The plumbers Wilhelm Krauss, Johann Mohr, Emil Bell and Mathias Lechner established on the 1st of January 1895 a factory for production of sheet metal toys. The emphasis of the production was with simple steam engines and hot air engines as well as steam accessories. The toys where marketed by large publishers such as Ullmann & Engelmann, Fürth, A. Wahnschaffe, Nuremberg among others. In addition to this, they were also looking for collaboration with other steam toys manufacturers. For Bing were steam engines and a few hot-air engine types manufactured, but also series of simple steam accessories. There are also indications on business relationships with the companies Carette, Falk and Schoenner.

Stylistic characteristic of the K.M.&Co. steam engines and hot air engines is the shaping of the cylindrical sheet metal parts. Boiler covers, steam domes, chimney base and -crowns were of playful plasticity and eminence, which caught the historicism in the machine architecture.

Only a few years after the company was established - around 1901 - the partners obviously came into disputes that led to the separation. Krauss, Mohr and Lechner retired from the company, which continued under the old name for a short time by Emil Bell and its attorney Anton Ross, a Nuremberg businessman. The company name K.M.&Co. disappeared in 1903 and was changed to E. Bell & B. Breitenbach. The company existed under this name until 1919. It is unclear whether further toys were produced or whether the production was reoriented into other areas of sheet metal goods production, such as household wares and others. In 1905 E. Bell and B. Breitenbach received two patents on water filler devices for toy steam boilers (D.RP. 160614 and 160615). It is not known whether these were realized in a model machine.

Directly after leaving the company W. Krauss and J. Mohr established a new toy company, Mohr & Krauss, based in Hochstraße 23, Nuremberg. Probably a large part of the tools had been taken over from K.M.&Co., as there were lots of stylistic similarities between the toys from the two companies. However, it must be said that the precise assignment of some steam engines and accessories is unclear during the transitional phase of both companies. Identification of the toys is difficult due to the above, and the fact that their toys are only rarely noticed, which especially applies to the steam accessories. A consistent characteristic of K.M.&Co., M&K to the successor company WK (their trademark is almost always attached to the toys) seems to be the four-spoke drive wheel of the steam accessories. It is not known whether some other manufacturer copied this wheel in its simple, severe geometry.

There are three known patents by M&K, however none related to steam toys. Besides steam engines, hot air engines and steam accessories the factory produced sheet metal toy cranes and vehicles (cars) with flywheel and feather drive. Even before the First World War, it seems that the production of steam engines and hot air engines have been abandoned. The focus of the production remained on steam accessories, of which many were a mix of lithography and hand-painted. At the 28th of December 1917 W. Krauss became the sole possessor of M&K, probably due to the death of J. Mohr. After the war, the production of tin toys was continued, still under the name M&K. More detailed data over the number of employees, the production volume, etc. could not yet be determined. However, the main building at Hochstraße 23 (still preserved) and the remaining of the factory buildings indicates a staff of approximately 40-60 people.

On the 19th of April 1923, the company ceased to exist under its previous name and now became Wilhelm Krauss. The headquarters did not change. The focus of the production program was still steam accessories but it shifted significantly towards simple and cheap goods. An entire series of primitive accessories was produced for J. Falk and was offered in their catalogues from 1925. From about the mid-30s, a revised trademark was used in parallel with the trademark used since 1923. Both trademarks always appeared as lithographic illustrations.

The company W.K went out of business on 23rd of June 1938 under circumstances that still need an exact clarification. Political reasons are not to be excluded. The tools and machines were taken over by the Metallspielwarenfabrik Keim & Co., Nuremberg.