My company has Taiwan of a China assist the dragon door that grand industry Inc. produces machining center, model HB, 3190S, time of put into production in June 2011, already used 4 years up to now (see a picture 1) . Graph broach of this equipment occurrence main shaft is less than 1 near future a phenomenon, disassemble ram shield examination makes the gap between crock of knife hydraulic pressure and dish reed axis, discover clearance increases apparently (make clear in the manual tag clearance to be 14mm, the examination is 20mm now) . Preliminary judgement this trouble causes by the following kinds of reasons: ① 4 valvular pull claw to shake internal perhaps foreign matter much. The dish reed exhaustion with taut ② has disintegrate appearance. ③ pulls hammer attaint. Disassemble main shaft undertakes checking (see a picture 2, graph 3) , check taut dish reed to have above all without fatigue disintegrate phenomenon, do not have disintegrate problem via examining; Reexamination is pulled claw and pull a hammer, will pull from inside the aperture inside main shaft the hammer goes out with the discharge that pull claw, discovery pulls claw not to have a problem, and pull a hammer to have disintegrate problem (see a picture 4) , this whorl outside pulling hammer model to be BT50-45 ° , manufacturer is Chinese Taiwan selects treasure produces. Graph 2 main shaft pursue axis of 3 dish reed pursues what 4 need to notice is: Because ① pulls hammer disintegrate from the discharge inside main shaft claw and difficulty is compared when pulling a hammer, cannot anxious, systole of the mouth outside needing to will pull claw arrives after proper size, ability is taken out from the Kong Zhong inside main shaft. Form of the whorl outside ② BT50-45 ° 4 valve pulls claw is one a complete set of, include to pull nail and pull claw. Buy one a complete set of to undertake changing then, the problem is able to solve, if the graph is shown 5 times,pull claw newly. Graph 5 new cycle help ungual unit: Author of limited company of Shandong exquisite Electromechanical: Liu Yubo CNC Milling