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If gauging immediate productivity is your goal, zero in on the screed area.
 This view, looking down into the hydraulic compartment, shows the general-function pumps to the left, and the auger and conveyor pumps to the right. All are in good condition and no major leaks are evident. |
If
you’re in the market for a used paver, it’s always a good idea to bring along
your paving foreman or someone else in your organization who’s around pavers every
day, says Paul White, service manager for Colwell Equipment, Canton, Michigan. "A lot
of the time, the guy who signs the checks doesn’t get out on jobsites the way he used
to," he notes. "If you want to get a good, productive machine, go over it with
the guy who runs it and the guy who’s going to fix it."
Our inspection paver was a 1997 Blaw-Knox 5510 rubber-track model with 3,837 hours on the
meter. "Most of the pavers in the Detroit area average around 1,500 hours a
year," says Bill Blair, Colwell sales manager.
You’d think the harsh Michigan winters would limit a paver’s yearly usage
somewhat, but Blair says contractors tend to push the machines hard when the weather is
good. "We take trade-ins on about 60 percent of our new paver deals," he says.
"Many of these machines are only three or four years old. That’s not bad
considering that pavers are so rebuildable; they can last forever if they’re taken
care of."
White says there is almost
 The screed plateÕs thickness must be measured to ensure youÕre buying a productive paver. Measure both the front and rear of the plate on both sides of the machine. Ideally, you want a consistent thickness of around 1/4-inch. |
never a
damaged paver section that can make the machine a bad purchase. "It all boils down to
how much time and money you want to spend on a machine," he says. "Even
worst-case scenarios like a blown engine or a twisted hopper can be repaired to give you a
productive machine."
When appraising a used paver, White and Blair first walk around the unit and look for any
severe damage or obvious signs of neglect. "The most common damaged area is around
the front of the hopper, where trucks often run into the paver," White says.
With that in mind, your first move should be to check the hopper’s leading edges for
impact damage and inspect any weld lines at the front of the machine for stress cracks
— all sure clues that the paver was run into by a dump truck.
But bear in mind that stress cracks and dents are relatively minor compared to a
collision-damaged hopper that has been twisted out of alignment with the rest of the
machine. Both White and Blair stress that you examine the hopper from a short distance
away and make sure that it is properly aligned with the rest of the
 Track inspection is straightforward: Watch for hydraulic leaks around the drive motors, and inspect the tracks and bogies for damage. |
machine.
Continue your walkaround by giving the unit’s drive system a brief inspection. On
track pavers, you’re essentially gauging the general condition of the tracks and
looking for hydraulic leaks from the drive motors. On wheeled units, look over the tires
for excessive wear or abuse, then bend down and inspect the drive system for any signs of
hydraulic leaks.
At the rear of the paver, look over the screed for impact damage, then climb up to the
operator’s station and check out its condition. Expect some weathering, but mainly
look for signs of abuse such as torn seats or broken instrument glass.
Topside checks
One good thing about appraising asphalt pavers is that in spite of their complexity, and
the multiple functions they’re required to carry out simultaneously, there are few
hidden or hard-to-reach components. Almost all important machine components are outside,
where they can be inspected easily.
This is the case on the Blaw-Knox 5510. Here, atop the paver and just in front of the
operator’s stations, are service panels which give excellent access to the entire
engine, radiator and hydraulic pumps.
Start with the engine compartment. On the 5510, access panels are directly in front of the
right-side operator’s station. You should
 Make sure the hopper deck and conveyor system flight chain are in good condition. The chain should be free of bent or twisted sections. Test the thickness of the deck as well. |
check the
oil, noting its general condition. Be watchful for any trace of coolant on the dipstick.
Coolant usually shows up as a milky-looking substance clinging to the stick, and is a sure
sign of a blown head gasket. You should also look carefully for any oil or exhaust leaks
and signs of engine blowback. Also examine the drive belts.
Next have your helper move to the right side of the paver and open the radiator service
panel. There will also be a top access panel that you should open. Making sure the system
is cool, carefully open the radiator cap and verify that there is plenty of coolant. It
should also be in good condition, with no oil or rust present. Replace the cap, and
inspect the top portion of the radiator for leaks. Also examine all radiator hoses. Be
alert for dried out or ballooned hose sections. These are signs that the hose will burst
soon.
While you’re inspecting the top part of the cooling system, your helper should be
going over the main body of the radiator. He should primarily look for signs of leaks
(which usually show up as white streaks on the metal), and make sure the
 guest inspectors Bill Blair (left) and Paul White. |
cooling
fins are not bent or damaged in any way.
Close the radiator panels and move to the paver’s left side. Again there are access
panels on both the top and side of the machine. The unit’s hydraulic pumps are
clustered together in this area.
