Bert Ball Shaft Yoke 240-9 - Various rolling element spline mechanisms have been designed to reduce the axial force required to slip a spline while transmitting torque. While basically higher in cost, they offer numerous advantages which can justify their usage. They show inherently much lower coefficients of friction not only while moving, but also on breakaway or starts. In result the lower thrust pulses and forces on connected components and bearings. The rolling action avoids galling and subsequent interference of mating sliding components and the resultant extremely high thrust forces. Therefore, drivetrain components failures are less apt to occur and it may even become possible to consider lighter components in the connected units. Generally these devices can be lubricated for life at assembly and not require further attention or maintenance. However, in some applications relubrication means are provided.