A brake adjustment monitoring system, including a sensor having a movable actuator for mounting in or on a brake service chamber and circuitry which responds to the actuator's position to generate a display indicating whether the brake is correctly adjusted (after actuation of the brake). In preferred embodiments mounted in a motor vehicle having several brake assemblies each including a service chamber, a sensor is mounted in each service chamber, and a display panel mounted to the dashboard indicates the status of each brake assembly or each pair of the brake assemblies. Preferably, each sensor is designed for use with an air brake assembly including a service chamber, a push rod having one end outside the chamber and another end in the chamber, and a slack adjuster connected to the push rod's outer end. In response to air pressure in the service chamber (produced in response to actuation of the vehicle's brake pedal), the push rod's outer end translates away from the chamber (with an adjustable maximum travel distance). One sensor is mounted through the wall of the chamber, with an actuator positioned in the chamber in the path that a brake element (e.g., a diaphragm plate connected to the push rod) follows when the brake is applied. If the brake is improperly adjusted, the brake element travels sufficiently far, with full brake application, that it engages the actuator (thereby causing the display to indicate improper adjustment of the brake assembly). If the brake assembly is properly adjusted, the brake element does not engage the actuator (and the display indicates proper adjustment of the brake assembly).

A vehicle testing device and method are provided whereby a mechanic can easily test the pneumatic brake systems of a tractor-trailer. The device is used by inputting into the device the electrical and pneumatic outputs of a tractor and by outputting electrical and pneumatic transmissions from the device into a trailer. The device accepts input from a tractor and produces output to a trailer for testing purposes. The testing device is compact and portable and affords a mechanic a convenient tool for efficiently carrying out the necessary safety tests on both the tractor and trailer which may be physically connected or disconnected at the time the testing occurs.

A method and apparatus for testing motor vehicle anti-skid braking systems is disclosed which is particularly well suited for production line verification of the anti-skid braking system integrity. The method comprises monitoring the operation of a pressure generating device which operates intermittently to generate brake actuating pressure independently of application of the vehicle brake pedal while simultaneously and cyclically applying a predetermined operating force to the vehicle brake pedal and measuring the distance of travel thereof for each successive operation. The first phase of the test procedure enables verification of the operation of the pressure generating device and associated controls therefor whereas the second phase of the test sequence verifies the absence of fluid or pressure leakage in another portion of the braking system. The apparatus comprises sensor means operative to sense operation of the pressure generating device while simultaneously controlling operation of a pressure actuated device operative to sequentially and cyclically depress the vehicle brake pedal and simultaneously measure the amount of travel associated with subsequent applications of force thereto.

Device and method for determining a wheel braking pressure and/or an admission pressure in a braking system in which pressure medium is introduced from a reservoir for the pressure medium having an admission pressure into a wheel brake through at least one shutoff device for inlet and/or outlet and/or passage of a pressure medium, it being possible to remove pressure medium from the wheel brake through at least one means delivering the pressure medium. In so doing, a pressure quantity representing the admission pressure is estimated, at least one operating state of at least one actuator in the braking system is detected and the wheel braking pressure is estimated as a function of the estimated admission pressure and the detected operating states.

For the detection of undissolved gas in the brake system; hydraulic pressure is built up and at least one characteristic value for the pressure buildup such as the master cylinder pressure, the brake pedal distance, the drop in storage chamber pressure, etc., is checked to see if it exceeds a predetermined limit value. If this limit value is exceeded, it is assumed that there is an unacceptable amount of undissolved gas in the hydraulic component of the brake system.