In a gear contact as simulated on a roller test machine, the instantaneous coefficient of friction follows the concept of transition from boundary to hydrodynamic lubrication. The coefficient has been found to increase with increasing load and to decrease with increasing sum velocity, sliding velocity, and oil viscosity as each of these quantities is varied individually. The viscosity was determined by the temperature of the oil entering contact and the viscosity-temperature characteristics of the lubricant. The results have been combined in a formula which closely represents the data. When this formula is used in gear scoring calculations, the same type of U-shaped load-speed curve is obtained as has been found on several gear test rigs. *Presented as an American Society of Lubrication Engineers paper at the Lubrication Conference held in Boston, Massachusetts, October 17–19, 1960.

Instantaneous Coefficients of Gear Tooth Friction

The motion of an electrically conducting, incompressible, viscous fluid in the presence of a magnetic field is analyzed for flow between two parallel disks, one of which rotates at a constant angular velocity. The specific application to liquid metal lubrication in thrust bearings is considered. The two field configurations discussed are: an axial magnetic field with a radial current and a radial magnetic field with an axial current. It is shown that the load capacity of the bearing is dependent on the MHD interactions in the fluid and that the frictional torque on the rotor can be made zero for both field configurations by supplying electrical energy through the electrodes to the fluid.

Magnetohydrodynamic lubrication flow between parallel rotating disks

An analysis is presented of the stiffness and damping which may be expected from a rolling element under oscillating conditions. The level of damping, which may be expected from a complete bearing ...

The Sources of Damping in Rolling Element Bearings under Oscillating Conditions

Performance of hydrostatic tilted thrust pad bearings of various recess shapes operating with non-Newtonian lubricant

Inertial effects due to the centripetal forces may become dominant at high rotational speeds in hydrostatic thrust bearings. Although this influence has been recognized in literature, bearings are commonly optimized with respect to the minimum friction, and the dissipation function has not been taken into account in the optimization procedures. It is observed that the secondary flow caused by the inertia term gives a large contribution to the dissipation for applications with a high rotational speed. In this study, the minimum dissipation for annular and circular recess thrust bearings operating at a certain rotational speed is determined by finding the optimum film thickness in the recess. An example is given for annular recess thrust bearings.

J.F. Osterle

Papers

The effect of lubricant inertia in hydrostatic thrust-bearing lubrication

Inertia-induced cavitation in hydrostatic thrust bearings

On the load capacity of the hydromagnetically lubricated slider bearing

On the hydrodynamic lubrication of roller-bearings

Film geometry effects in hydrodynamic gear lubrication