Meet the Mallard self propelled articulated Duo-Pactor the only single machine equipped for complete compaction from fil to finish. The reason: the Duo-Pactor provides both high pressure pneumatic rolling for deep compaction and controllable steel-roll pressure for surface compaction. The result: this one machine can handle all the jobs normally requiring several single-purpose compactors - at a tremendous saving in time, operating expense and equipment investment.The Duo-Pactor combination rolling produces higher, more uniform densities than are obtainable with conventional pneamatic tyres form deeply compacted tracks of high density, leaving spaced ridges for rolling to added density. Heavy steel-roll exerts enormous contact pressure to force the ridges down between the side walls of the compacted tracks, unifying densities across the entire rolling width.By hydraulic control the operator has complete selection of the method of rolling - from full steel to full rubber, and the unlimited positions in between - allowing variations of contact pressure to meet the requirements of each stage of compaction.

Duo-Pactor rolling speeds are fast enough to keep pace with scrapers, allowing thin lift compaction. Unique wheel suspension allows all types to conform to irregular surfaces and spreads the pressure equally on each compaction tyre. The positioning of the steel-roll ahead of the wheels permits its use as a "clodbuster" and to press other hard materials into the grade, eliminating possible damage to the tyres. Being highway legal and having a road speed of 32kmh, the Duo-Pactor again spells PROFIT in reducing the cost of a truck-trailer for short job-to-job moves.Only the Duo-Pactor combines both steel and pneumatic rolling in one low cost, self propelled compactor. The advantages of using one machine...one operator for all compaction jobs are evident. But there are other advantages that are even more important.

Compaction Quality is Improved Used as a pneumatic or steel roller, or both, the Duo-Pactor delivers superior material density and stability. Higher compaction pressures are achieved by smaller diameter tyres having minimum surface area for maximum surface pressure. material is compacted deeper requiring lower gross load. This important Duo-Pactor feature gets greater densities in low bearing value materials where subgrades flex under heavier compactors. Note how closely spaced, small diameter rolling tyres  form alternate compacted tracks of high density, while leaving ridges of less dense material. Further rolling with rubber will not smooth out these ridges. The closely spaced tyre form densely compacted tracks with minimum material displacement. Lowering the steel-roll chokes ridged material down between the tyre tracks, unifying density. However, application of the steel-roll  presses ridges downward to the level of the areas already compacted, witout material displacement. The result is a smooth, level finish of uniform density. Minimum Material Displacement With either deep or thin lifts, material displacement is the arch enemy of uniform, low-cost compaction. Displacement takes place when wheel loadings exceed the bearing value of the material being compacted. The wider the tyre spacing, the greater the displacement. The Duo-Pactor's pneumatic roll consists of eight small diameter tyres (7.50 X 16) mounted in closely spaced pairs. To confine surface pressure, the gap between each pair of wheels under load is only 50mm. For this reason, lateral material displacement is held to a minimum.

Uniform Contact Pressure At All Times
The Duo-Pactor pneumatic roll has an exclusive torsion spring suspension system that assures uniform contact pressure. More uniform pressure is maintained across the rolling width on crowned surfaces. Also, when the torsionally sprung wheel pair of the Duo-Pactor is tilted due to surface irregularities, the spring "winds up", holding the load on each tire uniform, but when a freely pivoted wheel pair of a conventional compactor  is tilted, most of the load is shifted to the low tyre, causing non-uniform compaction.

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