1、分析說液壓閥芯和閥體在使用時不斷產生磨損，使得零件尺寸、形狀和表面質量發生變化，液壓閥中的平衡彈簧、閥芯及閥座，在長期變載荷下工作，產生疲勞及裂紋，造成彈簧、折斷或閥座密封表面剝落、損壞。
Lift manufacturers and analysts say hydraulic spool valve in the use of the continuous generation of wear and tear, making the part size, shape and surface quality changes in the balance of the hydraulic valve springs, valve and valve seat, working in long-term variable loads, fatigue and crack, causing the spring, break or seating surface spalling damage.

2、介紹液壓閥零件加工過程中殘留的殘余應力和使用過程中的外載荷應力，超過零件材料的屈服強度，零件產生變形，液壓油中混有水分或酸性物質過多，使用較長時間后，腐蝕液壓閥中的零件，使其喪失應有的精度。
After the introduction of hydraulic valve lifter manufacturers parts processing residual residual stress and use external load stress, the yield strength of the material than the parts, parts deformation, hydraulic oil mixed with too much water or acidic substances, the use of a longer time corrosion of hydraulic valve parts, due to the loss of precision.

3、升降機在液壓閥制造或修理時，沒有達到規定的技術要求，閥芯與閥套間液的徑向力不平衡，最終使閥芯壓向閥套內壁面出現卡緊現象。
When the hydraulic lift valve manufacture or repair, did not meet the technical requirements, the radial force of the valve spool suites liquid imbalance eventually appear clamping pressure spool valve comprising a wall to the phenomenon.