Blaw-Knox

Blaw-Knox is one of the most prominent manufacturers of road paving equipment in the world. After Ingersoll-Rand divested of their road-making equipment operations in 2007, the company became part of Volvo of Sweden's construction equipment division.

The company was formed from 2 companies, Blaw and Knox, and eventually was purchased by White Consolidated Industries in May 1968. Originally a maker of steel concrete forms, as highway construction moved away from rigid concrete construction, the company began making highway pavers for the new method of flexible asphalt paving (tarmac). Today, the biggest distributor of Blaw-Knox asphalt pavers is Craig Plant, in London.

The company is remembered today for the distinctive Blaw-Knox Tower developed in the 1930s, a vertical medium wave radio tower distinguished by its diamond shape.

Blaw-Knox entered the construction equipment business in 1929 with concrete road building machines. In 1931 Blaw-Knox introduced a form-riding finisher for asphalt paving. By 1932 they released the first self-propelled non-form riding finisher for the placement of stones and asphalt. Until this time it had been common to pave roads using formwork on either side of the pavement. These machines were essentially a self-propelled tailgate spreader that closely followed the asphalt truck. The front wheels rode on the prepared base, while the rear drive wheels rode on the new asphalt pavement. The screed was mounted between these wheels and was able to average out irregularities. The first road widener was introduced in 1943 and other products followed, including road rollers for a brief time.

Blaw-Knox went on to establish a broad line of paving machines for the US and UK markets. Blaw-Knox subsequently sold its UK Division to Babcock; the models marketed in the UK used similar model numbers to the US versions which caused some confusion, although they carried a BK- prefix (as in BK-191) in place of the US PF- prefix. Despite the similar nomenclature, the UK/International models were often operated very differently. This was due to the very different paving methods employed, it being common in the UK to apply a deeper mat of asphalt than was common in the US resulting in a marked reduction in paving speed when compared to the US. Telescopic screeds became a very popular option giving greater flexibility when selecting changes in mat width.

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