MICHAEL SCOTT SMITH, P.A.
Physician Assistant at Williams St, Owosso, MI

5046786, Sep 10, 1991

Jun 12, 1990

7/537083

Jeffery S. Johnston - Haslett MI
Michael G. Smith - Owosso MI
Mark Karpinski - Rochester Hills MI

Midland Brake, Inc. - Kansas City MO

B60T 1300

303 7

A pressurized fluid control module is provided for a tractor-trailer brake system to effect the appropriate braking function. The pressurized fluid control module is combined with pressure inlet fittings for the introduction of a pressurized fluid, a plurality of interconnected pressure chambers for selectively actuating the vehicle service and parking brake circuits, a proportioning circuit to vary the fluid pressure to the rear service brakes depending on the presence or absence of the trailer, a protection circuit to prevent the loss of pressurized fluid within the pneumatic brake actuation and release circuit upon detachment of the trailer from the tractor, quick release valves to release residual fluid pressure in the pressurized fluid control module and the trailer service brake circuit upon the cessation of braking effort, module check valves to prevent fluid pressure losses between the chambers, a vehicle rear stop lamp switch sensitive to the fluid pressure in one of the pressure chambers, and a plurality of outlet fittings to the aforementioned service and parking brake circuits. The pressurized fluid control module of the present invention, as a single, integrated, multifunctional unit, obtains control over the tractor rear service brake circuit and parking brake circuit and the trailer service and parking brake circuit depending on the presence of the trailer, the braking effort exerted by the vehicle operator via the foot-actuated treadle assembly service brake valve assembly, the position of the hand-actuated trailer service brake valve, and the position of the manifold push/pull valve.