The advent of the motor vehicle made it necessary to improve roads on a massive scale. Road surfaces of macadam, gravel, brick, logs or just plain dirt were inadequate for the new demands placed on them. Heavily laden trucks with solid tires were especially brutal, and in one instance a single truck loaded with supplies destined for the World War I battlefields pulverized a road surface in Delaware.
Asphalt pavement was one of the solutions, and with the solution came the development of machines to place it. At first, asphalt pavement was laid by roadmixing with graders, or spread by a form-riding screed as was concrete pavement of the time.
In the fall of 1929, Barber-Greene Co. of Aurora, Ill., began working on a better way to produce and place this material. Barber-Greene manufactured conveyors and bucket loaders, and the company was approached by George Craig and Hugh Skidmore of the Chicago (Asphalt) Testing Laboratory about a way to adapt the bucket loader to improve gravel roads to asphalt paving. Although their idea didn’t work, it introduced Barber-Greene to the industry.
The seeds planted by Craig and Skidmore took root in the form of the Travel Plant. This machine was a variation on the idea of roadmixing asphalt pavement; but instead of mixing the raw materials repeatedly on the road’s surface, a modified bucket loader elevated the windrowed material from the road surface into a small pugmill carried on the loader. The pugmill discharged the mix to a form-riding, 20-foot-wide spreader that was towed by the loader/mixer. The mixture was controlled by the metering of aggregates and bitumen, a concept that was not available with grader roadmixing.
The Travel Plant was first used successfully on a project at Rolla, Mo., in 1931, and the result was superior to the pavement produced by graders. Shortly after its introduction, the Travel Plant was redesigned, with the pugmill and metering apparatus moved from the loader to a separate trailer.
Barber-Greene, under the leadership of co-founder Harry H. Barber, also began developing the first modern asphalt paver. Barber saw the superiority of hotmix material for asphalt paving and wanted to design a fully mechanized machine capable of handling it. The project proved difficult and costly, and was intermittently suspended due to the hardships of the Great Depression, only to be revived each time at the insistence of Barber-Greene’s sales staff. An early version was tested in 1934, and shortly the Model 879 asphalt paver was introduced.
The 879 was crawler-mounted. The asphalt mix was received and carried in a front hopper, passed under the machine by means of a slat conveyor, distributed across the roadway by a screw conveyor, consolidated by a vertical tamping bar that vibrated at 1,200 strokes per minute, and finished by a rear screed. The machine’s design and slow speed compensated for irregularities in the roadbed, and it automatically produced a level mat of uniform thickness.
The 879 held several patents and was designed for simplicity and longevity. It was hugely successful, to the point that by the late 1930s Barber-Greene had become synonymous for asphalt pavers. It was upgraded in 1940 to the 879A, which remained in production into the 1950s, and all subsequent crawler asphalt pavers can trace their design to the 879 and 879A. Barber-Greene and other companies also continued to produce roadmixers for some years for coldmix paving and other specialized applications.
The Historical Construction Equipment Association (HCEA) is a 501(c)3 nonprofit organization dedicated to preserving the history of the construction, dredging and surface mining equipment industries. With more than 4,000 members in 25 countries, activities include operation of National Construction Equipment Museum and archives; publication Equipment Echoes, from which this text is adapted with additional material from Our First Five Decades, published by Barber-Greene in 1966; and hosting an annual working exhibition of restored construction equipment. Individual memberships are $32 within the U.S. and Canada, and $40 elsewhere. Information is available at www.hcea.net, 419.352.5616, or email@example.com.