The GO / NO GO plug gauges for trapezoidal threads, tolerance 7H, are inspection tools designed to verify the conformity of internal trapezoidal threads manufactured according to DIN 103. They are used for fast and repeatable checking of nuts, lead nuts, threaded bushes, motion transmission components, lifting devices, linear drive systems and mechanical parts in which trapezoidal threads are used for motion, positioning or load transmission.

The GO / NO GO configuration provides a practical and immediate inspection method for internal threads. The GO side must screw correctly into the thread, confirming that the thread meets the minimum acceptance requirements and is suitable for mating with the corresponding trapezoidal screw. The NO GO side, on the other hand, must not enter beyond the prescribed limit, helping identify oversized, deformed, out-of-tolerance or non-conforming threads. This inspection system is especially useful in production and quality control departments because it allows the functional thread condition to be checked quickly without complex measurement procedures on every single part.

Trapezoidal threads are widely used in mechanical applications where strength, load capacity and reliable engagement are required, such as screw jacks, feed screws, adjustment systems, drive elements and translation devices. Correct checking of the internal thread is essential to ensure smooth running, correct functional clearance, uniform engagement and reliable screw-nut system performance. Tolerance 7H represents a commonly used reference class for standard internal trapezoidal threads, while the normal series according to DIN 103 defines the most common geometries and dimensional combinations.

The correct gauge must be selected according to nominal diameter, thread pitch, reference standard and tolerance class required by the drawing or machining process. It is important to distinguish these gauges from those for ISO metric, pipe, UNC, UNF or trapezoidal threads with different tolerances, because profile, pitch and mating function are not interchangeable.

For reliable inspection, the gauge must be used on a perfectly clean thread, free from chips, burrs, oxidation or machining residues, and it must be screwed in while maintaining proper coaxial alignment with the threaded hole. Forced or misaligned use may affect the inspection result and damage both the gauge and the inspected component. These GO / NO GO plug gauges are suitable for mechanical workshops, machine builders, CNC departments, quality control, industrial maintenance and the production of components for linear motion and mechanical power transmission, where simple and repeatable verification of internal trapezoidal threads is required.

On request, the product can be supplied with Accredia certification or, alternatively, with a calibration report; this documentation may delay delivery because the item has to be sent to the inspection or certification body.