A ball spline having reinforcement bush parts includes a spline shaft having concave track grooves formed to extend along the longitudinal direction thereof; a nut part in which the spline shaft is inserted and movable along the longitudinal direction thereof; and a plurality of balls provided between the nut part and the spline shaft to circulate, wherein: the nut part includes a nut which is a hollow body where the spline shaft is inserted, and retainers which are hollow bodies which are provided at longitudinally opposite sides of the nut and into which the spline shaft is inserted; two spline parts and two reinforcement bush parts are provided at the nut part; some of the balls circulate and move between a track groove and a load track groove and along a no-load circulation part; and the remainder of the balls roll circulate and move along the reinforcement bush parts.

A ball spline includes a spline shaft, an outer sleeve, and two circulation elements. The outer sleeve is slidably sleeved on the spline shaft to form a load channel therebetween for installation of balls, and has an oil guide channel inside. The circulation elements are mounted to two outer end surfaces of the outer sleeve and each has an oil filling hole, an oil storage tank communicating with the oil filling hole, the load channel, and the oil guide channel, and an oil guide portion disposed in the oil storage tank and corresponding to the oil filling hole and protruding towards the oil guide channel. Thus, after injecting lubricant into the oil filling hole of one of the circulation elements, the lubricant lubricates the balls on both sides by means of the oil guide portion and the oil guide channel, thus enhancing the lubrication effect.

A ball spline includes a spline shaft, an outer sleeve, and two circulation elements. The outer sleeve is slidably sleeved on the spline shaft to form a load channel therebetween for installation of balls, and has an oil guide channel inside. The circulation elements are mounted to two outer end surfaces of the outer sleeve and each has an oil filling hole, an oil storage tank communicating with the oil filling hole, the load channel, and the oil guide channel, and an oil guide portion disposed in the oil storage tank and corresponding to the oil filling hole and protruding towards the oil guide channel. Thus, after injecting lubricant into the oil filling hole of one of the circulation elements, the lubricant lubricates the balls on both sides by means of the oil guide portion and the oil guide channel, thus enhancing the lubrication effect.

A linear motion guide unit includes a rail, a slider, and a plurality of balls. The slider includes a coil spring arranged in a first circulation passage so as to extend in a longitudinal direction. The coil spring includes a pair of first regions provided at both ends in the longitudinal direction and fitted in the first circulation passage, and a second region smaller in diameter than the pair of first regions and positioned between the pair of first regions with a gap from an inner wall surface of the first circulation passage.

A ball spline device includes a spline shaft, the outer side wall provided with raceway grooves extending in the axial direction, each raceway groove comprising, a first groove section and a second groove section, and the width of the second groove section being greater than that of the first groove section; a spline nut coaxially fitted over the spline shaft; and first rolling bodies. When the spline nut is located at a first position, the first rolling bodies are located in the first groove sections and in constraint fit with the first groove sections; and when the spline nut is located at a second position, the first rolling bodies are located in the second groove sections, such that the spline nut and the spline shaft have a preset movement amount in the circumferential direction. Further provided are an automated guided vehicle and a stereoscopic warehouse system.