小松挖掘機鏟斗缸和左行走馬達工作無力故障的排除與維修

Komatsu excavator bucket cylinder and remove the left running motor fault and repair work to

PC220-5型挖掘機工作8500h后出現鏟斗缸和左行走馬達工作無力的故障，但回轉動作和右行走工作正常，其余動作略顯遲緩。

PC220-5 type of excavator working 8500h after bucket cylinder and left walking motor weakness of the fault, but rotary motion and right walking normal work, other actions are a bit slow.

根據液壓系統圖分析可知，可能引起鏟斗缸和左行走無力的原因有：

According to the hydraulic system diagram analysis, may cause the bucket cylinder and left because of inability to walk:

(1). 控制鏟斗或控制左行走的先導油路故障。

(1). The control or control the bucket left running pilot circuit fault.

(2). 控制鏟斗或控制左行走的控制閥芯卡死或嚴重磨損。

(2). Control the bucket or control the control of walking the left spool stuck or severe wear.

(3). 鏟斗回路安全補油閥卡死。

(3). The bucket loop safety fill valve stuck.

(4). 鏟斗缸、活塞或油封嚴重損壞。

(4). The bucket cylinder piston or oil seal, serious damage.

(5). 左行走馬達故障或中央回轉接頭竄油嚴重。

(5). The left walking motor fault or central rotary joint serious oil leakage.

(6). 主卸荷閥卡死。

(6) the main unloading valve stuck.

(7). 后泵或其控制系統故障。

(7). After the pump or the control system failure.

由液壓系統圖可知，鏟斗缸和左行走馬達都是靠后泵單獨供油的。由于鏟斗缸和左行走馬達同時出現工作無力，因此故障最可能出現在主卸荷閥或后泵及其控制系統上。將前泵、后泵的高壓油管更換，然后試機后發現：鏟斗缸和左行走馬達工作正常，而相后回思索馬達和右行走馬達工作無力。由于說明鏟斗缸和左邊行走馬達及伺服操縱系統工作正常，故障出在為鏟斗缸和左行走馬達單獨供油的后泵或其控制系統。

By the hydraulic system figure, bucket cylinder and left running motor are separate oil supply by pump. Due to the bucket cylinder and left running motor and unable to work, so failure is most likely to appear in the main unloading valve or pump and its control system. Will pump before, after high pressure tubing pump replacement, then the test machine that bucket cylinder and left walking motor work normally, and to consider the right motor and walking motor unable to work. Because that bucket cylinder and walking on the left side of the motor and servo control system is normal, fault a bucket cylinder and left walking single motor oil pump and its control system.

先檢查后泵的控制系統：

After the first check the pump control system:

(1). 由于前泵工作正常，證明前泵、后泵共用的控制先導泵和TVC閥工作正常。

(1). Because the pump is working properly, that before the pump, pump and TVC common control pilot valve after the pump is normal.

(2). 在NC閥出口處裝一個量程為6MPa的壓力表測量該處油壓pi，（因CO閥出口壓力沒有測點），將CO閥調節螺栓緊2~4圈，發現pi上升，再將調節螺栓調回原位，pi下降到原來的壓力。檢測結果符合CO閥工作特性，說明CO閥工作正常。

(2). In the NC valve outlet installed a range for 6Mpa pressure meter to measure the oil pressure PI, for CO valve outlet pressure without a measuring point), CO valve adjusting bolt 4 rounds, found that Pi increased, the adjusting bolt to repatriate the in situ, PI decreased to the original pressure. The results meet the working characteristics of CO valve, CO valve normal work.

(3). 將NC閥調節螺栓調緊2~4圈，發現pi上升，再將調節螺栓調回原位，pi下降到原來的壓力。檢測結果符合NC閥工作特性，說明NC閥工作正常。

(3). The NC valve adjusting bolt tightening ring 2~4, found that Pi increased, the adjusting bolt back in situ, PI decreased to the original pressure. The results meet the working characteristics of NC valve, NC valve normal work.

(4). 拆檢伺服閥時發現：回位彈簧無折斷且彈性良好，連桿機構沒有膠落，閥芯無卡滯和磨損現象，由此說明伺服機構工作正常。

(4). Demolition of the servo valve found: back spring break and good elasticity, linkage without glue down, spool card hysteresis and wear phenomena, which shows the servo mechanism.

由上述檢查結果可知，后泵的控制系統工作正常，鏟斗和左行走無力，只能是后泵本身故障引起的。

By the inspection results show that, after pump control system is working properly, the bucket and left too weak to walk, can only be caused by the fault of the pump itself.

拆下液壓泵總成，經解剖檢查發現：前泵各部分零件完好無損，后泵損壞較為嚴重，柱塞缸端面與配油盤接觸的表面有明顯的溝槽，柱塞缸端面有輕度拉傷，其余液壓元件無明顯的磨損現象。顯然，后泵不能正常工作是因為柱塞缸與配油盤接觸面嚴重磨損，并形成較多的溝槽，造成液壓油嚴重泄漏，使油壓建立不起來，從而導致由后泵單獨供油的鏟斗缸和左行走馬達工作無力。

Remove hydraulic pump assembly, the anatomical examination revealed: before the pump parts intact, pump damage is more serious, the piston cylinder and the end surface of the swash plate contact surface has obvious groove, plunger cylinder face a mild strain and the other hydraulic components without obvious phenomenon of wear and tear. Obviously, after the pump can not work normally is because the plunger cylinder and swash plate contact face serious wear and tear, and the formation of more channels, causing hydraulic oil a serious leak, the pressure built up, resulting in separate pump oil bucket cylinder and left by the walking motor unable to work.

鑒于柱塞缸端面損傷不大而配油盤損壞嚴重，無法修復的情況，我們采用修磨柱塞缸端面和更換新配油盤的維修方案。用手工對研柱塞缸端面和配油盤，使其接觸面積達到95%以上。將研磨好的柱塞缸和配油盤裝配使用，挖掘機工作恢復正常，

In view of the plunger cylinder end damage small swash plate, seriously damaged, beyond repair, we adopt grinding plunger cylinder end and replaced with new oil pan of the maintenance program. Research on hand piston cylinder and swash plate end, the contact area of more than 95%. The good grinding piston cylinder and swash plate assembly, the excavator work returned to normal,

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