Hoping the slowdown ends in one pass

Dec. 28, 2000
Wider, but with a little less Span from Washington

Wider, but with a little less Span from Washington. Drum sizes and the economy are the talk of the compaction equipment market these days.

Wider, but with a little less Span from Washington

Wider, but with a little less Span from Washington. Drum sizes and the economy are the talk of the compaction equipment market these days.

The industry as a whole is drifting towards a soft bottom, which is in part due to negative current coming from stock market instigator Alan Greenspan.

"If you listen to some of the financial reports . . . (Alan) Greenspan now admits to saying, ‘well, maybe I reacted a little too quickly, too hard, and in turn maybe I sent these interest rates in a tailspin the wrong way too fast," Steve Wilson, manager of marketing services for Compaction America, told ROADS & BRIDGES. "He’s hoping to back off to where we have a soft landing. Hopefully this is a short-lived bump in the economy."

Then there’s the pump in the economy. The stance state’s take on fuel taxes are effecting everybody in construction. If a state removes the tax, federal funding under the Transportation Equity Act of the 21st Century will take a cut.

"It’s matched dollars, so if states aren’t getting any money from the gas tax then they won’t get the federal money," said Wilson. "We’re a little concerned how that might impact things, but it’s still early in the game."

The high price for fuel also is leaving contractors strapped for cash. Higher operating expenses means less capital to buy equipment, and the move now is toward the rental side of the business.

"A lot of the major contractors have been going to rental instead of purchase," said Wilson.

Whatever lot compaction equipment sits on, expect the drum sizes to expand. Much of the work today involves the reconstruction or repair of major roads, which requires mainline paving in a high-productive type of environment.

"The machines have wider, larger drums to keep up with that high productivity," said Wilson. "There’s also a movement towards higher frequencies."

As far as the future of the market is concerned, where there’s a soft bottom, there’s a soft landing.

"We go through these peaks and valleys. Sometimes the valley will be more severe, but normally it will be short lived and we’re back crawling to the top again," added Wilson.

Everybody is placed on a level-playing field when it comes to ROADS & BRIDGES’ equipment profile. The following is a brief description of some of the major players involved in compaction and compaction testing.

Fills the bill

Sakai America Inc., New Castle, Del., believes it has the asphalt roller line-up to "meet every contractor’s size and budget."

The new team includes the SW850, SW800, SW650, SW500-1, SW350-1 TW500 and the TW650.

The SW850 offers 33,290 lb per drum centrifugal force over 79-in. drums, while the SW800 offers 27,120 lb of centrifugal force with its 67-in. drums.

Both machines feature 4000 vpm vibration frequency, dual amplitudes, three switchable frequencies and high force outputs designed to reach density fast.

A multi-position operator station provides visibility of drum-edge, curb, drainage inlets and other obstructions.

Mid-size models SW650 (58-in.-wide drums and 15,430 lb of force), SW500-1 (51-in.-wide drums and 6,610 lb of force) and SW350-1 (47-in.-wide drums and 4,630 lb of force) handle compaction of smaller roads, road shoulders and other mid-capacity jobs.

The machines feature high forces and impact frequencies to speed compaction of various mix designs, according to the manufacturer.

Two-speed hydrostatic systems provide quality traction while overcoming bow wave build-up.

Making utility room

A compaction operator can have some quiet following recent additions made by Caterpillar, Peoria, Ill.

The company claims to have reduced the operating noise on the new CB-214D, CB-224D and CB-225D utility asphalt compactors.

The CB-214D is a double drum with a 39-in. compaction width. It has an operating weight of 5,355 lb and a tight turning radius.

A 47-in. compaction width is achieved by the CB-224D, which also is a double drum and carries an operating width of 5,750 lb.

The CB-225D is more versatile because of its combi configuration, according to Cat. The machine has a 47-in.-wide drum at the front, and the rear end is equipped with four smooth tires. It has an operating weight of 5,265 lb. The combi roller can take the place of two machines by providing the features of both a vibratory and a pneumatic.

All three models are powered by a 3-cylinder Caterpillar 3013 diesel engine and have a high-frequency vibratory system that generates 3600 vpm. The CB-214D and CB-224D provide two vibratory modes, front drum only or both drums.

A hydrostatic propel system provides smooth starts and stops and service braking. A brake interlock prevents the machines from being propelled while the brakes are applied.

The rollers also have a pressurized water spray system that allows water to be sprayed over the drums. Spray modes are constant, off or intermittent.

They can squeeze in

Ammann America Inc., Jacksonville, Fla., has invested dollars so that its AV/H rollers can maneuver out of tight quarters.

A tight turning radius, minimum dimensions and high curb clearance give the tandem vibrating machines the ability to work out of small areas.

The series is symmetrical. The weight relationship to front/rear, left/right are in equilibrium, which offers equal compaction of all surface courses.

Split drums drive independently to ensure better compaction and a clearer finish.

