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A whole new class of pneumatic-tired
rollers has evolved to deal with the pavement trends of our times.
Pneumatic-tired rollers have been a staple in compacting asphalt, chip
seals, recycled pavement and base and sub-base materials for many years, but
they have enjoyed a modest burst in popularity recently in North America
because their relatively gentle, kneading action is ideally suited to
intermediate or breakdown compaction on many modern mixes such as Superpave
and stone mastic asphalt.
As the name implies, pneumatic rollers use tires rather than steel drums
to compact material. Most have three or four tires on the front axle and
four or five on the rear; the rear tires are aligned to compact the voids
left by the front-axle tires, and to overlap the front treads to leave a
relatively even surface after each pass. By focusing compaction forces in
this manner, the pneumatic roller exerts a high percentage of the machine’s
weight per square inch of surface contact without using vibration, and it
creates a kneading action as it moves.
“Pneumatic rollers work on the principle of manipulation of the
material surface and underlying particles to squeeze out air voids and
thereby increase the surface density and bearing capacity of the material,”
explains Ingersoll-Rand’s Dale Starry. “The flexible tire surface
permits conformance of the tire to slight irregular surfaces to help
maintain uniform density and bearing capacity...[whereas] steel drum rollers
will bridge over low spots while applying excessive pressure to high spots.”
Growing usage
Of the 10 brands of pneumatic rollers, six have introduced at least one
new or re-engineered model since 2001, and four have announced new models in
the over-50,000-pound class this year. Steve Wilson, marketing services
manager for Compaction America, manufacturer of the Bomag and Hypac lines of
compaction equipment, says the increasing use of large pneumatic rollers is
directly tied to the growing use of Superpave mixes.
“With Superpave, a pneumatic can be effective working in the tender
zone of the paving temperature range where a steel wheel roller will have a
tendency to push the material,” says Wilson.
Protec America President Jim Walton agrees and points out that some
states are increasing their maximum lift-depth-to-stone-size ratio,
resulting in thicker Superpave lifts — and more tender zone problems as
compaction schemes have to account for more residual moisture in the
aggregate. “The contractor has internal stone moisture which cooks out
after breakdown rolling and manifests itself as tender,” says Walton. To
hit the high performance compaction goals laid out by states like Indiana,
which is pushing to increase from 92 to 94%, you have to roll the tender
zone with a large pneumatic roller, Walton says.
Pneumatics are also widely prescribed for the intermediate or breakdown
rolling of any mix that has large aggregate stone or angular stone that is
considered soft or fragile. Exerting high degrees of compactive force on
such mixes in a tender state with a steel wheel roller can cause the stone
to fracture, thus compromising the pavement’s structural strength. Mixes
included in this spectrum range from SMA to cold recycled pavements.
Buying issues
Competing models in the pneumatic-roller segment are differentiated in
their respective approaches to operator comfort, visibility, and controls.
An emerging area of differentiation is dealing with the tendency of
polymer-modified mixes like Superpave to stick to the pneumatic tires. The
antidote is heated tires, but getting there varies from simply operating the
machine on ever hotter pavement, which can be time consuming, to the use of
auxiliary tire heating systems. A third option, a heavy liquid sprayed on
the tires, has been introduced and has started the long process of obtaining
state DOT approvals.
New model development in recent years has also emphasized reducing the
cost of ownership by simplifying maintenance through improved component
accessibility and by reducing the frequency of required maintenance.
Long lifecycle
Compared to other types of machinery used in road construction and
repair, pneumatic-tired rollers are seldom subjected to machine-stressing
conditions and therefore tend to have long operating lives if they are
professionally maintained.
When a pneumatic roller is retired, it is usually because of an
accumulation of needed component repairs and replacements, not because of
the fatal failure of one stressed component or system.
Tires are one of the most expensive wear items on these machines.
Operators tend to expect to get around three seasons of use from their
tires, but a lot depends on tire pressure manipulations and the aggregate
content of the material a machine works in, according to Compaction America’s
Steve Wilson. “Large, sharp stone will cause shorter tire life than a
small, round stone,” he points out. “And tire inflation levels will be
job specific due to the ground contact pressures required for each
application.”
Estimates of annual usage for pneumatic rollers ranges from 500 to 750
hours for small and medium-size units to as much as 1,200 hours for large
units. Low-hour users tend to rent these machines.
Ten-year-old units are very common and marketers say there are many 15-
and 20-year-old machines still in service.
Rosco
11-wheel, 83.5-inch option for 30,500-pound machine
 New this
spring, Rosco’s
Tru-Pac 915 pneumatic roller now has an 11-wheel option, which extends
compaction coverage to 83.5 inches; the standard nine-wheel Tru-Pac 915 has
a 68-inch compaction width.
