KH-50

During World War I, the well-known German designer Ing.Volmer (who worked on German tank projects A7V, LK-I, LK-II) developed a combined chassis. It was a combination of tracked and wheeled chassis. Its design used the platform of an economic tractor Hanomag WD-50 PS. The advantage of such a combined chassis was that in the case of movement in difficult terrain, the vehicle used the tracked chassis; in the case of movement on a paved surface (road), the wheeled chassis was lowered and the machine moved on wheels. Movement on wheels was faster and more economical.

The licence for this combined chassis was purchased by the Czechoslovak military administration in 1923 and the Breitfeld-Daněk company, which already held the licence for the farm tractor Hanomag WD-50 PS, was commissioned to develop and build two prototypes of the combined chassis.
Breitfeld-Daněk of Prague was to build the vehicles, the transmission, rear-wheel drive and tracks were to be supplied by Laurin & Klement of Mladá Boleslav, and Kopřivnická vozovka a.s. (Tatra) supplied the steering and front axle with wheels. The K3 engines were purchased from Hille of Dresden.
The tractors were completed in 12/1924. Their serial numbers were 2001 and 2002. The first driving tests were started on 7/1/1925. After their completion the tractors were modified.
On 5.3.1925 the vehicles were officially taken over by the automobile department of the artillery. The soldiers paid a total of 1.651.820.- CZK to the manufacturer.
Immediately after taking over the vehicles pass driving-technical tests. These include driving 3,000 km on the road on wheels and 500 km on tracks, 1,000 km on wheels and 200 km on tracks while pulling the gun carriage 210 mm Maziara vz. 18. In addition, he has 200 hours in the field maneuvering with the gun carriage in tow. Due to the complicated and immature design, the tractors were often under repair and so military trials dragged on until 1926.
The military administration planned an order for 100 vehicles. The Tatra and Laurin & Klement companies stated in 5/1925 that they were able to deliver the components within three months.
In 6/1926 the MNO allowed the export of these vehicles on condition of a 30% share of the manufacturers' profits as compensation for development and licensing rights.
On 6/24/1926, the MNO submits a proposal to the VHO to rebuild one tractor for further testing. At that time the vehicles are located in České Budějovice.
In 1929, one tractor in České Budějovice is cancelled. The Automobile Section of the Artillery requested to keep the parts from the cancelled tractor for teaching purposes. On 11.1.1930 it was granted and all the material remained at the department as teaching material. Later on, the tractor engine was used to pull targets at the Brda tank shooting range.
In 1930, the MNO bought spare parts made for these tractors from Škoda and ČKD. The takeover of the parts from Škoda was refused due to the vehicle not being introduced into the armament, but the parts produced by ČKD (models and production aids) were purchased and taken over on 9/1933 at ČKD Slaný. Among the so-called models was the body of the combat assault vehicle KH-60.

The prototypes underwent tests within Artillery Regiment 305 under the supervision of the Military Technical Institute. The results of the tests were not satisfactory and therefore further development took place, which resulted in the K.H.-60 type.

The machine had no upper hull, the engine located at the rear of the platform was covered by thin plating. The driver and his compartment were to be protected from the weather by a canvas roof. The vehicle carried auxiliary ramps on the side of the tracked part of the chassis, with the help of which the transition from the wheels to the tracks and vice versa was carried out. The whole operation of the transition took the two men about 5 minutes. The changeover was carried out mechanically by means of a crank.

Ivo Pejčoch - Československé pásové dělostřelecké táhče 1918-1950, Ares publishing house, ISBN 978-80-86158-52-5
Ivo Pejčoch, Oldrich Pejs - Obrněná technika 6, Central Europe 1919-1945 Part I, ARES publishing house, Prague 2005, ISBN 80-86158-46-2
Vladimír Francev, Charles K. Kliment - Czechoslovak Armoured Vehicles 1918-1948, ARES Publishing House, 2nd edition, Prague 2004, ISBN 80-86158-40-3
https://rotanazdar.cz/?p=9390&lang=cs

Photos kolohousenky KH50 of the exercises test battery, 305 artillery regiment in 1925..

Dear,
I put an excerpt from the defunct czechoslovak patent file no. 23431 from 1927 with the title: the wheel Suspension of automotive vehicles with a combined drive wheel and housenkovým. It is interesting that in patents with numbers: 21576, 21577, 21578, 22123 and 23431, not the author, only here is the link to the prague Ministry of national defense.

I assume that the patents were due to the tests of the KH-50 and have been applied in the manufacture of KH-60.

Source
Patent no. 21576: Drive automotive vehicle with a combined drive wheel and housenkovým, 1927
Patent no. 21577: Gears of automotive vehicles with a combined drive wheel and housenkovým, 1927
Patent no. 21578: the Brake of automotive vehicles with a combined drive wheel and housenkovým, 1927
Patent no. 22123: Management of automotive vehicles with a combined drive wheel and housenkovým, 1927
Patent no. 23431: the wheel Suspension of automotive vehicles with a combined drive wheel and housenkovým, 1927.