How can you ensure mechanical system chains are properly tensioned?

Mechanical systems will give away the answer quickly. In this case our eyes will be the first tool for the job then using manufacturer’s specifications will determine how to proceed using hand tools, measuring and aligning tools. Using the specifications assure to always stay safe before any work, then assure to find slack tolerance and adjusting points. Once you have determined and performed necessary adjustments, don’t forget to do a quality check on the work. When all is done safely and accurately the chain will last its entire life expected time.

For example: drive chains vary greatly in service duty, from light duty, food grade plastic chains in processing machines to very heavy duty high-strength steel chains in mills, foundries and other hot/dirty work environments. Know the application!

In my experience, a chain tensioner is the usual method, possibly with an adjustable spring but usually just a position adjuster. If more advanced measurements are able to be made, good to know. Usually though, full tension is hard to gauge. A torque or force gauge can be used depending on the design.

When working with chain systems, always remember safety first, NEVER checking tension in the chain with mechanical methods when the system is operating, even when it's "low rotation". And noise is the first indicator for failure, check periodically with critical eyes

Lubrication is a matter of routine maintenance, according to design and operational procedures. Under-lubrication can lead to tension problems (from binding, etc.) and other system problems.

There may be gauges or other tools useful for measuring alignment, backlash, wear, etc. always start with routine visual inspections as a part of maintenance. The competent mechanic will observe changes over time to understand if issues are normal wear and tear, or related to an emerging failure mode.

Inspection “before and after each use” may not be possible in a 24/7 operating case. Inspections should be made routinely during operation - often, the operation behavior provides insight into developing issues.