A mounting assembly 10 for mounting a roller brush 12 onto an operating apparatus includes a mounting structure 14 configured to be mountable on the operating apparatus. The mounting structure has a through hole for receiving an idle shaft 16 that is sized to be engageable within a blind hole 42 formed in the adjacent end hub 32 of the brush 12. The idle shaft 16 is resiliently loaded in the direction toward the brush hub 12 by a loader assembly 18 which includes a compression spring 16 acting against retaining ring 48 engaged with the idle shaft 16.