Some useful comments taken from the Train Collectors Society Yahoo Group :
'Ottmar Beckh' or 'Beckh KG' is a firm that is relatively unknown, except for their products that are still rather common. All German sources on the www copy each other. It is known, Beckh acquired the toolings and moulds of the Nuremberg toy maker Adolf Schumann in 1939 and subsequently extended their product range of military toys. After ceasing toy manufacturing due to war efforts, Beckh restarted 1949 and from then on made a small range of very cheap clock work toy trains. All tinplate, all 0 gauge. Some sources say, the firm ceased production in 1960, some 1963 and some 1973. In 1960 they introduced a h0 scale battery train system.
All tin plate appears to haven been four-wheeled, though I remember they may have manufactured an 0-6-0 steam engine with four wheeled tender too. Beckh further was well known for their very nice lithographed signals and other miscellanious for clock work trains, like cross overs and foot bridges. We do not know when the company was founded and in fact, nor do we know for sure when it disappeared.
In the magazine 'Altes Spielzeug' , No. 4, August 2009, there was a lavishly illustrated six-page article on the 28 mm trains of Schumann and Beckh, written by Dieter Beckh, son of Ottmar. So straight from the horse's mouth, as it were. Although focussing on the 28 mm trains, it also dwells much on the Beckh 0-gauge production (as some locos were used for both the 28 mm and the 32 mm trains). Dieter Beckh states specifically that production was ended and the firm wound up at the end of 1969.
I don't think there is anything on Beckh armoured trains on the net, but the German magazine Altes Spielzeug (Old Toys) carried an article on them in their issue of April/May 2010. Otto Beckh started his firm late in 1938, buying the firm of Adolf Schumann and thereby taking over Schumann's clockwork toy train production. Beckh in 1939 produced a military train set no. 184 with an ordinary locomotive, but in mimicry, pulling three flat wagons loaded with a field kitchen, a field gun and two ambulances (this very possibly was a set already created by Schumann). For 1940 Beckh offered a set (no. 3080) consisting of an armoured locomotive pulling three wagons, two loaded with a tank and one with a field gun. This too was based on items produced by Schumann: the armoured locomotive was the same as the streamlined one produced by Schumann and (loosely) based on the streamlined locomotives of the 05-series of the German Reichsbahn, but again in mimicry. The wagons too were former Schumann products, although the tanks and field gun were bought in. Beckh also, in 1939, offered two military wagons for separate sale, one with a field kitchen and one with a field gun and munitions wagon.