With the SMP vacuum vessel now installed inside the shield box, a test was performed to measure the torque required to rotate the vessel.  At a moment arm distance of 2.0m a force of 89N was required to rotate the vessel (with no module installed) resulting in a torque of 178Nm.  Based on this, the coefficient of rolling resistance (CRR) was calculated to be 0.007;  This is fairly close to available data for similar applications such as cast iron wheels on steel rail (https://en.wikipedia.org/wiki/Rolling_resistance).  The CRR used for design of the SMP drivetrain was 0.054 which was based on empirical data for a similar product.  Because this is significantly higher than the friction of the as-built system the drive-train components are stronger than required and should have no problem rotating the vessel when loaded with a module.

Further details and calculations included in the attached PDF.