The 4-fold rotary union enables the test and set-up station to be supplied with test oil at the same time. The position of the rotating union in the middle between two test specimens (on one arm each) means that one test specimen is set up while the other is being tested. Once the test procedure is complete, the system rotates 180°, allowing the previously set-up test specimen to be tested while the previously tested test specimen is dismantled and a new test specimen is fitted. The simultaneous supply of test and set-up stations significantly reduces the overall duration of the test process. The integrated valve block provides precise control during the entire test run.