Carl Kaelble Z
2 models in this series
Carl Kaelble Z series: heavy tractor units from Backnang with crude-oil engines, from the Z 1 Suevia AD 17 to the Z 4 S, 8.8 to 44.1 kW from one- to four-cylinder units
Carl Kaelble, based in Backnang, was a German maker of heavy tractor units that specialised in rugged crude-oil engines – hot-bulb units running on cheap, hard-to-ignite crude oil rather than petrol or diesel, built for hard work in construction and haulage. This page collects the marque's Z series, from the Z 1 Suevia AD 17 to the Z 4 S; the Z stands for Zugmaschine (tractor unit), with the attached number denoting the size class.
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The register lists 2 versions from 8.8 to 44.1 kW from one- to four-cylinder units of 2,454 to 9,748 cm³ displacement, running at 1,000 rpm. One of the recorded machines weighs 4,300 kg at a length of 3,500 mm, a width of 1,950 mm and a height of 2,150 mm.
Tractor units of this kind handled heavy road haulage in the first half of the twentieth century before conventional diesel-engined lorries displaced them; Kaelble also built heavy dumpers and construction machinery alongside them. Crude-oil technology freed the vehicles from expensive fuel but demanded careful pre-heating of the hot bulb before starting.
When buying a used example, check the condition of the hot bulb and cylinder liners, the tightness of the cooling system, the state of clutch and gearbox, and corrosion on the frame and tow hitch. Parts for these early crude-oil engines are scarce and mostly available only through specialist collectors and restoration workshops, and a solid understanding of hot-bulb technology is essential when restoring one.
Sources: SpecCodex register, model data: Carl Kaelble Z
Models
Tractor in 3D section
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