August 2015

August 2015
Normally the TorqueTrak instruments are used to measure and transmit true mechanical torque data on a rotating shaft, but the instruments are not limited to this application. You can transmit data for any property that can be sensed with a full-bridge sensor (or a "simulated" full bridge.) This includes Strain - Torque, Bending, Tension and Compression - even Pressure, Temperature and Acceleration.

Shown below is a great application story from our customer Engineering Dynamics Incorporated (EDI) about measuring axial load - thrust/compression - on a pump shaft.
If you have a good application or success story involving the TorqueTrak instruments that you would like to share in this newsletter, please send it to me for consideration.
Thank you,

Bob Holden
International Sales

Axial Thrust Measurement in Vertical Turbine Pump
By Troy Feese and James Clark
Engineering Dynamics Incorporated - San Antonio, Texas

Engineering Dynamics Incorporated (EDI) was requested to help perform an axial load test on a vertical water pump. Since commissioning, the pump experienced accelerated bearing and shaft wear. There was concern that problems might be due to up-thrust resulting in a bow in the vertical shaft. The pump is driven by a 250 HP induction motor with variable frequency drive (VFD) speed control. The thrust bearing is located at the top of the motor.
The TorqueTrak 10K telemetry instrument from Binsfeld Engineering and single-axis strain gages were installed on the shaft as shown in Figure 1. Calibration was done using hydraulic cylinders and a lifting plate under the coupling hub. The scale factor was experimentally determined based on the slope of the linear fit as shown in Figure 2.

EDI's data acquisition system was used to record all test data. The pump was started and brought to 100% speed. As shown in Figure 3, the axial force started at 1700 lbs (hanging weight of pump) and then increased to 6600 lbs. A positive reading indicates downward axial force. Therefore, no up-thrust condition was observed during startup.

The pump was then tested from 70% to 100% operating speed. The measured force includes the thrust as well as the hanging weight of the line shafts and pump impellers. All values were positive and remained in the 6000 to 7000 lbs range as shown in the table below:
Axial Force
713 RPM
6900 lbs
648 RPM
6540 lbs
577 RPM
6200 lbs
506 RPM
6080 lbs
A final test was conducted with other pumps running at the station. The discharge valve was partially closed to increase discharge pressure and simulate rated head. The maximum axial force measured at this operating condition was 7600 lbs and compared well to the predicted down-thrust of 7500 lbs shown on the drawing.

Using the Binsfeld TT10K, up-thrust was ruled out as a possible cause of the bearing and shaft issues. Damage may have instead been caused by sediment in the river water being pumped by the station.
Figure 1
Figure 2
Figure 3
Introducing the NEW TorqueTrak TPM2
Binsfeld Engineering is pleased to introduce the new TorqueTrak TPM2 torque and power monitoring system for rotating shafts. The all-digital system features a RS422 full-duplex interface with system setup and configuration via computer software (provided).
Like all Binsfeld Engineering torque telemetry systems, the TorqueTrak TPM2 does not require shaft modification or machine disassembly. Rugged and precise, the TorqueTrak TPM2 is available for shaft diameters from 0.75"(19mm) to 40 inches (1016mm) and is ideal for almost any torque and power evaluation project.

Click here for the TorqueTrak TPM2 Product Data Sheet.