Job of the NT855 that D85A-18 bulldozer uses diesel engine risks black smoke to stop machine examination to know feebly, engine oil radiator does not have leakage oily phenomenon, oil path also does not have breakdown. Dismantle check engine, discover cylinder bushing has rustily alveolus, proving engine oil enter water tank from rustily aperture. Repair personnel to think because crock wall gap is big,breakdown phenomenon is, compression ratio too small, fuel cannot burn completely what cause. Changed try afresh after the cylinder bushing of engine, piston, piston pin and piston annulus when machine, still when risk the black smoke, exercise that turn land faint. Measure school fuel injector to make clear, injection pressure is inside standard limits, pulverization is good; Pump of desired result PT also did not discover a problem. Dismantle check engine again, discovery when, piston annulus all does not have a problem, but when the height that measuring camshaft cam, discover its have the 2/3 of standard height only highly. The analysis thinks, cam height is reduced because of wearing away, make piston motion fails to burn when position of consummate dead centre, cause ignition delay, make engine risks black smoke, job faint. Change after camshaft, breakdown is able to eliminate. The Ⅳ crock discovers when abnormal knocking dismantles check engine connecting rod bolt when the 6135AZKa that T200 of the card that ask for hill bulldozer uses diesel engine works already was spun a lot of, preliminary conclude, breakdown reason may be connecting rod bolt becomes loose, bring about in force suffers to increase below concussion repeatedly and be out of shape; Also may be connecting rod screw has quality problem. Checked bolt of other connecting rod for this, the result all does not have a problem, its tighten firm moment of force to also accord with a requirement. Change after bolt of this connecting rod, outfit machine movement shows everything is normal, breakdown is eliminated. Understanding arrives later, the connecting rod of crock of the Ⅳ when this machine heavies repair is out of shape somewhat, repair personnel undertook constructional after proper motion is corrective. Accordingly, the real reason that causes this trouble is: Be out of shape as a result of what did not think of connecting rod can make connecting rod bolt produces model to change, bring about its tensile strength to drop, did not change by the regulation just about new connecting rod bolt, and still used old assemble, bring about bolt to reduce and spin because of tensile strength consequently. The TATRA3-929-11 that TATRA815S1 dump truck uses diesel engine produces the phenomenon that hold tile in the arms 1000h ran to happen to hold made of baked clay phenomenon in the arms namely only after this machine heavies repair. After the engine that tear open solution, checked engine oil above all, what this machine uses is engine oil of Great Wall 15W/40CD, although viscosity of the engine oil when high temperature is reduced somewhat but inside normal value, and pollution is spent, value of suspension, PH eligible; Reexamination oil path, phenomenon of the straightway also, oil that do not have leakage. When the lubricating oil pump that tear open check, discover gear end panel and before, the joint face gap between rear cover is too big, arose consequently inside discharge. Because aluminium pledges pump case cannot use grinder rehabilitate, use treatment of planar milling machine consequently, make gear end panel and before, the clearance of rear cover reached mark fiducial value, burnish of reoccupy metallographic sand paper is smooth. Do not have when the experiment after machine of heavy new clothes inside discharge, the job in outfit of the following carry is regular all the time also, explain breakdown already was eliminated. The analysis thinks, the cause that causes this trouble is: Engine is worth the spring with inferior air temperature when overhaul, engine oil viscosity is big at that time, quantity of the discharge inside lubricating oil pump is consequently little, engine oil pressure can amount to normal value, because this repairs personnel oversight to lubricating oil pump detect; Apply man-hour to the summer, the machine issues successive movement to make engine oil viscosity is reduced in high temperature, quantity of the discharge inside engine oil increases, fail to form effective oily film, bring about thereby happened to hold made of baked clay accident in the arms. CNC MillingCNC Machining