This TIL applies only to parts shipped before August 15, 2012.

The low-friction moving carriage on the Centripetal Force Apparatus (CFA) should slide freely. Early units did not include a spreader bar to keep the legs apart. On these units, if the carriage has been exposed to heat or is stored with the legs bent inward, the bearings will bind on the spinning arm.

If this happens, the carriage is damaged and cannot be used. Call Vernier for a replacement.

Systems shipped after August 15 2012 include a spreader bar on the bottom to prevent this from happening.

Only the moving carriage requires and includes the spreader. The other, fixed, carriage does not have a spreader.

See also How do I attach the carriages to the Rotating Beam of the Centripetal Force Apparatus?.