Which position involves sealing the ports between the reservoir and the hydraulic circuits?

The position that involves sealing the ports between the reservoir and the hydraulic circuits is referred to as the 'At Rest Position.' In this position, the brake system is static, meaning that no pressure is actively applied to the brake components. The design of brake systems requires that the ports remain sealed when the brakes are not engaged to maintain hydraulic pressure within the system and prevent fluid leakage.

This sealing is crucial as it ensures that the hydraulic fluid remains contained within the circuit, allowing for quick response times when the brakes are applied. In contrast, the other positions involve active engagement or application of the brakes, which would not prioritize sealing the ports in the same manner. Therefore, it is the 'At Rest Position' that specifically focuses on maintaining the integrity of the hydraulic system by effectively sealing the ports.