Jacobs Vehicle Systems develops engine braking and other valvetrain systems for the heavy-duty trucking industry. The goal for this project was to design a new test rig that would reciprocate the valvetrain like it would on an engine and allow the braking components to be exposed to full cylinder pressure loading similar to real-world conditions. The new test rig utilizes a spring pack system and two cams to apply the loading. The standard valvetrain cam actuates the rocker while the auxiliary cam, which was designed by the team and custom built for this project, compresses the springs to achieve the desired load. The rig has been designed to fit onto an existing JVS test stand, which means that a new test stand will not have to be built. Throughout the design, safety was a big concern since these parts could experience up to 10kN of loading. To this end, the entire rig is surrounded by 1-inch-thick plating to prevent parts from being ejected during a system failure. In order to prevent failure in the operation of the rig, a safety factor of 4.0, which is the level recommended by JVS, was met or exceeded for all critical parts. This means that all critical parts can handle at least four times the load they are predicted to experience. Additionally, a design margin of 2.0 was met or exceeded for mean and alternating stress on all Goodman curves to ensure infinite life for all critical parts. Lastly, this rig was designed such that it is compatible with any OEM valvetrain system. This gives JVS the ability to be flexible in their testing needs as they supply braking systems to multiple OEM’s globally and no two systems are the same. This rig adds value to JVS by allowing them to test their engine brake rockers to full loading scenarios safely and effectively without the risk of damaging an expensive prototype or test engine. Jacobs Vehicle Systems will be able to use this rig to optimize their braking systems and continue to provide the best products to their customers.