A Hybrid rolling bearing includes an inner raceway and an outer raceway and a plurality of rolling elements arranged therebetween. The outer raceway and the inner raceway are made from bearing steel, having a first surface RMS roughness R.sub.q1. The rolling elements are made from a ceramic material and have second surface RMS roughnesses R.sub.q2,i. At least one of the rolling elements has an increased surface RMS roughness R.sub.q2,N, which is significantly higher than the RMS roughnesses R.sub.q2,i, of the remaining rolling elements. The hybrid rolling bearing can be installed within a refrigerant compressor.

Methods are directed towards dynamically determining refrigerant film thickness at the rolling-element bearing and for dynamically controlling refrigerant film thickness at the rolling-element bearing. Further, an oil free chiller system is configured for dynamically determining refrigerant film thickness at the rolling-element bearing of the oil free chiller system, wherein the oil free chiller system is also configured for dynamically controlling refrigerant film thickness at the rolling-element bearing of the oil free chiller system.

A cooling system includes a refrigerant compressor and a first operating medium, which includes a mixture of refrigerant and lubrication oil. An oil separator reduces the percentage of the refrigerant in the operating medium so that a second lubrication oil enriched operating medium is provided by the oil separator, the provided second operating medium having at least in a second operating state a viscosity ratio of >1.

A cooling system includes a refrigerant compressor and a first operating medium, which provides a mixture of refrigerant and lubrication oil. An oil separator reduces the percentage of the refrigerant in the operating medium to a value between 25% by weight and 80% by weight.

A water lubrication type bearing material contains 12 wt. % to 25 wt. % of a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA resin), 18 wt. % to 33 wt. % of a carbon fiber, and a remainder including a polytetrafluoroethylene (PTFE) resin and/or a modified PTFE resin. The bearing material has excellent wear resistance and sliding characteristics for a water lubrication type bearing.

A ring seal is engaged with a liquid metal bearing assembly and operates to contain metal fluid lubricant leaking through the primary compression seals of a liquid metal bearing to prevent the fluid from entering the high voltage space within the x-ray tube and causing high voltage instability. The ring seal engages the existing configuration for the bearing assembly without deforming the bearing, including effects of thermal expansion and inertial body forces, thus maintaining the tight tolerances for the proper operation of the component parts of the bearing structure. The ring seal retains the leaking liquid metal within the ring seal regardless of the operating state and/or condition of the bearing assembly, such as during operating conditions. i.e., rotation of the bearing assembly or gantry, and non-operating conditions, e.g., shipping and stand-by, and regardless of the corresponding pressures and their locations exerted on the ring seal by the liquid metal.

A bearing system for a control surface of a high speed flight vehicle includes a bearing configured to support the control surface, and a pressurized lubricant chamber containing a lubricant for the bearing. The lubricant contained in the lubricant chamber is in a first phase. The lubricant chamber is subject to heating by a heated aerothermal environment (an environment external to the high speed flight vehicle). The lubricant in the first phase, therefore, is configured to transition from the first phase to a second phase when the lubricant chamber is heated by the heated aerothermal environment. The lubricant in the second phase is configured to flow from the lubricant chamber to the bearing to lubricate and cool the bearing via a flow-based cooling effect.

A structure and associated method for forming a liquid metal or spiral groove bearing assembly for an x-ray tube is illustrated that utilizes a unitary sleeve and a thrust ring or seal each formed of a weldable, non-refractory material. The sleeve and the thrust seal are welded to one another to provide an improved construction for minimizing leaks of the liquid metal bearing fluid. The structure of the sleeve and the thrust seal are formed with deformation restricting features that maintain the integrity of the bearing surfaces of the assembly when the thrust seal is secured within the sleeve and welded thereto to form the bearing assembly.

A cooling system includes a refrigerant compressor and a first operating medium, which includes a mixture of refrigerant and lubrication oil. An oil separator reduces the percentage of the refrigerant in the operating medium so that a second lubrication oil enriched operating medium is provided by the oil separator, the provided second operating medium having at least in a second operating state a viscosity ratio of K>1.

A cooling system includes a refrigerant compressor and a first operating medium, which provides a mixture of refrigerant and lubrication oil. An oil separator reduces the percentage of the refrigerant in the operating medium to a value between 25% by weight and 80% by weight.