Preventive maintenance of rolling stock

The test and maintenance of electrical components on rolling stock is not an easy job to do. Some maintainers dismount some of the parts and bring them to a central location for revision and maintenance. This is a cumbersome and time consuming exercise. In many cases, the electrical parts are replaced only when they break down and are not subject to periodical testing. This of course holds a risk as some parts, e.g. circuit breakers, are crucial for safety reasons.