A tension link replaces a shackle or a section of rigging and measures the force in the line. It is the fastest way to weigh a suspended load without modifying the crane, which is why it is common in ports, construction and offshore work.
Mechanical interface
The cell must match the shackle geometry it replaces: pin diameter, jaw width and the direction of load. A link that is too narrow loads the pin in bending; too wide and the pin bears on the wrong part of the jaw. Always check the working load limit of the assembly against the cell capacity, and remember the cell capacity is a measurement range, not a lifting rating.
Safety factors
Lifting applications require a mechanical safety factor set by the relevant lifting standard, commonly 4:1 or 5:1 on the rated capacity. A cell rated 10 t for measurement may not be rated to lift 10 t. Use cells specifically certified for lifting, with a marked WLL, and keep the calibration certificate with the equipment.
Dynamic loads
Slewing and snatching produce peak loads well above the static weight. Damping in the indicator, and a peak-hold function, help the operator see the real value, but the cell must be able to survive the peaks without damage.
Kevin Huang