What is referred to as the cranking speed of an engine?

The cranking speed of an engine is specifically the speed required to start a diesel engine. This speed is critical because it helps ensure that the engine has enough rotational force to achieve a proper compression and to allow for the fuel injection system to operate effectively. For diesel engines, which rely on high compression for ignition, reaching this cranking speed is essential to initiate the combustion process and get the engine running. If the engine does not achieve this speed, it may struggle to start or fail to start altogether.

Options that pertain to acceleration or fuel ignition do not directly define the cranking speed; instead, they describe different aspects of engine operation and performance. The speed limit of the engine refers to the maximum operating RPM and does not relate to the initial starting requirements.