The telescopic device of self loading mixer is a special mechanism used to meet different construction requirements by changing the length of its telescopic pipe and then controlling the inclination angle or height of the discharge chute. Its structural forms include spring telescopic type, hydraulic driving type and hand screw telescopic type.
1.彈簧伸縮式伸縮裝置。彈簧伸縮式伸縮裝置主要由內管、外管、伸縮彈簧和限位裝置等組成。該結構運用伸縮彈簧助力原理，在進行伸長作業時起到助力作用，在特定程度上降低了操控者的勞動強度；在進行收縮作業時需克服彈簧阻力，操控性降低。彈簧伸縮式具有結構簡單，成本低等優點，但存在勞動強度較高，不易操作等缺點。
1. Spring telescopic device. The spring telescopic device is mainly composed of inner tube, outer tube, telescopic spring and limiting device. The structure uses the principle of telescopic spring to assist in the extension operation, which reduces the labor intensity of the operator to a certain extent; The spring resistance should be overcome during the contraction operation, and the controllability is reduced. The spring telescopic type has the advantages of simple structure and low cost, but it has the disadvantages of high labor intensity and difficult operation.
2.手搖絲杆伸縮式伸縮裝置。手搖絲杆伸縮式伸縮裝置主要有外管、內管、絲杠、絲母和軸承等組成。該機構運用螺旋副傳遞運動原理，螺母與螺杆相對位移實現結構的伸縮。與以上2種形式相比，手搖絲杆伸縮式具有結構簡單、便於操作、勞動強度低等優點，故在自上料攪拌車應用較為廣泛。
2. Hand screw telescopic device. Hand screw telescopic device mainly consists of outer tube, inner tube, screw, screw nut and bearing. The mechanism uses the principle of transmission motion of screw pair, and the relative displacement of nut and screw realizes the expansion and contraction of the structure. Compared with the above two forms, the hand screw telescopic type has the advantages of simple structure, easy operation and low labor intensity, so it is widely used in the self feeding mixer.
3.液壓驅動式伸縮裝置。液壓驅動式伸縮裝置通過液壓能驅動液壓缸伸縮完成結構的伸縮，自動化程度得到提高，降低了勞動強度，但需配備獨立的液壓驅動係統，提高了製造成本。
3. Hydraulic driven telescopic device. The hydraulic driven telescopic device can drive the hydraulic cylinder to expand and expand to complete the expansion and contraction of the structure. The degree of automation is improved and the labor intensity is reduced. However, it needs to be equipped with an independent hydraulic drive system to increase the manufacturing cost.
