Patented Paver Features Many "Firsts"

Sept. 28, 2010


Power Curbers' Curb King 6500 held a patent for the first four-crawler slipform curb-and-gutter machine.Tables:

The Curb King 6500 was the first slipform paver manufactured by Power Curbers, produced from 1970 through 1979. Billed as an electronically controlled slipform paver for curb and gutter, the 6500 was the first to pour in the offset position.

According to Power Curbers, which celebrates its 50th anniversary this year, the 6500 held a patent for the first four-crawler slipform curb-and-gutter machine. The footprint for the 6500 served as the model for later machines, notably the 5500 and the 5700.

The 6500 was also the first machine to turn a 15-foot radius "with regularity," the company says, although initial marketing claimed radii as tight as 20 feet. The four individual crawlers enabled the tight turning, which eliminated a separate crew for hand-forming these pours.

Labor cost-saving weighed heavily into the development of the 6500. Contractors called for a curb-and-gutter machine that did away with forms, gave high daily production, and worked off a string line. The 6500 promised 50-percent labor savings, with hand finishing only necessary where joints were to be cut. A crew of seven could produce 2,000 to 3,000 feet at 8 to 18 feet per minute.

An electronic steering sensor guided the front crawlers from true line on both straight and radius work. Two electronic elevation sensors controlled their respective crawlers for grade and slope control. The controls worked off of a string line.

Material was gravity-fed into the 6500 directly from the transit mix truck to the hopper. Three high-speed internal vibrators densified the concrete before being shaped by the slipform mold.

Power Curbers started in 1953 as a manufacturer of curb-extruding equipment. John S. Henderson and E.L. Hardin founded the company in Salisbury, N.C., and began manufacturing an asphalt-extrusion machine invented by Bill Canfield, an employee of the North Carolina Department of Transportation.

In 1957, Roy Smith joined the company and applied the original invention to curb-and-gutter work. This patented machine enabled Power Curbers to take part in the greatest road-building project of American history: the construction of the Interstate highways.

Information provided by Power Curbers. If you're interested in historical machines, consider a membership in the Historical Construction Equipment Association. Visit HCEA's website at Also visit for past Iron Works features and for an opportunity to submit photos of your oldest machines to our new Gallery.

Basic Specifications: Curb King 6500Curb-and-gutter base widthup to 36 in.Curb-and-gutter section heightup to 15 in.Water tank20 gal.Length167 in.Width60 in.Height72 in.Net weight5,600 lb.