US 4,593,954 AGranted

Air brake valve system

AssigneeHose America, Inc.

InventorSergio Campanini

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Abstract

An air brake control system for use in truck trailers having at each axle compressed-air brakes including spring brakes and service brakes, and each trailer being coupled to receive compressed air through an emergency (supply) gladhand and to receive service brake signals through a service (control) gladhand, the invention comprising an integrated brake valve system for each axle of each trailer, including a common valve housing; a spring brake valve cluster having a non-return check valve connected to receive and pass air pressure from the emergency gladhand and to deliver it directly to the spring brakes and an air pressure responsive shuttle operative to open the check valve whenever the emergency line pressure falls below a predetermined spring brake isolation pressure above which the spring brake holding pressure is not affected by fluctuations of the emergency gladhand pressure; and including an air tank supply valve cluster connected between the emergency gladhand and the tank and operative to sense pressure in the emergency gladhand and to open at a tank-filling threshold pressure above the predetermined spring brake isolation pressure to pass air to the tank and having a tank protecting check valve to prevent backflow of air from the tank; and including a pressure amplifying service brake relay valve cluster connected between the tank and the service brakes to supply and modulate air to the latter responsive to variations in the service gladhand pressure.

Claims20

Dependent claims

In a tractor and trailer rig of the type wherein the tractor includes a source of air under pressure and a tractor protection valve that will supply air to the trailer whenever the air pressure is above a minimum supply line pressure and wherein the tractor includes low-pressure warning means operative to warn the driver whenever the air pressure in the tractor is below a predetermined threshold level, and wherein each trailer includes at each axle brake means including compressed air tank means and including spring brake means having actuator means which are compressed-air operated to hold the spring brake means OFF and including service brake means having actuator means which are compressed-air operated to apply the service brake means, and wherein each trailer is coupled to receive compressed air through an emergency gladhand and to receive a service brake air pressure control signal through a service gladhand, a brake valve system for each axle of each trailer, comprising:

(a) valve housing means;
(b) a spring brake valve cluster comprising a non-return check valve connected to receive and pass air pressure from the emergency gladhand and to deliver it directly to the spring brake actuator means, and the spring brake valve cluster further including means operative to measure the air pressure in the emergency gladhand and to open the check valve whenever the measured pressure is below a predetermined spring brake isolation pressure which exceeds said minimum supply line pressure but is low enough to actuate said driver warning means, whereby to protect the spring brake actuator means and maintain its pressure at the maximum operating emergency gladhand pressure until the latter falls below said isolation pressure;
(c) an air tank supply valve cluster connected between said emergency/supply gladhand and said tank means and operative to fill said tank means, the supply valve cluster comprising a pressure responsive valve operative to sense pressure in the emergency gladhand and to open at pressures above said threshold pressure whereby to pass air to the tank means, and the supply valve cluster further including a tank protecting check valve interposed between the pressure responsive valve and the tank means and continuously operative to prevent backflow of air from the tank means toward the emergency gladhand;
and
(d) a service brake relay valve cluster connected between the tank means and the service brake actuator means to supply and modulate air to the latter from the tank means in response to variations in the level of the service brake air pressure signal.

2 more elements

In a truck brake system having brake means including spring brake means having actuator means which is compressed-air operated to hold the spring brake means OFF and including service brake means operative above a minimum service brake pressure to apply the service brake means and the system including a supply line through which it receives compressed air and including a source of a service brake air pressure control signal, spring brake valve means comprising:

(a) valve housing means;
(b) a normally operative non-return check valve in the housing means and connected to receive air pressure from the air supply line and to open and deliver it directly to the spring brake actuator means to maintain the pressure in the actuator means at the highest level attained by the pressure in the supply line, and being operative to close when the air pressure in the supply line is less than the pressure in the actuator means to prevent back flow of air pressure into the supply line;
and
(c) shuttle means in the housing means operative to measure the air pressure in the supply line and operative whenever the measured pressure is above a predetermined spring brake isolation pressure which exceeds said minimum service brake pressure but is just sufficient to hold OFF said spring brake means to move away from contact with the check valve, and the shuttle means being operative when the air pressure is below said predetermined spring brake isolation pressure to move into contact with the check valve and hold it open, whereby to couple the spring brake actuator means directly to the supply line to have its pressure modulated by fluctuations in the supply line.

1 more element

In a truck brake system having brake means including air tank means and including service brake means which is compressed-air operated to apply air from the tank means to service brake actuator means and the system including a supply line through which it receives compressed air and including a source of a service brake air pressure control signal, service brake valve means comprising:

(a) valve housing means;
(b) a service brake valve cluster in said housing means and including a piston slidable in a bore in the housing means and axially moveable between a service brake-vented position and progressively-increasing brake-applied positions, the bore on a first side of the piston being connected to receive a service brake control signal whereby the piston is displaced toward a brake-applied position in response thereto;
(c) the service brake cluster further including a normally closed slide valve in a bore in the housing means communicating with the tank means and actuatable to control the flow of air from the tank means to a chamber in the housing means communicating with the second side of the piston and with the service brake actuator means, the slide valve being contacted and actuated by the second side of the piston when in a brake-applied position to introduce into the chamber and against the second side of the piston pressure from the tank means opposing the service signal pressure on the piston;
(d) and the piston having an extension portion on its first side isolated from the service brake control signal pressure and operative to reduce the effective area of the first side of the piston on which the service brake air signal acts sufficiently so that said effective area closely approaches the effective area on the second side of the piston on which the opposing air pressure acts when the second side of the piston is in contact with the slide valve, whereby the air pressure on the second side of the piston is at least equal to the air pressure on the first side of the piston when the forces of these pressures are in balance.

1 more element

Dependencies are inferred from the claim text.