Final Answer:
The normal main reservoir pressure is in the range of 90 to 120 lbs.
Step-by-step explanation:
In various engineering and mechanical systems, including those in the field of transportation, the main reservoir pressure is a critical parameter. Specifically, in contexts like air brake systems on trains, the normal main reservoir pressure typically falls within the range of 90 to 120 lbs (pounds). This pressure range is standard for maintaining optimal functionality and efficiency of the braking system.
Main reservoirs store compressed air that is utilized to operate various pneumatic devices, such as brakes. Ensuring that the pressure is within the specified range is essential for the proper functioning of these systems, contributing to the safety and reliability of the transportation equipment.