Proud Distributors of GUNT Hamburg, UTEST, FOUR E’s Scientific & LABTECH ITALY

Free and forced vibrations (TM 155)

demonstration of basic fundamentals of mechanical vibration theory

Code TM155


  • Forced vibrations occur in a variety of ways in engineering.
  • While they are desirable in vibrating screens or vibrating conveyors, they are often unwanted in engines or other rotating machines.
  • The TM 155experimental unit clearly demonstrates the fundamentals needed to deal with free and forced vibrations.
  • The differences between the two main types of excitations for forced vibrations can be shown on a simple vibration model.
  • The central element of the experimental unit is a sturdy aluminium profile frame to which the different experimental setups are attached.
  • A bar-type oscillator is used as the vibration system. This offers easy and flexible configuration.
  • The spring, damper and vibration exciter can be mounted in any position.
  • An imbalance exciter and a displacement exciter are available for spring base-point excitation.
  • The excitation frequency is set and displayed on a control unit.
  • An oil hydraulic damper allows damped vibrations with adjustable damping level.
  • A mechanical drum recorder offers the option of recording the vibrations.
  • The measured values can be displayed and analysed on a PC using the optional TM 155.20unit for data acquisition.
  • A demonstration unit for torsional vibrations (TM 150.02) is available as an accessory.

Technical Details:


  • fundamentals of mechanical vibration theory; free, damped and forced vibrations
  • bar-type oscillator
  • 3 coil springs
  • imbalance exciter with DC motor
  • displacement exciter with DC motor
  • electronic control unit with digital display, adjustable excitation frequency
  • damper with oil fill
  • electrically driven drum recorder
  • amplitude meter with electrical contact for triggering devices
  • storage system for parts

Technical Data:

  • Bar-type oscillator: L x W x H: 700x25x12mm, 1,6kg
  • Coil springs:
    • 0,75N/mm
    • 1,5N/mm
    • 3,0N/mm
  • Exciter frequency: 0…50Hz, electronically controlled
  • Imbalance of the imbalance exciter: 0…1000mmg Stroke of the displacement exciter: 20mm
  • Damper constant: 5…15Ns/m, oil-filled
  • Mechanical drum recorder:
    • feed: 20mm/s
    • paper width: 100mm
  • 230V, 50Hz, 1 phase
  • 230V, 60Hz, 1 phase; 120V, 60Hz, 1 phase
  • UL/CSA optional

Dimensions & Weight:

  • L x W x H: 1000x420x900mm
  • Frame opening W x H: 870x650mm
  • Weight: approx. 52kg
  • Storage system:
  • L x W x H: 1170x480x237mm
  • Weight: approx. 12kg

Learning Objections/Experiments:

  • free vibrations
  • damped vibrations
  • inertia force and displacement excitation
  • forced vibrations
  • resonance
  • amplitude response and phase response

Scope of Delivery:

  • 1 experimental unit
  • 1 bar-type oscillator
  • 3 coil springs
  • 1 imbalance exciter
  • 1 displacement exciter
  • 1 control unit for imbalance exciter
  • 1 damper
  • 1 amplitude meter
  • 1 drum recorder
  • 1 storage system with foam inlay
  • 1 set of instructional material


  • demonstration of basic fundamentals of mechanical vibration theory
  • damping and resonance in forced vibrations
  • two different principles of vibrational excitation


  • Optional:

–      TM 155.20 System for data acquisition

–      TM 150.02 Free and damped torsional vibrations


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