ASPHALT
PAVERS
I.
There are two basic types of asphalt pavers in the
small paver category:
A. Gravity feed or "Dump" pavers. On these
pavers the hopper lifts to allow asphalt to fall back
and in front of the screed. The gravity feed type
pavers cost less than conveyor machines. Production
is generally 25 % more with conveyor pavers than with
the gravity pavers. Job site maintenance costs are
lower with gravity fed/dump pavers because there
obviously is no conveyor system to maintain.
B. Conveyor or "Flight Chain" pavers. Conveyors
carry asphalt back to the screed. The
conveyor type pavers cost more than the gravity fed
pavers. Production is higher than with gravity pavers
and maintenance costs are usually higher.
II.
There are two distinct propulsion drive systems, wheel
or tire and track drive:
A. Wheel or Tire driven pavers. This type of drive
is more sensitive to unstable base conditions, such
as sandy or soft bases. Some geographic areas presenting
this problem are FL, Long Island, parts of MI, eastern
shore of NJ and CT, coastal areas, etc. The original
cost to purchase, as well as to operate and maintain
is less. Pneumatic tires are now foam filled (never
get a flat). Some wheel drive pavers are equipped
with hard rubber-solid tires. All wheel pavers work
equally as well as track pavers on hard base and they
work even better than track drives on over-lay work
because they run smoother, use less power to operate
and, thus, can pave faster.
B. Track drive pavers. This type of drive presents
a larger "foot-print" to distribute the
weight so the operation is much less effected by sandy
or soft bases. Track drive pavers cost more to purchase,
operate and maintain. There are two type of track
drives:
1. Friction Drive - utilizes a solid forklift type
tire running inside a steel track. This type
runs smoother, faster and costs less to manufacture,
but can slip if the tracks are loose, the wheel diameter
wears down, and/or water/diesel fuel /oil, etc. gets
on the inside of the track.
2. Sprocket Drive - utilizes a steel sprocket that
pulls against a chain to which track
shoes are welded. This system, while costing more
to manufacture, usually runs with more “bounce” and
costs more to maintain. It provides a non-slip drive.
III.
Screed. This portion of the asphalt paver levels,
spreads and pre-compacts the asphalt. Screeds on all
small, self-propelled pavers are full floating screeds
and have a crown adjustment at the center of the screed.
Screed may be vibratory (this satisfies DOT and other
specification writers) and does help, somewhat, to
slick off the surface of the asphalt as it is being
laid. Most pavers are available with screed heating
systems. There are three basic ways to heat a screed:
A. Propane system.
B. Diesel system.
C. Exhaust heated system. A flex-pipe running from
the engine exhaust to the screed.
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