Ultralow all-plastic central control wheel

An ultralow all-plastic central control wheel comprises a supporting seat assembly, an outer rolling wheel assembly and a control assembly, the supporting seat assembly comprises a supporting seat upper shell and a supporting seat lower shell, the supporting seat upper shell is provided with a containing cavity internally provided with the control assembly, and the control assembly comprises an adjusting cam, a main shaft, a sleeve, a gasket, a bearing, a limiting clamping ring and a locking base. A bottom bracket and a bayonet socket are arranged on a lower shell of the supporting seat, a brake block is arranged on the bottom bracket through a small spring, brake teeth are arranged at the two ends of the brake block, the bayonet socket is connected with a locking base through a second spring, a brake lever is arranged in an inserting groove in one side of the locking base, and the end, away from the locking base, of the brake lever abuts against the brake block. The bottom bracket is provided with an outer r