Bending elasticity in rotors (TM 620)

Bending elasticity in rotors (TM 620)

investigation of bending vibrations in rotors



  • Critical speed and resonance are phenomena that play essential roles in many machines and systems.
  • In particular, resonance states with impermissibly high vibration amplitudes can occur in rotating shafts and rotors at certain speeds, which in some cases can even lead to destruction of the machine.
  • To prevent this, the system is operated well above or below the critical speed and driven quickly through the critical speed range.
  • Therefore, knowledge of critical speeds and vibration modes is important in the design and operation of machines with bending elasticity in their rotors.
  • The TM 620experimental unit can be used to clearly demonstrate phenomena such as resonance, self-centring and vibration modes.
  • The model-like structure of the experimental rotor as a thin, elastic shaft with rigid mass disks allows simple theoretical comprehension of the vibration phenomena that occur.
  • The influence of different parameters can be studied thanks to the free choice of bearing and disk arrangement. The limitation of the amplitudes at a rapid resonant cycle can also be demonstrated.
  • A three-phase motor drives a rotor shaft, onto which one or two masses may be fixed at various distances.
  • The rotor shaft is mounted in two self-aligning ball bearings and connected to the motor via a flexible coupling.
  • The electronically controlled speed can be selected via two potentiometers and is continuously variable. It is displayed on a digital display.
  • The positions of and distances to elements fixed onto the rotor shaft can be read on a scale mounted in parallel with the rotor.
  • A transparent protective cover and safety bearings immediately next to the masses ensure safe operation.
  • The measured values can be displayed and analysed on a PC using the optional TM 620.20unit for data acquisition.

Technical Details:


  • investigation of bending vibrations and resonance in rotors
  • 2 self-aligning ball bearings to support the rotor shaft, positionable at any point
  • 2 masses to be secured at any point
  • safety bearing and transparent protective cover for safe operation
  • three-phase motor: 2 pre-selectable speed ranges; speed electronically controlled and continuously adjustable
  • digital speed display
  • system for data acquisition (TM 620.20) available as an option

Technical Data:

  • Three-phase motor
    • power: 0,25kW
    • speed: 3000min-1
  • Rotor shaft
    • L=500mm
    • Ø 6mm
    • high tensile steel
  • Mass 2x, disk-shaped
    • m=965g
    • Ø 80mm
    • hardened steel
  • Rotor bearing
    • 2x self-aligning ball bearings
    • 2x safety bearings
    • safety bearing play: ±3mm
    • adjustable bearing clearance: 300…470mm
  • Measuring ranges
  • speed: 300…3000min-1
  • scale for measuring distance: 0…500mm
  • 230V, 50Hz, 1 phase
  • 230V, 60Hz, 1 phase; 120V, 60Hz, 1 phase
  • UL/CSA optional

Dimensions & Weight:

  • L x W x H: 1150x390x375mm
  • Weight: approx. 49kg

Learning Objections/Experiments:

  • investigate bending vibrations and resonance of a rotating shaft
  • determine critical speeds with different arrangements of the bearing and masses on the rotor shaft and compare with theory
  • investigation of the rotor’s self-centering effect

Scope of Delivery:

  • 1 experimental unit
  • 1 set of instructional material


  • investigation of bending vibrations in rotors
  • determine critical speeds
  • positions of rotor bearing and rotating mass can be adjusted


  • Optional:
  • –      TM 620.20 System for data acquisition
  • –      WP 300.09 Laboratory trolley


Due to the continuous development of our products, the goods supplied may vary in detail to that illustrated on this Website.