Looking down from the top into the 5510’s hydraulic pump compartment, you will see
four different pumps and their assorted hose assemblies. To one side are the propel pumps,
which handle the paver’s general hydraulic functions. To the other side are pumps for
the auger and conveying systems.
Between you up top and your helper on the ground, you should be able to see almost every
angle of each pump. Look carefully for any signs of hydraulic leaks. Shine a flashlight on
the pumps themselves, as well as on the floor of the compartment where leaked fluid can
accumulate. Also check all the hose assemblies for leaks, and note their general
condition.
Leave the access panels open once you’re through inspecting the hydraulic
compartment. When you start the paver in a few minutes, you’re going to return to the
hydraulic compartment to verify that there are no leaks and listen to the pumps as they
work.
Screed and auger inspection
Move down to the rear of the machine and examine the screed. Blair says he tends to pay
more attention to the screed than any other part of a used paver. This, he says, is
because the screed — more than any other component — determines how productive a
used machine will be.
The most crucial measurement, Blair says, is the thickness of the screed plate itself.
Bend down and measure the thickness of the plate at its front and rear sections, on both
sides of the paver. A new screed is 1/2-inch thick. Odds are, the screed you’re
looking at won’t have that much thickness left. A good measurement for a screed plate
on a used paver is 1/4- to 3/16-inch.
Bear in mind that screed measurements can tell you a lot more than just how much plate
life is left. Your thickness measurements should be the same on each side of the paver. If
one side of the screed has worn more than the other, it’s a sure bet that the paver
is running crooked, or that it has joints out of alignment on one side.
The back edge of the screed will always be a bit thinner than the front edge. But if the
front edge of the screed is much thinner than the rear, it’s a good sign that the
operator ran the paver on its nose too often, which means the screed will have to be
replaced before you’ll be able to lay a decent mat with that machine.
Once you’ve checked the screed, look over any hydraulic or drive components mounted
at the rear of paver. You’re looking for leaks, but any hydraulic cylinders there
should also be inspected for damage. Pay close attention to the cylinders’ rod
sections and make sure they are not pitted or scarred.
The auger is mounted below and in front of the screed. The main concern here is auger
bearing wear. The best way to check this is to simply grab hold of the auger, give it a
good tug, and see if it has any play. An auger in good shape will move either very little
or not at all. But if its bearings are shot, a lot of play will be evident, and
they’ll soon need replacement.
Before you move your inspection to the front of the paver, look over the burner controls,
which are usually located atop the screed. You’ll want to test the burners thoroughly
once you’ve started the paver. But for now, just make sure they’re in good
shape.
Front end checks
If the hopper is not twisted out of alignment with the main body of the paver, then the
front end paver inspection is pretty straightforward. The most important component to
check is the flight chain in the hopper’s floor. Make sure its links are in good
condition and haven’t been damaged in any way. Bent or twisted sections are a common
problem, according to White, so make sure all of the chain is in good shape.
A final — but tough — check is to accurately determine the condition and
thickness of the hopper deck. A trick Blair and White use is to take a metal bar about 3
feet long and thump the deck in several places inside the hopper. If the deck is in good
shape, you’ll hear a good, solid bang when the bar hits metal. Listen for any brittle
or weak-sounding impacts. Blair says while performing this check he’s actually put
the bar all the way through the beds of some badly corroded hoppers.
Running the machine
Now it’s time for the acid test: starting and running the paver. Both White and Blair
stress that this is essential for gaining a clear picture of a machine’s condition.
And, although you’ve thoroughly examined the machine by this point, they say
it’s a good idea to repeat most checks while the engine is running.
Once you’ve started the machine and allowed it to warm up, put it through all of its
functions. As you do so, Blair says your main concern is to be alert for any unusual
noises. In addition, you want the paver to run smoothly. Any hesitation or jerking
movements are a sign of potential trouble, whether it’s the auger you’re running
or the flight chains.
And remember that oil leaks can be easily washed away and won’t show themselves again
until the machine has been run for a little while. So it’s always a good idea to
re-inspect the drive motors as well as the engine and hydraulic compartments once
you’ve finished test-driving the paver.
Our guest inspectors
Colwell Equipment, Canton, Michigan, was founded in 1969 when Bud Colwell bought out the
dealership he was working for and went into business for himself. Bud
"semi-retired" four years ago, and today his son Chris handles the day-to-day
responsibilities of running the company, which serves Detroit and the entire lower
peninsula of Michigan.
Colwell specializes in roadbuilding equipment, including the Blaw-Knox and Ingersoll-Rand
paver lines, as well as Thomas and Wacker equipment.
To help us assess a used asphalt paver, Colwell lent us the services of Bill Blair, sales
manager, and Paul White, who serves as service manager for the company. They have a
combined total of more than 60 years of experience in dealing with new and used asphalt
pavers.
-- Jack Roberts