Checkline RTM 20D - Manual (Page 7)

5 Measuring Practice
5:1 General
Measurements using the RTM 20 D can be made in two different ways:
1. The rope to be measured is loaded to the force X. The RTM is installed
and the tension value is read on the display.
2. The RTM is installed on the rope when it is slack. Then the rope is loaded
to the force X. After that the tension value is read on the display.
Experience has given that a better measurement result is obtained when using method
1
above.
All RTM s (”Rope No.”s) are normally calibrated for measuring according to method 1,
i.e. measuring on an already tensioned rope.
5:2 Various types of ropes
On the sign at the handle of the RTM the max rope dimension (diameter) is engraved,
decided from the range of the outer rope supports. The limit for usable min rope dimen-
sion is more approximate. You can find some guidance under Technical Data chapter 2.
For multistrand (flexible) ropes you normally obtain good accuracy, even if the diameter
or/and the number of strands differ some from the calibration rope.
When it comes to measurements on rigid ropes with few strands (e.g. stay ropes)
the non-accuracy will be large if the diameter or/and the construction of the rope differ. It
is specially obvious for thick stiff ropes.
You get the best accuracy when measuring on a rope identical to the calibration rope.
5:3 Measuring on a tensed rope (check)
The instrument is normally calibrated for measuring on an already tensioned rope
according to method 1 above.
First you select correct “Rope No”, depending on which rope you are going to make
measurements on. The RTM then should be mounted/tightend to the tensed rope. The
measurement result on the display shows the tension force in the rope. It is often suit-
able to perform a few more measurements at different spots on the rope.
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