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A crane load cell can remain electrically healthy while the displayed hook load becomes wrong after re-reeving. The instrument senses force at its installed position, not necessarily the suspended load directly. Changing the rope path, number of supporting parts or sensing location can invalidate the conversion used by the load indicator.
Recheck the crane load cell configuration before changing its span
Start with the crane manufacturer's reeving drawing and the indicator configuration for the new arrangement. Establish what the sensing point measures: a dead-end rope force, a sheave-pin reaction or a force in another structural member. A stored coefficient from the previous arrangement is not a calibration certificate for the new one.
Also establish whether the display includes the hook block, lifting attachment and other suspended equipment. A disagreement equal to an attachment's weight calls for a definition check before a sensor adjustment. Do not use a convenient multiplier to make one test load agree while leaving the configuration unidentified.
| Change | Check | Record |
|---|---|---|
| Reeving | Approved rope arrangement and supporting parts | Drawing revision and selected indicator mode |
| Sheave | Rope directions and bearing positions at the sensing pin | Installed geometry, including changes from the old assembly |
| Hook block | Which suspended components are included in the displayed value | Gross-load and net-load definitions |
| Electronics | Sensor scaling, configuration access and warning functions | Approved settings before and after the work |
A pin specification is not a crane approval
The METRAVON MV-LC0146 is a 3 t load pin with a listed 1 mV/V nominal output. Its radial, double-shear loading arrangement must match the joint design. Neither that capacity nor a successful electrical reading establishes that the pin is suitable for a particular crane or that the complete overload-protection system is approved.
Pin retention, bearing contact and force direction need mechanical review. The indicator must also provide the correct excitation and signal input. Keep these checks separate from the calculation that converts joint force into the displayed lifting load.
Verify the installed arrangement under an approved test plan
Qualified crane personnel should select the reference loads and operating configurations, manage the test area and follow the manufacturer's procedure. Compare several permitted load points rather than only zero and one convenient weight. Record repeat readings and return to zero; investigate a configuration-dependent discrepancy instead of averaging it away.
Questions after a rope change
Q1. Can the old calibration be retained if the pin was not removed?
The pin's calibration may still describe its electrical response to force, but the conversion to hook load needs confirmation. Retain the old settings as a record, not as evidence that a changed rope arrangement is already verified.
Q2. Should the alarm threshold be increased to stop nuisance trips?
No. First establish whether the indicated load and selected crane configuration are correct. Alarm and protective-function settings require authorized review; changing them to conceal a measurement discrepancy can remove needed protection.
Summary
After re-reeving, confirm what force is sensed and how it becomes the displayed load before ordering a new pin. For a METRAVON pin assessment, provide the joint drawing, reeving revision, existing indicator details and recorded discrepancy. Keep crane approval and operational release with the responsible qualified team.
