Company History - from an old photographic album (No.1)

Tomizo Kohara, the founder of Kohara Gear, started production and sale of change gears to be used for a lathe in 1937.
In those days two types of lathe was mainly used. One was "English-type lathe and the other "American-type lathe." Tomizo standardized change gears to be installed to a lathe (both English-type and American-type) to be used for the processing of screws, and put them on sale. In order to proceed with the standardization he devised the adoption of generally acceptable dimension of change gears' pitch, bore, keyway, facewidth, etc., to match each size of lathe. The compatibility and "off-the-shelf" handiness (those are the hallmarks upon which Kohara Gear was built and KHK is pursuing) really appealed to his customers and his change gears sold very well. This change gear was the very thing that became the origin of KHK stock gears.
Kohara Gear's change gears were also used for machines other than lathe as a machine element. Kohara Gear went further into standardizing other types of gears, such as bevel gears, worm wheels, racks as the company grew. To put the standardization into practice Tomizo and his staff studied the commonalities of custom gears they produced - custom gears for drilling machine, milling machine, opening and closing device of sluice gate, farm implements, etc.

* Click on the photos for enlargement

The rotary motion transmitted through a flat belt to a stepped pulley, is sent to two directions: One to a set of change gears, then to a lead screw, then to a tool rest, then to a turning tool for thread. The other to a back gear for deceleration, and then to a screw in the process of making.
The pitch of the screw in process is equal to the distance the tool rest with the turning tool travels while it (the screw in process) makes one turn.
A set of change gears is comprised of 23 pieces, the number of teeth of which is 20, 25, 30, 35, 40 (2 pieces), 45 ····· 120, and 127. DP25~5 were standardized and were on sale.
The photo on the left: Gear blanks (casting) are seen piled up on the far left. The photo on the right: Nobuharu Kohara (center) and Seiji Kohara (right). Gear blanks (casting) are seen heaped on the right. On the bed of a handcar in the background, gear blanks are seen piled up.
The photo on the left: A row of small hobbing machines for cutting gear teeth of change gears. The photo on the right: A wooden factory building bearing a sign on the wall "KOHARA HAGURUMA KOJHO" meaning Kohara Gear Workshop.
The photo on the left: A Nissan Datsun truck bearing a sign "KOHARA KIKAI HAGURUMA KOJYO (Kohara Machine/Gear Factory), Change Gears, Nishikicho, Kawaguchi, and a mark "T K" (Tomizo Kohara's initials), T K being the predecessor of KHK logo. The photo on the right: The Nissan Datsun truck standing in front of an imposing edifice. (Does anyone know of the name of this building and of the time the photograph was taken? Please let us know.)

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