How much brake cylinder pressure develops from a 20 psi brake pipe reduction with a regulating valve set at 90 psi?

To determine the brake cylinder pressure resulting from a 20 psi brake pipe reduction with a regulating valve set at 90 psi, it is essential to understand the function of the regulating valve in the air brake system.

The regulating valve is responsible for controlling the amount of pressure that is applied to the brake cylinder based on the reduction in brake pipe pressure. With a 20 psi reduction in the brake pipe, the regulating valve will respond by increasing the pressure in the brake cylinder to a predetermined level that ensures effective braking without causing excess friction or wear and tear on the train's braking system.

Since the valve is set at 90 psi, it regulates the cylinder pressure in relation to the brake pipe reduction. In this case, for every 10 psi reduction in the brake pipe, approximately 10 psi will be developed in the brake cylinder. Therefore, with a 20 psi reduction in the brake pipe, this would yield a brake cylinder pressure of approximately 40 psi.

However, considering the settings of the valve and the typical operation of similar systems, the methodology typically yields an additional compensatory pressure when established settings like 90 psi are factored in. Consequently, with some configurations and system tolerances, the overall result reflects an expected pressure output leading