Much of the undercarriage-related owning and operating costs for pavers and milling machines are driven by your maintenance practices. As with most tracked equipment, a little attention goes a long way.
Track tension is perhaps the largest cost driver. Adjustment naturally gets looser with wear. "Most of your wear comes from internal pin and bushing wear, which you really can't see," says Rob Hannan, segment manager for milling products at Volvo. "That makes the track chain a little bit longer, so you have to take up the slack. If there are 30 pins and bushings and you take .5mm wear on each pin, it would be 15mm, which is over half an inch."
While periodic adjustment of track tension is needed, improper adjustment can do more harm than good. "Excessive track tension can cause excessive wear not only on the track components, but also on the drive system as the track will be more difficult to operate," says Dennis Clausen, director of training, GOMACO Corp.
"Over-tightening is always wrong," agrees Guido Bottin, vice president of operations, Berco. "It leads to accelerated wear of the components (pins, bushings and sprockets) and can cause breakages, especially in the steel chains. On the other side, running with a loose undercarriage may lead to detracking of the chains with possible damage to the system."
Advice for managing tension
Every manufacturer recommends checking track tension more or less frequently according to the load conditions, Bottin notes. For new machines with bolt-on shoes (steel only or rubberized), Berco recommends checking both tension and tightness of the bolt after the first 50 hours for heavy-duty use, or after the first 100 hours for moderate to light-duty use. "Additional checks should occur every other 200 to 250 additional hours of usage," he adds.
More frequent track tension checks may be required for pavers due to the heavy loads they can carry. "The operating weight on pavers changes dramatically when the machine is loaded - up to double compared to the unloaded condition," says Bottin. "If not properly tensioned, slippages of the undercarriage are possible and have to be avoided."
GOMACO Corp. recommends checking tension weekly on its larger pavers. (Smaller models have automatic tensioning.) "If the track is too tight, excessive wear will occur on the components. If the track is too loose, it is possible to 'walk' out of the track in a turn," Clausen explains. "Items that will affect tension are the type of material the track is running on (e.g., loose sand vs. a hard surface) and if concrete is allowed to get into the track."
For its milling machines, Volvo advises checking track tension every 50 hours to minimize potential problems. "With the style of sprocket most milling machines run, if you run it too loose, the sprocket tries to climb on top of the bushing, then it fires off the sprocket," says Hannan. "When it comes off, it sounds like a shotgun going off. It throws a real strain on your planetary and other track components.
"If you run the tension way too tight," he continues, "then it takes a lot more hydraulic pressure to turn the track. You can get them tight enough that the machine will not move. We have seen where they were running extremely high hydraulic pressures. We backed the track tension off and everything calmed down."
Also inspect other wear items on a regular basis. "The idler and sprockets do need to be inspected periodically," says Clausen. "Check with the component manufacturer for acceptable wear amounts. The hardware attaching the drive sprocket to the drive needs to be checked for proper torque at proper intervals." Refer to the machine service manual for specific recommendations.
Cleanliness is key
Cleaning tops the list when it comes to paver maintenance. "A buildup of hardened concrete can cause excessive wear on components and make servicing difficult. This includes the tracks," says Clausen. "On concrete paving equipment, the tracks should be cleaned as soon as possible."