Forces in reciprocating engines (TM 180)

Forces in reciprocating engines (TM 180)

investigation of free mass forces and moments of a reciprocating engine



  • Every reciprocating engine generates mass forces.
  • The mass forces of the oscillating masses cannot be compensated completely, while the mass forces of the rotating masses are fully compensated.
  • By using several cylinders, it is possible that the forces compensate each other. However, disturbing moments may still occur.
  • The experimental unit TM 180enables investigation of the free masses and moments of a reciprocating engine with a single cylinder, with two cylinders or with four cylinders.
  • The engine model comprises pistons with plastic slide bushes.
  • The slide bushes do not require lubrication.
  • For each cylinder, the angle between cranks can be adjusted continuously.
  • As an aid, marks are provided at 0°, 90°, 180° and 270°.
  • The oscillating masses can be varied by using additional weights at the pistons.
  • The four-throw crankshaft is driven by a DC motor and a synchronous belt.
  • The speed is electronically controlled and digitally displayed.
  • The free forces and moments are recorded by force sensors placed at the support of the model.
  • All electronic functions are integrated in the display and control unit.
  • The display and control unit also contains the USBinterface for data acquisition.
  • The GUNTsoftware enables the detailed evaluation of the signals of forces and moments.

Technical Details:


  • experimental unit to investigate oscillating and rotating mass forces and moments of a reciprocating engine with up to 4 cylinders
  • simulation of single, 2- or 4-cylinder engines
  • electronically commutated and speed-controlled drive motor with digital speed display
  • continuous adjustment of the angle between cranks
  • force sensors to measure forces and moments
  • vibration isolation using rubber elements and suitable tuning
  • GUNT software for data acquisition via USB under Windows 8.1, 10

Technical Data:

  • Engine:
    • number of cylinders: 4
    • piston mass: 40g
    • additional mass: 41g
  • Crank drive:
    • mass of connecting rod: 18g
    • centre distance of cylinders: 35mm
    • crank radius: 15mm
    • length of connecting rod: 70mm
  • Measuring ranges
  • speed: 100…3000min-1
  • force: 0…500N
  • 230V, 50Hz, 1 phase
  • 230V, 60Hz, 1 phase; 120V, 60Hz, 1 phase
  • UL/CSA optional

Dimensions & Weight:

  • L x W x H: 420x370x350mm
  • Weight: approx. 40kg
  • L x W x H: 230x230x80mm (display and control unit)
  • Weight: approx. 1kg

Required for Operation:

  • PC with Windows

Learning Objectives/Experiments:

  • effect of mass forces:
    • mass forces in dependence on the speed
    • mass forces in dependence on the piston mass
    • first and second order mass forces
    • comparison of different crank drives:
    • 4-cylinder, symmetrical, 180° angle between cranks
    • 4-cylinder, non-symmetrical, 90° angle between cranks
    • 2-cylinder, 180° angle between cranks
    • single cylinder

Scope of Delivery:

  • 1 engine model
  • 1 display and control unit
  • 1 set of accessories (tools, additional masses)
  • 1 GUNTsoftware + USB cable
  • 1 set of instructional material


  • investigation of free mass forces and moments of a reciprocating engine
  • continuous adjustment of the angle between cranks
  • simulation of single, two- or four-cylinder engines



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