re going to lose whatever concrete you haven’t gotten under the machine.”
In highway paving, it’s not unusual to have 20, 30 or even 50 yds. of concrete on trucks or laid out in front of the paver. “If the paver breaks down, it’s a major problem,” says Clausen. “That’s all throwaway material unless you have someplace to take it and utilize it. But usually if it’s on the ground already, there’s not much you can do with it.”
Even on smaller jobs, the costs can be substantial. “If the machine breaks down with a lot of concrete in it, the cleanup is very difficult because you don’t have an onboard cleaning system,” says Craig Neuhardt, vice president, Power Curbers Inc. “You also have all of the associated downtime. You have a five- or six-person crew that suddenly has nothing to do. You might have two or three ready-mix trucks there, each with 8 or 10 yds. of concrete — that’s roughly $800 a piece of concrete you can’t use. And you have a customer that you’re pouring curb for that’s screaming at you. The end result gets very, very expensive.”
Avoiding failures in the middle of a pour almost always comes down to properly maintaining the machine. “The cost of the parts, the cost of the oil, the cost of the time to wash the machine up are very minimal compared to what happens if it breaks down while the machine is operating,” says Neuhardt.
Cleaning reduces wear
For concrete equipment, probably the biggest contributor to unscheduled downtime is lack of cleanliness. “Because concrete is such an abrasive material, when you don’t clean it very well, it can have a dramatic effect on anything that moves,” says Neuhardt.
Especially susceptible to wear are belt or auger conveyor systems. “If something is conveying concrete, it’s wearing and it’s going to break sooner or later,” says Neuhardt. “The mechanical devices — chains, belts, auger flightings, bearings, etc. — are just exposed to so much concrete that they are a very routine maintenance item.”
Poor cleaning practices can also effect paver operating performance. “If the paver has concrete built up all over, it’s going to be harder to make adjustments,” says Clausen. “It’s going to be harder to get a good finish coming out of the product. And each day you neglect to clean it, it’s going to be harder when you do decide to do it.”
Manufacturers recommend cleaning the machine on a daily basis. To make this task easier, some contractors will use special coatings on areas that come into contact with the concrete. “They basically coat the machine to provide almost a ‘wax’ that helps keep a lot of the concrete from sticking; or what does stick washes off easier,” says Neuhardt.
After washing, it’s a good practice to lubricate the machine per manufacturer recommendations.
“Since you have to use fairly high-pressure water to wash the machine down, [some contractors] will go ahead and grease all the bearings and check other areas after the machine is cleaned,” says Neuhardt. “It forces the water out of the bearings and makes sure everything is lubricated. Then when they start the day, they don’t have to worry about doing it.
It ties all of that service into a one-shot deal.”
Inspect before and after use
As with all equipment, it’s important to perform a walkaround inspection of the paver prior to use. This includes performing any necessary lubrication and checking levels of critical fluids. “If everybody just checked the fluids on a daily basis, life would be a whole lot better,” notes Neuhardt.
Prior to startup, operators should:
Any repair or replacement of parts should be completed prior to operation. “That way, you can do it on your schedule rather than having that emergency downtime when you have concrete in the machine,” says Neuhardt.
Because pavers are often left on site, fuel is typically brought to the machines each day. This can potentially lead to contamination of the fuel system. “Whether it’s in the storage or transfer system or in the machine itself, it’s fairly easy to get water buildup in the fuel system,” Neuhardt points out. “It’s also easy to get dirt in the system by carrying fuel to it at 5 or 10 gal. at a time.”
Prior to fueling, Neuhardt recommends, “Make sure that the fuel supply is very clean and doesn’t have water when it gets to the machine. Also make sure you maintain the fuel filters and drain the water out of the system.”
The end of the work day is a good time to check filter pressure. “Make sure you’re not running a high filter pressure and need to replace filters,” Clausen advises.
It’s also a good time to perform a secondary inspection of the machine. “At that point, you’re going over the machine fairly closely to make sure it’s clean, and you’re touching a lot of places because you’re doing the lubrication,” says Neuhardt. “It’s a great point to look to see if something came loose, if there is a weld crack, if a hydraulic hose has started leaking or anything like that.”
Monitor wear prone areas
Of course, there are other areas of the paver that should be monitored on a regular basis.
