High developed and sophisticated propulsion systems of heavy tracked vehicles require advanced technologies for indoor testing, measurements and diagnostics. PAISI is the first test stand system that enables simulation of dynamic loads including acceleration and steering of heavy tracked vehicles equal to those in real field operations. The original PAISI has been in use since 1982 at the University of Federal Armed Forces. In the paper, the configuration and capacity of this test stand are explained. Examples for investigations on the test stand, measurements of performance characteristics, simulation of real vehicle operations, diagnostic tests, research and development-investigations and endurance testing are demonstrated and discussed. It is pointed out that PAISI is a valuable tool for tank research, development, testing after production, and diagnostics in maintenance.