To improve on cross country ability, these early "Kubelwagens" had large section tyres, strengthened springs, and lower axle ratios than their commercial equivalents. During the 1930's, this type of vehicle saw ever wider use with the German army and was one of its most characteristic and distinctive types. These "Kubelwagens" were used as light gun tractors, staff cars, radio cars, command cars, artillery survey vehicles, and signal line layers, as well as serving as personnel carriers for motorized units. Trials held in 1930 had established that the car chassis made by Daimler-Benz, Adler and Wanderer were the best, and these makes predominated in service.
From 1933, when the National Socialist took power and began overt re-armament of the German forces, there was an expansion on an increasing scale with mechanisation of the greatly enlaged army among priority schemes. At that time the various cars on adapted commercial chassis were categorised as follows: Leichte Personnenkraftwagen (light passenger car) approved makeup to 1500cc engine capacity. Mittlerer Personenkraftwagen (medium passenger car) approved make up to 3,000cc engine capacity. Schwerer Personenkraftwagen (heavy passenger car) approved make up to 3,000cc engine capacity.
The light passenger car types were each given a designation according to their intended purpose. Thus Kfz (kraftfahrzeug) 1 was the designation for the basic light personnel carrier; Kfz 2 designated a light signals car (Kraftkahrzeug motor vehicle). The medium vehicles were designated similaryly from Kfz 11 upwards according to function. In the heavy class only the Kfz 21 heavy cross country personnel carrier was produced, as this was the last type to be approved and ordered. It entered service in 1937 and was based on the Auto-Union/Horch EFm chassis, remaining in production until 1940 (after Austria was annexed, the Steyr 1500A was also built to this "heavy" requirement, however also designated Kfz 21). The Auto-Union/Horch EFm model had a V-8 80 hp engine and four wheel drive. Because of its length it had three rows of two seats, seating six men in all. Spare wheels were carried on the side panels flanking the first and second rows of seats. The ordinary commercial tourer car on which the military "kubelwagen" a senior officer's staff car. The Kfz 21 was described in German as the "Schwerer gelandegangiger personenkraftwagen (6-sitzer)" heavy cross country passenger car (6 seater). It had the normal sort of open Kubelsitzer body and a folding canvas top. Overall length was 15 ft 11 inches.
Field car production with tis chassis started late in 1938. Externally all Auto-Union/Horch heavy cars looked alike irrespective of actual chassis model, however. By 1940 the chassis had been simplified considerably, and the Berlin Ford factory was also by then engaged in production. Ford built vehicles had a Ford 3.6 litre V-8 78 hp engine in place of the Horch unit. The late 1940 models lacked recesses in the body and chassis mounted support arms for spare wheels. Production ceased in 1941 in favour of a new scheme under the Schell-Programm which sought to rationalise car production completely. In this scheme the heavy car shared the chassis of the 1.5 ton light truck. Auto-Union/Horch heavy cars remained in service throughout World War 2, however, and were among the most common of German vehicles on every front. The Auto-Union/Horch on the heavy passenger car chassis was used in several roles, and though the layout of the open body followed the old Kubelsitzer idea, all but the very earliest had the added refinement of metal side doors rather than canvas side screens. The following were among the types based on this chassis: Fernsprechkraftwagen (Kfz 23) Telephone Truck. Leichter Scheinwerferkraftwagen I (Kfz 83) Light Searchlight Truck I Leichter Scheinwerferkraftwagen II (Kfz 83) Light Searchlight Truck II Protzkraftwagen (Kfz 59: Limber (or towing) Vehicle for Light Guns. Mannschaftskraftwagen (Kfz 81): Light AA Vehicle (some with 2 cm Flak Gun mounted) All the above had the open body but differed in function and, in some cased, internal stowage and equipment. In addition, the following were built on the chassis: Sanitaetskraftwagen (Kfz 31): Ambulance Verstarkerfraftwagen (Kfz 24): Maintenance Truck Both of these had a closed van type body.
German Horch Type 1a Kit - CA152