Which device is essential for checking the condition of a grinding wheel?

The device crucial for checking the condition of a grinding wheel is the ring tester. This specialized tool is designed to assess the integrity and structural soundness of a grinding wheel. When a grinding wheel is struck with the ring tester, it produces a specific sound; if the wheel is damaged or has internal flaws, the sound will be different compared to a solid wheel. This method is effective in detecting cracks or defects that may not be visible to the naked eye, ensuring safe operation during grinding tasks.

Other options like an air compressor are primarily used for powering tools and do not provide any functionality regarding the condition of the grinding wheel. A measuring tape is useful for measuring distances but does not offer insight into the structural integrity of the grinding wheel. Similarly, a caliper is great for precise measurements of objects but is not intended for evaluating the condition or safety of a grinding wheel. Thus, the ring tester stands out as the appropriate tool for this specific purpose.