| Among the numerous passenger car-models constructed before the First World War at the Daimler-Motoren-Gesellschaft, the Daimler-Knight types were looked upon as special. They were driven by valveless slide-valve engines going back to an invention by the American Charles J. Knight. Paul Daimler, appointed head of the design bureau in 1907, had acquired the licences for the production of the Knight-engines in 1910 and immediately develop three passenger-car types with the new driving principle. The series-production of the 16/40 hp with 4-litre-4-cylinder-engine still started in 1910 whereas another two four-cylinder-models, the 10/30 hp and the 25/65 hp were not produced before 1912.
At that time advantages and disadvantages of the Knight-construction were discussed controversially by automobilists and engineers. Undisputed advantages were the new system_s smoothness and refinement exceptional at that time. Moreover Knight-engines performed clearly better in the speed ranges from about 500 to 1,500 r/m than conventional aggregates of the same size.
On the other hand slide-valve engines demanded a good deal of time and energy in terms of design and production technology as well as a highly sensitive way of handling them. A particularly critical point was the correct lubrication of the cylinder- and slide-valve running surfaces which very often was not guaranteed with the lubricants of that time - especially when maintained insufficiently. This aspect became more and more problematic in the speed-range over 1,600 r/m in which the slide-valve engine was not superior even in its specific way of performance.
The maximum speed ranges that could be realized around 1,750 r/m limited the top speed to about 80 km/h so that the development potential and the practical use of the Knight-motor were limited, at least in the long run.
Despite this there were confirmed proponents of the Knight-engine among the customers of the Daimler-Motoren-Gesellschaft, a fact impressively documented in a number of produced vehicles of more than 5,500 as well as a period of production of no fewer than 14 years. The types 10/30_hp and 25/65 hp were only produced up to 1915, the 4-litre model, on the other hand, remained in the programme until 1925. The engine's performance of this type could be raised from original 40 hp to an interim 45 hp in 1913 and, finally, to 50 hp in the last year of production. |