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Related Standards

USA Patent 6,662,641, December 16, 2003

METHOD AND DEVICE TO MEASURE THE BRAKE FORCE FOR RAILROAD VEHICLES

AAR Approval

Calibration

Calibration Frame Combinations

Why this experimental development was undertaken

Development of a brake disc force measuring mechanism for high-speed trains:

• There is a need to extend the limits of the existing technology and apply it in a new environment and context to meet the objective.
• There is an insufficiency of technological knowledge to achieve the objective and it is required to conduct work for the purpose of advancing the understanding of technology.
• We attempted to resolve these problems through experiments and analysis and achieve technological advancements, generation and discovery of knowledge that advances the understanding of high-speed trains braking technology.

Current state of the technology

The existing technological knowledge is insufficient:

• Existing methods and measuring devices are not applicable
• Requirements and specifications for high-speed trains are completely different from the existing regular speed vehicles
• Too many variables and unknowns: higher impact, various caliper types, larger braking surfaces, different securing mechanisms for pads
• Parameters and conditions are outside the operating range studied so far
• Characteristics of the context is evolving
• Theory and prediction mathematical models do not exist. Data is not available. All the currently available braking systems require extensive and comprehensive lab and filed experiments.

Technology and Knowledge challenges

• Accurate generation of a linear correlation between the applied forces and sensor body deformation with minimal calibration points.
• Measurement technique for the actual high-speed brake disc forces with a linearity, accuracy, and repeatability of 99%.
• Elimination of the forces generated by the random and relative displacements, rotations and angularities resulted from the high-speed operating environment.
• Unique installation processes and techniques to ensure measurement accuracy and repeatability.
• Ensure that the same sensor could be used for all the four brake disc systems as provided in the application

Technology needs for High-Speed brake disc force measurement

• Find a mechanism that allows compensation of undesired forces and displacements, vs the traditional single load cell block.
• Use a bending effect sensor instead of a compression sensor, to address the clearance parameter limits.
• Minimize the influence of lateral and tangential forces while seeking equilibrium condition
• Obtain mechanism’ deformation linearity (sensor and components)
• Eliminate the consequences of lateral and tangential forces for the emergency brake measuring test
• Obtain a solution for safely operating the mechanism while also ensuring optimal position for measurements repeatability.

Advancements

Technological Advancements – Technology Know-How, Methodologies and Technics gained (1 of 3)

Technology Know-How: New Device Development

• Developed new sensors to accurately generate a linear correlation between the applied forces and sensor body deformation to measure the actual brake disc forces up to 12,000 lbs. with 99% accuracy regardless of the type of brake disc.
• Developed new sensors required minimal calibration points and eliminated the influence of forces generated by the random and relative displacements, rotations and angularities between disc and pad.

Knowledge of new constituents: New Sensor main Adaptor

• Developed a new sensor main adaptor concept, shape, and configuration with self-holding magnets to securely position the sensors without touching the caliper or the disc to securely be positioned to sit on the 2 caliper protuberances for all the 4 caliper models.

Technological Advancements – Technology Know-How, Methodologies and Technics gained (2 of 3)

New Technique to reduce the influence of the lateral forces and displacements

Eliminate forces generated by random and relative displacements, rotations and angularities between disc and sensor pad:

• Rubber transoms between sensor body connection with the adaptors to ensure a free sensor body movement and positioning.
• Developed a new geometry for the central aria of the main adaptor in order to minimize the influence of lateral forces
• Developed a new way for positioning the magnet holders in order to eliminate the potential lateral contacts to disc or caliper

Knowledge of how constituents: New Sensor Extra Cover system

• New sensor extra cover to: (i) Resist to triple the actual rod tangential forces and also to protect the side bars for triple the lateral forces (ii) Use special spring steel material at 55Rc.

Technological Advancements – Technology Know-How, Methodologies and Technics gained (3 of 3)

Knowledge of how new constituents are embodied in the materials and work together: New Covers Materials & Techniques

Developed new sensor’ extra covers to triple the actual rod and side bars resistance against tangential and lateral forces to ensure:

• The self-positioning sensor is always in the correct measurement position regardless of the transversal or longitudinal angularity.
• The developed sensors could handle lateral and ( tangential) forces up to 2,000 lbs.
• The developed sensor can handle radial forces up to 12,000lb with 99% linearity, repeatability and accuracy.
• The new covers enable the manufacturer to open the sensor for eventual repairs without destroying all the already assembled sensor covers.

Lessons learned

New Technique: good sensor linearity / repeatability

Obtain a good sensor linearity/repeatability while the sensor body and the main adaptor are both working in bending effect, while testing the assembly on all the four calipers when we use:

• Self-holding magnets while making sure that the magnets do not touch the caliper in any way to disturb the measurement.
• Developed specific sensor’s adaptors facing both the caliper and the disc sides.
• Rubber transoms connections between both the sensor body and the adaptors to ensure a free sensor body movement and positioning and to reduce lateral parasite forces and displacements.

Conclusions

We consider that our systematic investigation in the area of the sensors measuring the brake forces for the High-Speed Trains represents a huge step forward for railway brake technology knowledge.

So far, the new sensor is undergoing further experimental tests.

• So far, the new sensor is undergoing further experimental tests.

First device to measure the brake disc force for High-Speed Trains.

Our experimental process led to the generation of new technological knowledge and know-how.

• This includes the knowledge of how various constituents of the sensor assembly are embodied within the devices, materials, processes, and work together to meet the objective.