When charging the air brake system, which of the following is a key point to remember?

The key point to remember when charging the air brake system is to only increase the throttle position to a maximum of 4 if necessary. This is crucial because it helps to ensure that the engine is operating within a safe and efficient range while maintaining adequate air pressure in the brake system.

Increasing throttle position excessively can lead to unnecessary wear on the diesel engine and may cause fluctuations in the air pressure that can be detrimental to the braking system. By limiting the throttle position, you ensure that you’re effectively managing the engine's RPM, which in turn, helps stabilize the air pressure and supports the braking system's performance.

In the context of charging the air brake system, it's important to make adjustments based upon the specific needs of the operation, and this strategy helps in maintaining control while effectively achieving the desired air pressure.