History of pipe belt conveyors

A pipe belt conveyor encloses its load inside the moving belt. The belt opens at the loading and discharge ends and closes into a tube along the conveying route. Its history spans early enclosed-belt inventions in the 1930s and the later development of the overlapping belt used by the commercial Japan Pipe Conveyor system. Johns, US2013242A; Hashimoto, GB2061853A.

Early tubular belt patents

Henry Stinson Johns developed several early forms of enclosed conveying. His US2013242A, Conveying mechanism, was filed on May 12, 1934 and granted on September 3, 1935. It described two flexible, trough-shaped belts travelling face to face to form a moving tube. US2108488A, Tubular belt conveyer, granted on February 15, 1938, addressed opening the tube to discharge material and described both paired belts and a single tubular belt with a longitudinal slit. These records establish that tubular-belt concepts were already patented before 1940. US2013242A; US2108488A.

Johns' US2212024A, filed on September 12, 1939 and granted on August 20, 1940, concentrated on a grooved pulley that opened a single slitted tubular belt for loading or discharge. It explicitly referred to his earlier patents. The 1940 patent therefore belongs to an existing sequence of inventions. Its preformed, ribbed tube differed from the later JPC belt with overlapping edges. US2212024A.

Development of the commercial pipe belt

Hashimoto's Japanese development began in 1959, with a basic design and patent applications reported by 1964. Full-scale trials in 1970 failed. Bridgestone joined the belt-development work in 1975; successful straight, level trials followed in 1976, then curved and steeply inclined trials in 1977. The central problems were maintaining the pipe shape, controlling twisting and arranging the supporting rollers. Buchanan, Beltcon 3, 1985, printed pp. 2–3.

Kunio Hashimoto's US3338383A, Pipe conveyor, was filed on September 21, 1965 and granted on August 29, 1967. It used a slide fastener to close the belt and a chain attached along the belt to transmit the driving force. This was an early stage of his development: its closure and drive arrangements differed substantially from the subsequent commercial overlapping-belt system. US3338383A.

The later principle appears in JPS5574905A, filed on November 28, 1978 and published on June 5, 1980. Its belt's elastic tendency brought the edges together into an overlapping tube. Hashimoto's British application GB2061853A, filed on October 30, 1979 and published on May 20, 1981, described a belt with its own tendency to roll closed, overlapping edges and surrounding support rollers. It also explained the difficulties caused by material fouling zipper closures. These records document the development of the recognisable overlapping pipe belt. JPS5574905A; GB2061853A.

Improvement continued after commercial introduction. Hashimoto's US4402395A, granted in 1983, addressed twisting by changing the angle of correction rollers. Bridgestone's US4572359A, granted in 1986, addressed belt construction, introducing layers with low friction at the overlap. Together, these patents show how pipe conveying depended on both the supporting machinery and the behaviour of the belt itself. US4402395A; US4572359A.

First commercial installations and overseas adoption

The first commercial JPC installation was at Kitakyushu Sand Co-op, Japan, in 1979. It comprised two 300 mm diameter conveyors, 20 m and 28 m long. Buchanan reported them still operating successfully in 1985. Japan Pipe Conveyor Company was formed in 1982. Buchanan, printed p. 3.

Bateman in South Africa became an early overseas licensee; CKIT's historical account identifies it as the first license partner to market the system successfully outside Japan. Other licensees included Koch in Germany, Noyes in France, Dosco in the United Kingdom and Krupp Robins in the United States. CKIT, The History of Pipe Conveyors. By September 1985, Buchanan reported 11 commissioned conveyors in South Africa, seven installations in Taiwan, two in Australia and two in Europe. Buchanan, printed p. 2.

British Coal's early projects illustrate adoption beyond Japan. At Wearmouth Colliery, an 85 m trial conveyor followed a May 1988 installation decision. The trial had a 300 mm pipe diameter and a 300 t/h capacity; its success led to an extension to 300 m, commissioned in May 1989. Experience at Wearmouth supported approval of the 1,658 m Westoe–Harton conveyor, which carried colliery discard to Harton Staithes at a rated 300 t/h. It began carrying the colliery's discard on August 7, 1989, while commissioning and tracking work continued. These are documented early British applications, with distinct dates for the trial decision, extension commissioning and Westoe's start of material transport. Day, Beltcon 7, 1993, printed pp. 4–5 and 10.

Selected patent chronology

The dates below distinguish applications from publication and grant. The records cover precursors and later improvements; they do not all describe the same conveyor construction.