Belt Tension Meter RTM-400

Measuring range max. 10 - 800 Hz

Trummeter for measuring belt tension and for control the strand force of V-belts, tooth belts, power belts or similar. The optimal life time of a belt is depending on the correct belt tension. The set point for belt tension is specified as natural frequency in Hz or strand force in N.
Non-contact measuring occurs by infrared light - frequency measurement

Special Features

  • Measuring principle: Frequency measurement by LED light, if the belt is stationary 
  • The readings can be displayed as frequency (Hz) or strand force (N or lbf)
  • The belt tension meter RTM includes a display unit as well as 2 measuring probes:
    - plug in probe for one-hand operation
    - measuring probe with cable for limited access space
  • For determinating the spring force in Newton, 2 parameters are needed. Thereby the following restrictions are obtained:
    - free strand length 9.99 m
    - belt mass up to 9.999 kg/m
  • Measuring range 10 - 800 Hz
  • Multilingual operator guidance and display (german, english, french, italian, spanisch, portugese, swedish, norwegian, danish, finnish)
  • Manufacturer`s calibration report is included

Standard Features

  • Easy and save operation
  • Trummeter with rugged, handy plastic housing
  • Microprocessor controlled belt tension meter
  • Measurement with highest precision

Photo Gallery

Model RTM-400 inclusive 2 sensors

2 line LCD Display Sensor with cable (length approx. 1.2 m) for <br />applications with limited access space Plug-in Sensor for one-hand operation

Available Models

ModelMeasuring Range
RTM-400max. 10 - 800 Hz


operation drawing and picture belt tension meter RTM-400
The belt tension can be measured only when the drive is stationary. Preferably, the belt tension should always be measured at the center of the longer belt strand between the two drive pulleys. The distance to the belt can be 3 - 20 mm. Depending upon ambient light and surface of belt, the measurement can occur from a distance of max. 60 mm, whereas darker light and better reflection (can be obtained by attaching a reflective tape) admit a larger measuring distance.
The belt is tapped in order to make it natural oscillating. This static natural frequency is then measured by the probe with the aid of pulsed light. Care must be taken to ensure the light is sufficiently reflected by the belt. A reflective tape must be fixed if necessary.
formular for calculating the strand force
Measurement deviations of up to 10 % for several measurements taken on the same drive belt are as a rule not caused by a measurement error or fault in the unit. In most cases, measurement deviations are due to the mechanical tolerances of the drive systems.

Attention! Newton- or poundforce-calculations have a square factor higher error result!
formular for calculating the set point for belt tension

Belt Masses

Ribbed V-beltsPJ = 0.082
PM = 1.100
PL = 0.320
kg/m per 10 ribs
V-beltsSPZ = 0.074
SPB = 0.195

10 = 0.064
17 = 0.196
22 = 0.324
32 = 0.668
SPA = 0.123
SPC = 0.377

13 = 0.109
20 = 0.266
25 = 0.420
40 = 0.958

kg/m per belt

kg/m per belt
Power beltsSPZ = 0.120
SPB = 0.261

3V/9J = 0.120
8V/25J = 0.693
SPA = 0.166
SPC 0 0.555

5 V/15J = 0.252

kg/m per rib

kg/m per rip
Tothed belts
T 2.5 = 0.015
T 10 = 0.045

AT 3 0 0.023
AT 10 = 0.063
T 5 = 0.024
T 20 = 0.084

AT 5 = 0.034
AT 20 = 0.106

kg/m per 10 mm width

kg/m per 10 mm width
To measure the belt mass precisely, we recommend that you weigh the drive belt and then recalculate this weight based on a belt length of 1 meter.

The  table above contains comparison values for some belts.

Delivery Includes

scope of delivery belt tension meter RTM-400: Trummeter with carrying case, 2 measuring probes, 1 battery,
manufacturer`s calibration report and operating instruction in
german and english


Measuring range:10 - 800 Hz
Digital sampling error:< 1 %
Indicator error:1 Hz
Total error:< 5 %
measuring units:
Hz (Frequency) or
N, lbf (Strand force)
Measuring distance:3 - 20 mm
Display:2 line LCD, 16 characters per line
Languages:10 languages (german, english, french, italian, spanish,
portugese, swedish, norwegian, danish, finnish)
Input ranges:Free strand length: up to 9.99 m
Belt mass: up to 9.999 kg/m
Temperature ranges:Operation: +10 C ... 50 C, Transport: -5 C ... +50 C
Air humidity:85 % RH, max.
Power supply:9 V - Battery
Housing:Plastic (ABS)
Dimensions:126 x 80 x 37 (LxWxH)
Weight net (gross):Approx. 170 g (approx. 660 g)

Specifications subject to change without notice!



New Tension Meter


With one click you can download the information sheet for our new tension sensor.


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