Appeal No. 2005-0993 Page 6
Application No. 10/056,156
skid condition by any of the several techniques known in the art, and generates
an electrical signal communicated to a control valve, illustrated as a solenoid
valve 42 associated with the wheel in or in danger of skidding. The valve 40
controls the flow of a pressurized fluid, which may be either a gas or a liquid
through a passageway 44 formed through the brake shoe 34 and brake pad 40 to
the interface 50 between the brake pad 40 and the brake drum 36. The pressurized
fluid is derived from pressurized fluid source which may be static pressurized fluid
supply, or may comprise a compressor 46 and accumulator 48 as illustrated in Figure 2.
The pressure of the fluid in the pressurized source must exceed the maximum pressure
that can be applied to the brake shoe by the pressurized braking system by a
predeterminable pressure dependent upon the mechanical configuration of the brake
system.
Actuation of Blatter's valve 42 in response to a signal from the control logic 14
injects the pressurized fluid between the drum and the pad. The fluid circulates across
the entire face of the pad due to wear grooves and the rotation of the drum 36. This
circulation combined with the dynamic wedge effect commonly observed in journal
bearings will cause the pad to rise slightly against the force generated by the piston in
brake cylinder 32 reducing the contact area between these two elements. The pads will
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Last modified: November 3, 2007