Pull Test
The pull test is a method of mechanically verifying whether a crimped terminal really grips the conductor. The cable and the terminal are pulled in opposite directions; if the conductor slips out of the barrel, the crimp is invalid. In its simple form it is done by hand, and in its controlled form with a force-gauge rig.
The quality of a crimp cannot be fully judged by eye, because the actual contact is inside the barrel. The pull test closes this blind spot: if sufficient pressure has been applied, the bond between conductor and barrel withstands a force approaching the breaking strength of the cable itself.
- Field application: hold the cable in one hand and the terminal in the other and pull steadily. If the end slips, either the die is wrong or the cross-section does not match.
- Sample method: in series assembly one sample from every batch is crimped and destructively tested, and the remaining ends are then produced in series.
- Together with visual inspection: the insulation should be visible at the back of the barrel and the wire ends at the front.
Do this test not at the end of the installation but as soon as you crimp each terminal. Finding a bad end in a bundle that has been placed in the cabinet, run inside conduit and gathered with cable ties takes hours; a five-second pull check at the moment of crimping eliminates the same fault before it ever appears.
Context in which this term is used: DC motor and driver fault diagnosis matrix