Modulator valve

A modulator valve for installation in a braking system of an auxiliary axle, the valve having a valve body comprising:

• a control port for receiving a brake application pressure signal;
• a lift port for receiving a pressure signal from a lifting system for the auxiliary axle;
• a ride port for receiving a pressure signal from a suspension system for the auxiliary axle, with the suspension system including ride springs;
• a supply port for receiving a pressure signal from a supply reservoir;
• a delivery port for delivering a pressure signal to the anti-lock brake system of the auxiliary axle;
• a piston, spring, and valve arrangement operatively connected to the control port and the lift port and configured and dimensioned such that when the auxiliary axle is lifted no brake application pressure signal is allowed to pass to the delivery port, and when the auxiliary axle is not lifted a brake application pressure signal is allowed to pass to the delivery port;
• a modulator piston operatively connected to the control port, supply port, and delivery port, wherein, the modulator piston has an upper surface separated into distinct areas configured to receive a percentage of the brake application pressure signal, and a lower surface of the modulator piston operatively connected to the supply port and the delivery port such that when a brake application pressure signal is applied to the upper surface of the modulator piston, a modulated pressure signal is delivered through the delivery port to the anti-lock brake system of the auxiliary axle;
• a modulator piston operatively connected to the control port, supply port, and delivery port, wherein,
• the upper surface of the modulator piston is separated into distinct areas configured to receive a percentage of the brake application pressure signal,
• the lower surface of the modulator piston is 100% of the sum of the areas of the upper surface of the modulator piston, and
• the lower surface of the modulator piston is operatively connected to the supply port and the delivery port such that when a brake application pressure signal is applied to the upper surface of the modulator piston, a modulated pressure signal is delivered through the delivery port to the anti-lock brake system of the auxiliary axle;
• a second piston, spring, and valve configuration operatively connected to the control port, ride port, and modulator piston, wherein,
• when the pressure signal from the ride springs is less than a certain threshold X1, a brake application pressure signal is only delivered to a certain distinct area of the upper surface of the modulator piston;
• when the pressure signal from the ride springs is greater than a certain threshold X1, but less than a certain threshold X2, the brake application pressure signal is delivered to more than one distinct area of the upper surface of the modulator piston;
• and
• when the pressure signal from the ride springs is greater than a certain threshold X2, a brake application pressure signal is delivered to more than two distinct areas of the upper surface of the modulator piston.