SBIR-STTR Award

The bonded resistance strain gage has made possible a variety of force sensing transducers, commonly known as "load cells." Widely used types of load cells include the column, the bending beam, the ring, the circular plate and the shear web. To instrument the anchor pins used in heavy truck air braking systems, STRAINSERT will utilize proven research and evaluation techniques implemented during the development of STRAINSERT's Load Sensing Shear pins. These Load Sensing Shear pins, or in short, the Clevis Pin or Load Pin, are designed as a direct replacement for the non-instrumented existing pins. This provides for a low cost method of force measurement without impacting or reducing the load capacity of the existing brake system design. STRAINSERT's patented method of internally bonded and sealed strain gage circuits inside small holes drilled into the Load Pin, provide for a robust transducer capable of surviving the harshest environments. Internally gaged load pins, invented by STRAINSERT (US Patent 3,695,096), have been repetitively proven to be consistently accurate to within 0.5% of the full load capacity. STRAINSERT will research feasibility by assessing strength, interoperability, maintenance, and integration issues of incorporating an instrumented anchor pin into a heavy truck brake.Commercial Applications:Phase_I will result in a low cost instrumented anchor pint prototype design for monitoring the braking torque produced by heavy trucks using air braking systems. This prototype design will be a direct replacement to an existing brake system anchor pin and provide an instantaneous signal to an electronically-controlled pressure regulator or early warning alarm. Pins of this type can also be used to detect over loads of truck lifts, cranes and hoists. Other applications include accurately monitoring distribution of force among lifting and tie down cables used in the trucking, railroad and shipping industries.

Using experimental models developed in Phase I, tests were performed and established that a clear correlation exists between the force sensing anchor pins and the actual torque produced at the brake. In addition, results of Phase I work suggest that internally gauged instrumented anchor pins are a suitable replacement for most of the current anchor pin installations used in heavy truck brake applications. A total of five experimental models were developed based on Vehicle Research Test Center VRTC) test data and engineering analyses performed during Phase I. These models were designed as replacements for leading as well as trailing anchor pins.The fundamental technical objective of Phase II will be to assess the performance and capabilities of prototype instrumented anchor pins during Phase II development and testing. Ultimately, instrumented anchor pins are to be integrated into fleet test vehicles and collect over-the-road test data. Testing will be conducted on a heavy truck test vehicle in accordance with test plans established in Phase II. Testing will address, as a minimum, the following technical issues:oTorque vs. anchor pin force relationships between axlesoEvaluate brake failure conditions based on anchor pin output signoEvaluate brake wear scenarios from anchor pin output signaturesoAssess anchor pin performance in environmental conditions

Anticipated Results/Potential Commercial Applications of Research:
:Instrumented anchor pins developed through Phase II research efforts can be used to indicate force, regulate brake pressure, provide early warning of degraded performance or input to another control system. Successful development and integration of instrumented anchor pins into a comprehensive air brake systems will provide trucks the ability of equalized braking, wheel speed adjustment, and brake system overall status.

Keywords:
testbed demonstrators, early warning systems, fleet testing, brake wear detector, brake failure detector, equalized braking, instrumented anchor pin, force detection.