The invention relates to an adjusting mechanism capable of micro-controlling the back lash of a
pinion and a rack, belonging to the technical field of motor steering. The adjusting mechanism capable of micro-controlling the back lash of the
pinion and the rack is constituted by a main body cover, a
pinion shaft, a rack, a support seat of the rack, an adjustment plug, a back lash adjusting worm, acheck pin of the worm and the like, wherein, the pinion shaft and the rack are fixed in the main body cover, and the support seat of the rack, a back lash preloaded spring and the adjustment plug arearranged at one side of the rack. A mounting hole of the worm is opened on the main body cover, in which the back lash adjusting worm is arranged, and the
tail part of the adjustment plug is processedwith splined teeth. The invention utilizes the principle that the worm gear has large drive ratio, thereby magnifying the sensitivity of the back lash accuracy control of a
rack and pinion steering gear by times, correspondingly reducing the used external force when adjusting the worm, and enlarging the controllable range of tolerance clearance. The invention also can be combined with angle and
displacement control equipment so that the clearance control can be automatically finished by the equipment, not only the gap value can be accurately controlled, but also the clearance adjustment can be efficiently finished, and thereby the
process control capability is greatly improved.