Function

It only became possible with the arrival of the Bosch fuel-injection on the market. It gave the diesel engine that what distinguishes it still today, a stable power unit with minimised fuel consumption. It was first designed and built for use in trucks. Only in 1936 begun the era of the diesel passenger car. The same procedure, with an even greater time difference, was repeated later with the introduction of direct injection.

How it works

It is evidently more difficult to give the diesel engine the necessary features required for a passenger car. However, the great amount of precision work which has been done, is not obvious in the above picture.

It does, however, give us an idea of the amount of technology used at that time. One can recognise the four-cylinder by the number of the glow-plugs. With an in-block camshaft the valves will probably have been driven by rocker arms. In front (on the left) one can also see the rigid fan drive, and at the rear, (on the right) the flywheel, showing hardly any real differences to the petrol engine.It becomes important when we tackle the fuel injection pump. It already has a conveyor -manual-pump and an inspection-glass filter unit. From there a pipeline goes to the main filter on the other side of the engine and is then led back to end up on top, on the left, in the row of injection pumps. The laying of the always equally long injection pipelines was not as elegant as it became later.

The regulation is completely unusual. The centrifugal governor is notably absent, although, we know that a diesel engine must be regulated, at least when idling and at maximum RPM. If one could see the engine from the other side, we would see a butterfly valve in the air intake which is similar to the throttle valve of the petrol engine. Here the pneumatic regulation comes into play, because between butterfly valve and engine a vacuum is developed, which through a suitable membrane alone, moves the control-rod. A centrifugal governor is not necessary. Unfortunately, the control system which was built until well into the sixties, was sensitive to leakage. Within the membrane regulator, (right part of the pump) a spring pressed the control-rod in the direction of 'full load'. The vacuum provided the opposing force. If this failed because of an unwanted admission of air, the spring action would not be limited, with incalculable results for the engine. 10/08