CIVIL ENGINEERING TORQUE MEASUREMENT APPLICATIONS
CIVIL ENGINEERING TORQUE AND POWER APPLICATIONS
TORQUE MEASUREMENT& POWER MONITORING CASE STUDIES
See how customers around the world are using TorqueTrak systems from Binsfeld Engineering to troubleshoot and optimize their machinery, control processes, increase efficiency, prevent damage and solve challenging problems — in short, saving time and money by making smart data-based decisions.
Torque Data Reveal Gearbox Weakness
|A large urban city water treatment facility uses large power driven chain-linked scrapers called “flights” to extract impurities (i.e. mud and silt) from each cistern as part of the water purification process. The drive system, specifically the gear sets, would repeatedly fail. Excessive torque was the suspected cause.
Engineers used several TorqueTrak 10K telemetry instruments from Binsfeld Engineering at various sections of the system to measure the true operating torque. It was determined that operating torque was normal, but the gear sets were undersized relative the actual workload. Stronger gear sets were installed and the failures have ceased. Precise torque measurement data led the engineers toward the correct solution to the an expensive gearbox failure problem.
Column Pump Torque Measurement
|A civil engineering company in Chicago was hired to determine the start-up torque for a column pump at a water treatment plant for the City. The City desired to upgrade the pump drive system by employing reduced voltage starters to minimize in-rush current.
Some of the oldest pumps in the system required extra power during start-up, nearly twice the operating horsepower, depending on the open or closed state of the discharge valve. This problem could be resolved by over-sizing the motor (a costly option) or by optimizing the timing of the discharge valve opening, relative to the torque load. Both options pointed to one question: How much torque is required for starting the pump?
Engineers used Binsfeld telemetry to transmit live torque signals from Micro-Measurements strain gages on the impeller drive shaft while simultaneously monitoring RPM with a tachometer during trial start-ups. The torque and RPM data provided the information engineers needed to make informed decisions on how to best optimize the pump performance. In a matter of hours, real impeller torque measurements pointed to a conclusive solution that would otherwise be only guessed at based on time consuming and complicated modeling.
Vertical Lift Bridge
Houghton Lift Bridge, Houghton, MI – Mechanical rework and painting of the double deck, vertical lift bridge at Houghton, MI had potentially changed the weight of the movable span. Lunda Construction, the primary contractor, was required by the Michigan D.O.T. to check the balance between the span and counterweights for proper and safe operation. At each corner of the bridge a large cable connects the span to the counterweight over a motor driven sheave. How could Lunda check the overall balance of this counterweighted cable system?
Binsfeld Engineering was contracted to measure the torque simultaneously on the four drive shafts to determine if an imbalanced condition existed at any of the four corners. With Micro-Measurementstorque sensitive strain gages and telemetry transmitters attached to each drive shaft, torque data was recorded concurrently as the span was raised and lowered. By comparing the lifting torque to the lowering torque, and correcting for friction, it was verified that the movable span was slightly heavier than the combined counterweights (a desired condition) and that all four corners were within acceptable balance with each other.
Double-leaf bascule draw bridge
|The Park Street Bridge in Alameda County, California is a four-lane double-leaf bascule (draw) bridge spanning 372 feet across the Oakland Tidal Canal between the Cities of Alameda and Oakland.
When rework construction modified the weight of the original lift spans the Alameda County Engineers needed to determine the proper counterweights to prevent the lift drive motors from overloading. By measuring torque on the main pinion shafts used to lift the bridge, it was easy to determine and optimize the drive loads through adjustment of the counterweights on each span. Torque sensitive Micro-Measurements strain gages were bonded to the pinion drive shafts and two TorqueTrak telemetry systems were used to communicate the strain gage signals from both pinions simultaneously as the shafts rotated.
The County has a number of movable bridges that occasionally require adjustment due to repaving or other mechanical changes. With the Binsfeld telemetry equipment, torque and balance measurements can be made quickly and accurately, eliminating guesswork and potential drive overload problems.
Axial Thrust Measurement in Vertical Turbine Pump
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:
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.
BINSFELD ENGINEERING INC.
Binsfeld's Torque Measurement Systems measure true mechanical torque and power on rotating shafts. We also offer consultation, strain gaging and installation services.
Binsfeld's Rotary Temperature Transmitter Systems provide accurate and reliable temperature control on heated godets and calendars. We also offer design and OEM services.
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