arrow_back_ios

Main Menu

See All Software See All Instruments See All Transducers See All Vibration Testing Equipment See All Electroacoustics See All Acoustic End-of-Line Test Systems See All Academy See All Resource Center See All Applications See All Industries See All Services See All Support See All Our Business See All Our History See All Global Presence
arrow_back_ios

Main Menu

See All Analysis & Simulation Software See All DAQ Software See All Drivers & API See All Utility See All Vibration Control See All High Precision and Calibration Systems See All DAQ Systems See All S&V Handheld Devices See All Industrial Electronics See All Power Analyzer See All S&V Signal Conditioner See All Acoustic Transducers See All Current and Voltage Sensors See All Displacement Sensors See All Force Sensors See All Load Cells See All Multi Component Sensors See All Pressure Sensors See All Strain Sensors See All Strain Gauges See All Temperature Sensors See All Tilt Sensors See All Torque Sensors See All Vibration Transducers See All Accessories for Vibration Testing Equipment See All Vibration Controllers See All Measurement Exciters See All Modal Exciters See All Power Amplifiers See All LDS Shaker Systems See All Test Solutions See All Actuators See All Combustion Engines See All Durability See All eDrive See All Production Testing Sensors See All Transmission & Gearboxes See All Turbo Charger See All Training Courses See All Upcoming Webinars See All Acoustics See All Asset & Process Monitoring See All Durability & Fatigue See All Electric Power Testing See All NVH See All OEM Custom Sensors See All Reliability See All Structural Dynamics See All Weighing See All Automotive & Ground Transportation See All Calibration See All Installation, Maintenance & Repair See All Support Brüel & Kjær See All Release Notes See All Compliance
arrow_back_ios

Main Menu

See All nCode - Durability and Fatigue Analysis See All ReliaSoft - Reliability Analysis and Management See All API See All Experimental Testing See All Electroacoustics See All Noise Source Identification See All Environmental Noise See All Sound Power and Sound Pressure See All Noise Certification See All Industrial Process Control See All Machine Analysis and Diagnostics See All Structural Health Monitoring See All Electrical Devices Testing See All Electrical Systems Testing See All Grid Testing See All High-Voltage Testing See All Dynamic Weighing See All Vehicle Electrification See All Calibration Services for Transducers See All Calibration Services for Handheld Instruments See All Calibration Services for Instruments & DAQ See All On-Site Calibration See All Resources See All Software License Management See All Business Ethics

Which fit is the right one?

An explanation of the significance of ISO fits to standard shafts and holes

Correct torque application to the transducer is crucial for measuring torque. It is the only way to obtain precise and reliable measurement results. Torque is applied mainly via flanges using a friction joint, a method that has proven its worth a thousand times over with torque flanges, for example T12. Here a choice has to be made between ease of mounting through loose running fits or small unbalance through minimal clearance. In many cases, no flange is available at the customer side, but instead a shaft stub. In this case, choosing the right fit is extremely important. It is the only way to ensure correct torque introduction with dynamic processes, too.

Couplings

It is essential to eliminate parasitic loads on all transducers to ensure correct mounting of torque transducers [1]. HBM provides bellows couplings for torque transducers using shaft stubs (Fig. 1) and multiple-disk couplings for the torque flanges. The coupling supplier offers additional mounting accessories for these multiple-disk couplings, e.g. clamping hubs.

The bellows couplings offered by HBM feature H7 tolerance holes. HBM recommends to implement a tolerance of j6 for the shaft diameter, to produce the preferred fit of H7/j6 [2]. [4] suggests additional securing against rotation for this configuration (Fig. 3). For this reason, the couplings come with additional clamping bolts. Irrespective of whether bellows couplings offered by HBM, centering seats of flanges or clamping hubs are used, the decisive factor is that: Choosing the right fit is crucial to successful measurement.

Choice of fits

DIN 7151 [3] or ISO 286 provide basic information for selecting the right fit. Figure 2 gives a first overview.

Choosing the right fit depends on the mounting and dismounting options at the user's site. In general, the user can choose freely to ensure correct torque application in all conditions of use. However, the user has sole responsibility for obtaining correct measurement results. Application examples and types of fits are specified in [4]. Fig. 3 shows an excerpt.

Conclusions

There are various possibilities for connecting shafts with holes. Be it interference and transitions fits, clearance fits, clamping connections or feather keys - the right manufacturing tolerance is crucial to the quality of measurement. HBM offers extensive support. Our tip: Do not refer to the data sheet only in the design, use the mounting instructions, too. Documentation for all torque products can be downloaded from HBM's web site at any time. In addition, the technical articles about frequently asked questions, available on the Internet, are very useful.

References

[1] Rainer Schicker, Georg Wegener: Measuring Torque Correctly, ISBN 3-00-008945-4, Published by Hottinger Baldwin Messtechnik GmbH, Darmstadt

[2] HBM Mounting instructions T20WN A0726_13.1_en/de/fr, Published by Hottinger Baldwin Messtechnik GmbH, Darmstadt, 2011

[3] DIN 7157, Passungsauswahl, Toleranzfelder, Abmaße, Paßtoleranzen, German standards are exclusively sold by Beuth-Vertrieb GmbH, Berlin 30 and Köln

[4] Böge, A.: Das Techniker-Handbuch, 2. Auflage, Friedrich Vieweg & Sohn GmbH, Braunschweig, 1969