To ensure proper operation, follow manufacturer recommendations for servicing conveyor drive mechanisms. Also monitor the conveyor belt wiper for wear. “Sooner or later, it gets worn to the point where it doesn’t clean the belt off and you end up getting concrete splatter all over the place,” says Clausen. Replace the wiper as needed.
Check cover plates around the paver to determine if concrete is getting into areas it shouldn’t. “If concrete can get up and around the cover plates, we normally recommend sealing them by putting silicone sealer around them,” says Clausen.
On curb and gutter machines, check the trimmer regularly for signs of wear or damage. “The trimmer is always exposed to the dirt. On our machines, nearly half of the engine horsepower can go through the trimmer at some point. It’s working very hard and it’s in a very harsh environment,” says Neuhardt. “You have cutting teeth, bearings, a drive mechanism — all those pieces have continual wear on them.”
To ensure optimum trimmer performance, service the trimmer as specified in the equipment service manual. Repair or replace any worn or damaged components as needed.
The high cost of failure
Paver manufacturers can’t emphasize enough the importance of following recommended service intervals for critical machine components. Failure to do so can be very costly.
For example, both trimmer and crawler drives typically use a planetary gearbox, or torque hub, as the main drive unit. “Generally, with good maintenance, a crawler drive torque hub should last the life of the machine, say 5,000 to 7,000 hours,” says Neuhardt. “However, if someone allows it to leak or doesn’t keep the oil refreshed in it, it might not last 500 hours. A replacement gearbox can be $1,800 to $2,500, or up to $5,000 on bigger equipment.”
A replacement engine may cost around $10,000, depending on the size of the machine. “Lack of regular maintenance on the engine, or allowing it to overheat because you let concrete build up on the radiator, could shorten engine life from 6,000 to 7,000 hours down to 2,000 to 3,000 hours,” Neuhardt points out.
Even belt conveyors can drive up operating costs if not properly maintained. “On a belt conveyor, a complete rebuild for the belts, rollers, chain drive, etc., might be somewhere in the $2,000 range,” says Neuhardt. “The guy that keeps it clean and washed up might do [a rebuild] every two or three years. A guy that doesn’t keep it clean might do that as much as twice a year.”
Neuhardt believes keeping pavers operating — and maintenance costs under control — ultimately comes down to two key points. “Plenty of oil and grease and a lot of clean water,” he says, “and you can save yourself literally thousands and thousands of dollars spent on metal parts.”
Maintain Good Vibrations
Vibrators are a crucial component of concrete pavers. If a vibrator is not performing up to specifications, the result can be poor consolidation and compaction of the mix.
Randy Starr, vice president - sales and marketing at Minnich Mfg., recommends disassembling vibrators for preventive maintenance at the end of every season or on an annual basis. This includes taking the eccentric assembly off the vibrator to check for bearing wear. “At the same time, you can check to make sure the motor does not have a seal leak,” he says. “If the motor does not have a leak, you can either reassemble the vibrator or service and replace the bearings as a precautionary measure, and be ready to go next season.”
While vibrators don’t require daily maintenance, they should be checked prior to paver operation to ensure they are all operating properly. “They can also be checked at the end of the day, when the oil is hot and warmed up to operating temperature, to see that they are still functioning and/or running up to speed,” says Starr. A hand tachometer can be used to make sure the vibrations per minute are set according to project specs.
An alternative to this manual method is an automatic vibrator monitoring system. According to Starr, a 24-vibrator Minnich AutoVibe II system can cost around $25,000, depending on features. He notes that the benefits can make this investment worthwhile even on projects where they aren’t required.
“The benefit of the monitoring system is that the operator knows at all times what the vibrators are doing,” notes Starr. “There are alarm parameters that can be entered into the system so that he can be alerted to any vibrator that falls outside of those parameters.”
Parameters can be set for both minimum and maximum operating speeds. It is also easy to fine-tune vibrators to ensure they are all working at the same speed setting.
Some systems, such as the AutoVibe II or III versions, also have the ability to log and store data. “Down the road, if there is a problem with the slab, you can go back to your logged data and verify that at this point in the slab, the vibrators were all running to specifications,” Starr points out.
Monitoring systems also offer the potential to help extend vibrator life. “A contractor may find he is running his vibrators faster than he needs to. He can slow them down to a point where he is still getting the required consolidation and compaction of the concrete,” Starr explains. “The slower you can run the vibrators and achieve the consolidation needed, the longer you can prolong the life of the vibrator.”