The Tru-Pac 915 has a shipping weight of 11,500 pounds and a ballasted
operating weight of up to 30,500 pounds. Ballast compartments are integrated
into the frame to enhance stability and produce a low center of gravity. The
unit features 40-degree articulation and delivers true tracking on turns.
All-wheel oscillation increases kneading action during compaction and
eliminates floating over low spots for consistent compaction.
An 85-horsepower diesel engine and hydrostatic wheel motor drive produce
speeds up to 15 miles per hour.
Click 13 on ROADFAX card
Ingram
Four redesigned pneumatics from a reborn brand
 Ingram
Rollers was resurrected by new owners at the start of 2000 and is now
marketing four pneumatic roller models and two static steel wheel rollers
from their base in Montevideo, Minnesota. The pneumatic roller lineup
includes the 30-ton RP930, the 15-ton RP915 (rigid frame) and AP915
(articulated), and the 15-ton TP1315, a towable, 13-wheel machine.
At 60,000 pounds, the RP930 is one of the largest pneumatic rollers on
the market. It has nine wheels, and a power train that includes a
152-horsepower diesel engine and a three-speed hydrostatic drive, with four
driven wheels.
All four pneumatic models were extensively redesigned and rolled out in
the spring of 2001 and feature all-wheel oscillation for complete compaction
of both level and uneven surfaces.
Click 18 on ROADFAX card
Caterpillar
Paving
New seven-wheel heavyweight can finish-roll, too
 Caterpillar
added a versatile large model to its pneumatic roller line this spring. The
seven-wheel PS-360B has a fully ballasted weight of 55,115 pounds, exerting
up to 7,874 pounds per wheel. The high-production model is recommended for
soil, asphalt, chip and seal, reclamation, and soil stabilization
applications.
Cat says the PS-360B can be ballasted with water, sand, steel, or a
combination of each, allowing it to be tailored to meet specific wheel load
specifications. The machine’s extra-wide, 14.5-inch tires produce a wide,
2.5-inch tire overlap which allows it to work on asphalt as a breakdown,
intermediate, or even a finish roller, according to the company. It has a
rolling width of 90 inches for easy coverage of a standard highway lane in
two passes.
Standard features include a fuel-saving pressure override valve in the
hydraulic drive circuit, and Cat’s High Drive system, which positions the
hydraulic pump, drive motors, brakes, and hoses in the engine compartment,
away from contamination.
Click 14 on ROADFAX card
Protec
Heated wheels for Superpave and SMA work
 Protec
introduced the Roadstar pneumatic roller earlier this year specifically
designed to compact Superpave and SMA mixes. Available as a nine- or
seven-wheel machine, Roadstar has a base weight of 25,575 pounds and can be
ballasted to 53,000 pounds.
Roadstar uses infrared heaters to maintain tire temperatures that keep
hot asphalt and polymers from sticking to the tires. Also standard is
air-on-the-go, a feature that lets the operator adjust tire pressure from
the operator station to adjust to different compaction requirements.
At 53,000 pounds, the nine-wheel Roadstar has a rolling width of 83
inches and exerts the equivalent of 640 pounds per linear inch — nearly
twice the 325-pound compaction force being required for static steel drum
rollers on some SMA mixes today, according to Protec.
Click 15 on ROADFAX card
Vibromax
Pneumatic/steel-wheel combo unit for smaller jobs
 Vibromax
says its model 255K combination roller is ideally suited for small- and
medium-sized paving jobs. The unit features a 39-inch front steel drum and
four 205/60R 15 tires with a working width of 35 inches in the rear.
Designed for maneuverability, the machine measures 94.5-inches long and has
an inside turning radius of 69 inches.
The power train includes a three-cylinder diesel engine and a two-speed
hydrostatic transmission; the company rates the machine’s gradeability to
40%. Single-lever control allows fingertip operation of forward/reverse and
vibration on/off.
Standard equipment includes pressurized intermittent sprinkler system,
and a 2-year parts and labor warranty.
Click 20 on ROADFAX card
Ingersoll-Rand
Mid-size and large models meet many needs
 Ingersoll-Rand’s
two-model line of pneumatic compactors includes the PT-125R (pictured) with
a fully ballasted operating weight of 27,870 pounds, and the PT-240R, which
goes up to 52,910 pounds. Both models have pressurized water systems with
separate spray nozzles and are designed for compacting hot-mix asphalt
and/or rolling chip/seal, soil cement, and other stabilized soils.
The 85-horsepower PT-125R has a two-speed hydrostatic transmission and a
top speed of 15.5 miles per hour; the 110-horsepower PT240R has a
three-speed transmission and a top speed of 11.8 miles per hour.
