A variety of testing machines have been developed to test rolling contact fatigue (RCF) and rolling–sliding contact fatigue (RSCF). Many of the RSCF machines have been designed to run at a fixed slide ratio using a geared driveline between the test specimen and the load wheel, which limits the versatility. As more complex stress states are being studied for applications in bearings and gears, the need has arisen for a modular testing machine that could allow the operator to vary both the Hertzian contact stress and the slide ratio to evaluate the effects of contact conditions and microstructure on RSCF. The solution was to build a machine that applies the contact load with a hydraulic cylinder and varies the slide ratio by driving the specimen and load roller through two independent motors, all of which the operator can control through a customizable LabVIEW interface. The equipment was designed around a specimen with a 25.4-mm diameter and a 152.4-mm length. This geometry is large enough to allow evaluation of commercial heat treatments and materials; additionally, it is capable of running two wear tracks on each specimen to reduce the number of specimens required. The hydraulic load application system is capable of developing Hertzian contact stress levels up to 3.2 GPa, with higher stresses possible by altering the load wheel geometry (e.g., crown radius). Damage in the test specimens is characterized postmortem through a variety of techniques. Some preliminary test results are presented to demonstrate the capabilities of the test equipment to evaluate the effects of steel microstructure on RSCF.