Other features are two large corrosion-free water tanks (900 l) and a pressurized sprinkler system with adjustable intervals.

Ammann offers three versions of the AV/H series—E, N and T.

Here it is, years later

Dynapac, Schertz, Texas, took the time to build the CC522, which is the culmination of years of research.

The 14-ton double drum asphalt compactor delivers the right specifications for Superpave mixes, according to the company.

It covers a standard 12-ft-wide asphalt mat with just two laps with a 10-in. overlap. Large diameter drums allow for less rolling resistance, which in turn means less mat markings and less fuel consumption.

The CC522 allows the operator to roll at up to 3.5 mph, while maintaining proper drum impact spacing and density. This is due to its large drum diameters (55 in.) and high frequency (3000 vpm). A speed limiter on the forward-reverse lever allows the operator to set the rolling speed in forward and reverse one time.

Two standard features on the roller eliminate the guesswork from the operator. The automatic vibration and automatic water controls are automatically turned on-off as the roller goes below .5 mph. This feature assures that the roller will not vibrate in place (stopping or reversing) and the water will not be wasted. The water spray system is comprised of a water pump at each drum with an emergency back up, where one pump can wet both drums.

Time to PAC

It’s not a new set of luggage, but a new series of vibratory asphalt compactors from Ingersoll-Rand Co., Bethlehem, Pa., called DURA-PAC. Models included in the line are the DD-12, DD-14, DD-16, DD-24 and DD-30.

DURA-PAC series compactors feature centrifugal forces ranging from 3,300 to 7,500 lb and provide the compaction necessary to achieve maximum density and smoothness in fewer passes, according to the manufacturer. The force is designed proportionally to match drum width with overall output, and operators can choose front drum vibration only, double drum vibration or static mode. Each machine offers a 4000 vpm frequency.

A large capacity 79-gal, rationally molded, polyethylene water tank is available on the DD-24 and DD-30 models, while all other compactors are equipped with a 52-gal water tank. Variable water flow control and spring loaded, self-adjusting rubber wipers distribute water evenly across each drum.

A necessary adjustment

The BOMAG BW151AD-2 tandem vibratory roller, a product of Compaction America, Kewanee, Ill., takes directions from a compaction control system that automatically adjusts the roller’s amplitude to suit the current stiffness of the material being compacted.

The Variomatic system eliminates the problem of overcompaction and guesswork on the part of the operator, according to the manufacturer, and is ideal when dealing with Superpave mixes, which have a higher percentage of coarse aggregate.

The BW151AD-2 features a 66.1-in. drum width with vibration frequencies of 3300 vpm in the front drum and 2400 vpm in the rear drum. Independent vibration control of either drum is standard for increased versatility.

Water spray delivery on the BOMAG BW120AD-3 tandem vibratory roller now stops automatically when the travel lever is placed in neutral, thus extending operation between water tank refills.

The machine’s 47.2-in.-wide drums exert up to 9,225 lb of centrifugal force, and vibration frequencies are 3300 and 3960 vpm.

An oscillating, articulating center joint with +/-12 degrees of oscillation permits full drum contact on irregular terrain.

Powered by a 33-hp, air-cooled Deutz diesel engine, the BW120AD-3 features a top travel speed of 6.5 mph and maximum gradeability of 40% without vibration.

Sensing it

Instead of beating the heat, American Compaction’s HYPAC wants to work with it. The C778B and C766C double-drum vibratory compactors now come with an asphalt mat temperature sensing system (AMTSS).

The AMTSS measures the surface temperature of the asphalt as the compactor rolls across the mat. A platform-mounted display allows the operator to monitor mat temperature without stopping or getting off the machine.

A Multi-System Performance Indicator (MSPI) is another perk for the operator. The MSPI allows the operator to input maximum working speed and automatic vibration start/stop as well as front and rear drum vibration frequency and amplitude.

Hydrostatic drive delivers speed and directional changes, with speeds infinitely variable from 0 to 5 mph in low range and 0 to 10 mph in high.

HYPAC has added a high output (HO) option to the C766C. The HO option boosts vibratory frequency and centrifugal force, permitting faster rolling speeds while "maintaining compaction quality."

In low amplitude, the C766C with HO option produces 3800 vpm and up to 22,425 lb of centrifugal force. In high amplitude, the unit produces up to 29,775 lb of centrifugal force and 3400 vpm.

Tru’s story

The Tru-Pac 915 pneumatic-tired roller from Rosco Manufacturing Co., Madison, S.D., offers an articulated design that provides true-tracking and full-width compaction, especially in tight areas. Frame articulation is rated at +/-40 degrees, while the hitch oscillates 10û to either side of center.

Ballastable up to 30,500 lb, each of the nine wheels delivers approximately 3,500 lb of compactive force to the work surface. Integrated directly into the frame, ballast compartments enhance the compactor’s stability with a low center of gravity.

Cocoa mats evenly distribute water over each tire.

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