Abstract
The braking effect afforded by the engine of a road vehicle is normally regarded as a valuable addition to the wheel brakes. The degree of braking effort of an internal-combustion engine working on the overrun depends largely on how breathing is restricted, both at induction and exhaust.
The paper clearly reveals the marked advantage of the compression-ignition engine compared with the conventional petrol engine so far as braking is concerned, largely on account of the difference in compression ratio. Out of the various methods of restricting the breathing, that of applying an ‘exhaust brake’ has a distinct advantage, particularly so in the case of a compression-ignition engine, where a resistance horsepower may be realized of about 85 per cent of the power output of the engine.
An analysis of cylinder and manifold indicator diagrams taken from a multi-cylinder compression-ignition engine, using an exhaust brake, shows the interaction of the cylinder conditions, giving an advantage when a common manifold is used.
It was concluded from the complete investigation that maximum braking effort is obtained with an exhaust brake operated with an unrestricted induction manifold. While the volume of air contained between the exhaust brake and the cylinders is required to be as small as possible, the interaction between the cylinders by using a common exhaust manifold increases the braking effect.
Get full access to this article
View all access options for this article.