| CAT320BL type excavator walking deviation troubleshooting... | |
Time: 2011-07-21 Hits: 2900 |
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A cat320bl type hydraulic excavator at work after 5100h appeared the following symptoms: when the machine forward 30m, 2m machine has been offset to the left; walking backwards after 30m 2m, the machine also offset to the left. 1, analysis and test The machine is composed of 3 system to realize the drive and control of the main hydraulic system, respectively, pilot hydraulic system and electronic control system. The working principle of its hydraulic system are: driven by the motor directly on, under variable piston pump and gear pump, hydraulic oil pump respectively, since access to the main control valve, a machine not in walking and other movements of the operation, on, under pump hydraulic oil into the tank respectively by the valve body; at this time, to own control valve of the negative feedback signal feedback first, under the pump controller, control, pump swashplate angle, so that the machine idle when the displacement of the hydraulic pump is reduced to the minimum; when walking and other operations, the main control valve in the corresponding pilot pressure oil under the control of the hydraulic pump, the pressure oil to left, right running motor and actuator. The system for the pilot negative feedback constant power variable automatic control system, the maximum working pressure is composed of a main overflow valve control, walking for 34 set pressure. 3mpa. In view of the machine fault phenomena, combined with the hydraulic system working principle, to determine the initial fault should be from the hydraulic system, possible parts: upper and lower main pump and its control system, pilot control valve, a main control valve, central rotary joint and walking motor etc.. In order to faster, more accurately identify the fault location, we carried out the following steps of the test and measurement. ( 1 ) the straight walking test will grab Park in 25m long and flat hard on the site ( see Figure ) at one end, starting the engine, the automatic speed control switch ( AEC ) is disconnected, and the throttle of the engine is placed in the" 10" position, while pushing the left, right running pilot control valve, so that machine straight forward walking about 25m, result 1.3m machine offset to the left; then, push down the left, right to walk first - control valve, so that the machine back straight walking about 25m, find the 1.3m is offset to the left. ( 2 ) the system pressure measuring bucket cylinder piston retracts to the limit position, so that the hydraulic system pressure, the pressure gauge with the measured pressure is 34.3mpa, the relief valve pressure setting. ( 3 ) travel system pressure test release main overflow valve locking screw purity, clockwise rotation of the adjusting screws 1.5 laps, raised the main relief valve pressure test running, overload valve pressure, test method is: plug retaining pin card after the death of the right driving wheel, at the same time with the bucket and arm support right track make it suspended, further manipulation of the right travel control lever, the pressure gauge measured system pressure is under the pump pressure ( 29.5mpa ). ( 4 ) on the rotary joint of the tubing will be central rotary joint under 4 main tubing remove, left, right two to tubing mutually exchanged, tighten after manipulation of the two travel lever ( 1 ) step of testing, testing, find the machine offset to the left. ( 5 ), under the swap on pump tubing will, two pump tubing remove, make, two pump outlet pipe are mutually exchanged, tighten after step ( 1 ) of the test, find the right offset machine. ( 6 ) composite action test when manipulating walking control valve enables excavator linear walking machine, at the same time manipulation of other systems, allowing them to produce action, the results found that the machine does not exist the left leaning fault. 2, diagnosis and troubleshooting According to the above test results and combining with the hydraulic system working principle, can" bleed Division" deduce fault reason: according to: ( 1 ), ( 4 ), ( 5 ), ( 6 ) steps of the test results, can determine the central rotary joint, walk around the motor, pilot control valve and travel main control valve does not exist fault. Because the test step ( 4 ) of the results table, walk around to walk, balance valve, there is no fault running overload valve test steps ( 5 ), and the result indicates that the pilot control valve and travel main control valve and there is no fault. According to ( 2 ), ( 3 ), ( 6 ) steps can be judged on the test results, there is no fault, fault source should be under the pump. Its basis is: ( 2 ), through the test procedure ( 3 ) can preliminary judgment on the work is normal, after step ( 6 ) after the test, there is no fault can be judged on the. Because when the excavator walking machine and control other systems when only the pump oil supply, which can be further described is a pump failure. Then, remove from the excavator hydraulic pump assembly, the pump for repair, overhaul after the discovery, the pump plunger, the plunger sleeve, valve plate are not the problem; pump regulator piston and cylinder are chafing traces, and has a groove. It can be identified, fault reason here. Based on the above, the machine breakdown can be interpreted as: when the machine straight line walking, because under the pump flow regulator of the plunger in a position, and the piston through a pin and the lower pump cylinder mechanical connection, so the cylinder cannot go pump regulator maximum angle position the pump, to form the maximum displacement. At the same time, due to wear more serious, internal leakage, the system pressure can reach 29.5mpa, ultimately resulting in the walking motor speed to slow down, the machine that is offset to the left. Changing parts repair pump regulator after, after again installation test machine table, the fault has been ruled out, the machine to resume normal work. After analysis, the fault reason: because the machine working in windy and sandy desert, when changing the oil hydraulic oil pollution; in addition, the caterpillar company regulations to be replaced after every 500h type hydraulic oil filter core in the work, check the machine repair, maintenance records discovered, in the an oil change period ( 2000h ) had two did not press formulary time to replace the filter element, a total of more than a predetermined time of up to 150h. From this fault can be obtained the following conclusions: Excavator in use, must follow requirements of the specification to choose a qualified oil, pay attention to maintaining the cleanliness of the hydraulic oil, prevent oil contamination when; at the same time, shall be timely replacement of hydraulic oil and filter. The only way to ensure the machine has less failures, prolong its service life |
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