Exclusive technology developed by and exclusive to DLM the Line Tension Load Pin is specifically designed to be mounted as the centre axle of a sheave wheel which then measures the line tension of the cable running over the wheel.
It uses DLM’s intelligent Sirius amplifier mounted internally in the pin to process signals from the strain gauges in order to determine both the resultant force and the wrap angle. The amplifier uses this to calculate the line tension and outputs this via a 4-20mA signal.
Normally a standard single direction load pin is required to be fitted so that the load is applied in one plane on the pin, and will not produce accurate load readings if load is applied outside this plane, thus when fitting into a sheave they are only able to measure the resultant force and not the line tension. If the angle of wrap changes the resultant force on the pin will change and therefore would not give a true value for line tension.
However, with the DLM Line Tension Load Pin the change in wrap angle and resultant load is sensed and used to calculate the line tension all within the Load Cell. Therefore giving a 4-20mA signal out relating to line tension.
The Line Tension Load Pin is currently designed to work with wrap angles varying from 40° to 130°, see fig 2. However, larger angle spans can be achieved depending on the design and size of the load pin.
The load pin must be placed in a fixed position and it is critical that the wrap angle only varies from one side of the sheave. The load pin requires a fixed datum point from which to measure and therefore requires a fixed cable entry onto the sheave from one side. It is not yet possible to have the wrap angle varying from both sides of the sheave. See fig 3 for a graphical representation.