We’ll wrap up our look at how various types of compaction equipment have evolved with a hybrid machine, the combination roller.
We’ve seen how different types of rollers achieve different results on asphalt pavement, especially pneumatic rollers kneading and sealing the material, tandem rollers providing a full-width finished surface, and vibratory compactors having the ability to produce a variety of results based on the material being compacted and the amplitude and frequency of the drum’s vibration.
But in some cases, it proves advantageous to combine two types of rollers into one machine, whether static and vibratory or smooth drum and pneumatic tires. The logic behind the design is simple: by combining two machines into one, ownership and operating costs are reduced while producing the results of both.
For example, with a combination pneumatic and vibratory drum roller, the pneumatic tires provide the initial compaction, and the drum finishes the surface. The drum can follow the tires in line, or be offset from them by crab steering.
One manufacturer, Bomag, markets these machines for compaction of joints, residential streets and recycled asphalt. Bomag put special emphasis on its suitability for relatively unstable mixes and on tight curves; in both situations, the tires worked to reduce side displacement during compaction.
The Historical Construction Equipment Association (HCEA) is a 501(c)3 non-profit organization dedicated to preserving the history of the construction, dredging and surface mining equipment industries. With approximately 4,000 members in 25 countries, activities include publication of a quarterly educational magazine, Equipment Echoes; operation of National Construction Equipment Museum and archives in Bowling Green, OH; and hosting an annual working exhibition of restored construction equipment. The 2019 show will be September 13-15 at the Museum in Bowling Green. Individual memberships within the USA and Canada are $35 for one year, $65.95 for two years and $99.95 for three years, and $55.00 US elsewhere. HCEA seeks to develop relationships in the equipment manufacturing industry, and offers a college scholarship for engineering and construction management students. Information is available at www.hcea.net, or by calling 419-352-5616 or e-mailing email@example.com.