The PT-125R is available with tires of different ply ratings to match a
variety of application requirements. The PT-240R has an on-board,
operator-adjustable tire inflation system that makes it easy to adjust
ground contact area and contact pressure to meet different material
requirements.
Click 12 on ROADFAX card
Sakai
Wide line of pneumatic and combo rollers
 Sakai
now offers a full line of both pneumatic and combination pneumatic/steel
drum vibratory rollers for hot-mix asphalt finish courses and stone matrix
asphalt work.
Sakai’s TS line of pneumatic rollers feature an 81-inch rolling width
and ballasted weight up to 34,870 pounds. Both the TS200 and TS600C are
nine-wheel models and use Sakai’s own patented tire design (9:00-20-10PR)
for a wide range of asphalt, base, and sub-base compaction applications. A
2-inch hydraulically driven water pump is used to draw water from local
supplies for filling the on-board tank, for spraying water on base material,
or for transferring water to double-drum asphalt units.
For asphalt finishing, either model is available in a seven-wheel format
with a 90-inch compaction width.
Sakai
also has a four-model line of combination pneumatic/steel drum rollers with
rolling widths ranging from 47 inches for the TW350-1 to 66 inches for the
TW750.
Click 21 on ROADFAX card
Bomag
New, faster, 25-ton production roller
 Bomag
has re-engineered its 25-ton BW24R pneumatic roller for increased
productivity by increasing its travel speed and improving operator comfort
and convenience. Top-end travel speed has increased nearly two miles per
hour to 15.5 miles per hour by upgrading to a 110-horsepower Cummins diesel;
the powertrain also includes a Clark 2000 series Powershift transmission
with on the go shifting through three travel speed ranges in forward and in
reverse.
An ergonomically designed control panel highlights a reconfigured
operator’s station that reduces operator fatigue. The frame design has
been streamlined to improve sightlines to the work.
The BW24R has a fully ballasted operating weight of 52,911 pounds; each
tire’s maximum wheel load is 6,614 pounds. Its eight tires — four in
front and four in the rear — have a total coverage area of 78 inches with
a 2-inch tire-track overlap.
Click 11 on ROADFAX card
Hypac
More power and speed for big job applications
 Hypac
introduced its new C560B pneumatic roller last April. It features a
110-horsepower engine and a three-speed powershift transmission. The new
model achieves travel speeds up to 15.5 miles per hour.
Operator productivity has been improved through a redesigned workstation
and improved visibility to the front and rear. For ease of transport to and
from the job site, the machines ROPS structure is bolted to the top surface
of the roller’s frame for quick removal.
The C560B compacts a 78-inch-wide swath with four tires in front and four
in the rear. Its fully ballasted operating weight is just under 53,000
pounds. An on-board compressor, air hose, and pressure gauge make it easy to
adjust tire inflation for the best compaction on various surfaces.
Click 16 on ROADFAX card
Hamm
Four models span 10,000 to 61,700 pounds
 Hamm
markets four pneumatic roller models in North America. The nine-wheel GRW 6
has an operating weight range of 10,000 to 30,000 pounds. Its 84-horsepower
turbo diesel and hydrostatic drive train has a working speed range of 0 to
7.2 miles per hour and a top speed of 14.5 miles per hour for
transportation.
The larger GRW 10, 15, and 18 models have eight-wheel designs and a 127
horsepower turbo diesel with a three-speed powershift transmission coupled
to a spur gear box and differential set, eliminating the need for chains in
the drive system. All three have a 78-inch compaction width. The GRW 10 has
an operating weight range of 19,400 to 44,100 pounds, the GRW 15, 25,300 to
52,900 pounds, and the GRW 18, 32,000 to 61,700 pounds.
The three larger models feature dual operator stations and a dual
pivot-point steering system that maintain overlap between front and rear
tires even in a full turn
Click 19 on ROADFAX card
LeeBoy
A 63-inch, small-job specialist
 LeeBoy’s
6,388-pound model 420 pneumatic roller delivers final-pass compaction for
small projects, such as side streets, parking lots, and even driveways. Its
nine-tire format covers a 63-inch width. The combination of front-axle pivot
steer and compact design — it measures just 9-feet long and 5-feet,
3-inches wide — gives the unit excellent maneuverability.
The LeeBoy 420 is powered by a 40-horsepower diesel and a hydrostatic
transmission and operates at speeds up to 7 miles per hour. The operator’s
compartment features a bench seat and forward/reverse levers on both sides
of the driver’s console to allow the operator to focus better on the mat
during detail work.
Standard equipment includes a 93-gallon, pressurized water system that
features a hinged stainless-steel water tank to allow accessibility to the
engine compartment.
Click 17 on ROADFAX card
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