Strain Gage Measurements in Diesel Engine Bolts

To measure bending and axial loads in diesel engine or heavy duty truck components, encapsulated general purpose strain gages were applied in half bridge patterns, 120 degrees apart on the bolt shank, at elevated temperatures up to 350 degrees C. Bolts can also be instrumented with strain gages to verify torque specifications by measure clamping force.

Window Force Measurement

Power actuated windows, doors, lift gates and sunroofs on today’s vehicles have created the potential for being trapped or pinched as these mechanisms open and close. We have developed sensors to allow the evaluation of the obstruction detection mechanisms used in these vehicles, accurately determine the force levels applied, and most of all to help prevent these injuries from occurring in the first place. The sensor was designed to mount on the vehicle window glass and monitor the ‘auto-up’ feature. This hands free package features selectable spring rates and obstacle distances, allowing one sensor to measure multiple applications.

Strain Gage Measurements on Rotating Shafts

A perfect example of transducerizing your component without adding a separate torque sensor is by bonding strain gages directly to a rotating shaft. This allows direct measurements which is sensitive to torque loading. For these measurements, calibration is provided by loading the shaft statically and calculating the results. Our partner Sensor Developments, Inc. provides a full line of customizable reaction torque sensors, rotating torque sensors and companion readout instruments for additional torque measurement needs.

Custom Seat Belt Force Measurement

By replacing an off-the-shelf seat belt force transducer with strain gages instrumented to the anchor of a seat belt, HITEC is able to “transducerize” the seat belt mechanism to measure tensile force during testing.

EGR Cooler Instrumentation for Validating Surface Temperature Distribution and Stress Detection

Exhaust gas recirculation coolers are a heat exchanger component installed in the EGR circuit of a diesel powered engine. The cooler circulates exhaust back to the engine in order to reduce NOX emissions. Strain gages are used to validate temperature distribution and detect any stress that may cause failure during testing. These results are typically compared with CFD simulation as well as temperature measurements from an infrared camera and finite element models.

Exhaust System Strain Gage for Durability Testing, Destructive Testing and Stress Evaluation

HITEC’s application expertise lies with conventional strain gage installation methods as well as strain sensor measurements on extremely hot surfaces, such as exhaust systems. Weldable or free-filament strain gages applied using ceramic cement or Rokide™ Flame Spray are used for temperature durability testing, destructive testing and stress evaluation.

Load Sensors on Trailer Axle Hubs

Semi-conductor strain gages were utilized for validating and verifying the process that determines axle bearing preload. The component was instrumented with semi-conductor strain gages in a full bridge configuration due to low strain levels.

Spare Tire Lift Force Sensor

Many of today’s SUVs utilize a cable to support the spare tire under the vehicle. This cable holds the tire securely against the vehicle frame. If this cable loosens, there can be a considerable amount of cyclical force developed in the cable due to the inertia of the tire. This cyclical force can both weaken the cable or its mounts, and can become a severe problem if the vehicle is involved in a crash, where the loose cable might snap, allowing the tire to become a projectile. We have developed a force sensor which mounts between the lift cable and the rim of the spare tire. The sensor can monitor the cable tension during lifting and seating operations, as well as under driving conditions to determine if the mechanism ‘settles’ during use.