TROLLY CHECKNUT A trolley checknut is a type of nut used in the assembly or maintenance of a trolley. It may be used to secure components, provide a locking mechanism, or enable adjustments in the trolley system.TROLLY CHECKNUT 7 NO.TROLLY CHECKNUT 13 NO. F/T & R/TTROLLY CHECKNUT 12 NO. F/R & R/TTROLLY CHECKNUT 14 NO.