Belt drive and belt friction (TM 220)

Belt drive and belt friction (TM 220)

friction of different belt types on a metal pulley



  • The belt drives are machine elements that are classed as traction mechanisms in the field of transmission or conversion elements.
  • They transfer torque and speed between guiding members such as wheels or pulleys.
  • The motion is transferred by traction mechanisms that can only absorb tensile forces.
  • Toothed belts and chains deliver positive transmission of movements.
  • Traction mechanisms such as cables, flat belts and V-belts, on the contrary, allow for non-positive transmission.
  • In non-positive belt drives, the circumferential force between the belt and the pulley is transmitted according to the principle of cable friction.
  • Cable friction arises due to tangential static-friction forces at the points where the cable is in contact with the wheel or the pulley.
  • Eytelwein’s cable friction formula is used to calculate both cable and belt friction.
  • The TM 220experimental unit allows the study by experiment of belt drives and belt friction.
  • At the core of the experimental unit is a cast iron pulley, whose circumference features grooves for V-belts and flat belts.
  • The pulley is mounted on ball bearings and is powered by a crank handle.
  • Its flywheel mass favours an even rotation of the pulley.
  • The belts rub on the pulley at a wrap angle between 30° and 180°.
  • The wrap angle can be adjusted in increments of 15°.
  • Two spring balances detect the tensile forces on the respective belt ends.
  • This makes it possible to precisely adjust the belt tension using a threaded spindle.
  • Two flat belts made of different materials, a V-belt and a cable belong to the scope of delivery.
  • The experiments compare different belt types and materials and investigate the effect of the wrap angle.
  • In addition, for V-belts, it is possible to study how the groove shape affects the coefficient of friction.

Technical Details:


  1. function of a belt drive
  2. belt friction and comparison of different belt materials and types
  3. ball-bearing mounted pulley with 3 different belt grooves
  4. 2 flat belts made of different materials, 1 V-belt and 1 cable
  5. wrap angle of the belts 30°…180°, graduation 15°
  6. force measurement with 2 spring balances

Technical Data:

Flat belts:

  • 1x leather/polyamide, 15×2,2mm, Extremultus LT10
  • 1x polyamide, 15×0,6mm, Extremultus TT2


  • ISO 4184
  • profile: SPZ
  • 9,7×8,0mm, rubber/fabric


  • hemp, Ø=3mm


  • Ø=300mm
  • material: grey iron
  • Dynamometer: 100N ±1N

Dimensions & Weight:

  • L x W x H: 700x350x1100mm
  • Weight: approx. 47kg

Learning Objectives/Experiments:

  • effect of wrap angle, coefficient of friction and cable force (Eytelwein’s belt friction formula).
  • comparison of flat belts and V-belts.
  • consequences of an unadopted V-belt groove.

Scope of Delivery:

  • 1 experimental unit
  • 2 flat belts
  • 1 cable
  • 1 V-belt
  • 2 dynamometers
  • 1 set of instructional material


  • function of a belt drive


·         Optional: 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.