A vacuum substrate transport apparatus including a frame, a drive section having a drive axis, at least one arm, having an end effector for holding a substrate, having at least one degree of freedom axis effecting extension and retraction, and a bearing defining a guideway that defines the axis, the bearing including at least one rolling load bearing element disposed in a bearing case, interfacing between a bearing raceway and bearing rail to support arm loads, and effecting sliding of the case along the rail, and at least one rolling, substantially non-load bearing, spacer element disposed in the case, intervening between each of the load bearing elements, wherein the spacer element is a sacrificial buffer material compatible with sustained substantially unrestricted service commensurate with a predetermined service duty of the apparatus in a vacuum environment at temperatures over 260° C. for a specified predetermined service period.