升降貨梯http://www.fnae.cn/啟閉機能正常啟、閉閘門，說明控制閥組及液壓站各項功能基本正常；閘門開啟后下滑量嚴重超標，說明啟閉機液壓系統存在較為嚴重的泄漏；無外漏油現象，說明泄漏存在于啟閉機液壓系統內部。根據故障現象和檢查情況分析，泄漏部位應在液壓缸和控制閥組。

1、由于升降貨梯啟閉機運行時間較長，液壓缸密封環和支承結構破壞、磨損、老化以及缸筒內壁拉傷是造成液壓缸內泄漏的主要原因。閘門被提升并鎖定于開閘位置后，液壓系統停止工作，液壓缸進出油道均被切斷，液壓缸有桿腔在閘門自重作用下會建立起一定油壓力，而無桿腔有體積增大傾向，油壓相對外較低，兩油腔間會形成一壓差。
Because cargo lifter hoist run longer, hydraulic cylinder seal ring and bearing structural damage, wear, aging and injury is caused by the inner wall of the cylinder hydraulic cylinder leakage main reason. After the gate is raised and locked in the gate position, the hydraulic system to stop working, hydraulic cylinders are cut out of the oil passages, hydraulic cylinder rod chamber gate under its own weight in certain oil pressure will build, without the rod cavity volume increases tendencies, low oil pressure relative to the outer, will form a pressure differential between the two oil chamber.

2、升降貨梯啟閉機提升閘門至開閘位置后，液壓缸是利用二位插裝換向閥閥芯密封錐面作鎖定。二位插裝換向閥閥芯錐面多次動作后會有一定量的磨損; 閥芯錐面一側為有桿腔壓力油，油壓較高，另一側為冋油道，油壓基本為零；在壓差作用下，液壓缸有桿腔高壓油會通過磨損處泄漏回油箱，形成系統泄漏，使液壓缸有桿腔體積減小，活塞下移，表現為閘門下滑。
Cargo lifter hoist lifting gate to gate position, the hydraulic cylinder is the use of two sealed cartridge spool valve cone as locked. Cartridge valve spool two cone after repeated actions will have a certain amount of wear and tear;spool cone rod chamber pressure side for oil, high oil pressure, the other side of the road for Jiong oil, hydraulic basic zero; in effect under pressure, hydraulic cylinder rod chamber pressure oil will leak back to the tank through the fray to form a system leak, the hydraulic cylinder rod chamber volume decreases, the piston down, the performance of the gate fell.

3、在年久失修下滑量較大的升降貨梯http://www.fnae.cn/液壓啟閉機中，一般液壓缸內泄漏和系統泄漏同時存在，本啟閉機兩種泄漏情況都存在，以液壓缸內泄漏為主，系統泄漏為輔。
Decline in disrepair large amount of cargo lifter hydraulic hoist, in general, the hydraulic cylinder leaks and system leaks exist, this hoist two kinds of leaks are present, the main hydraulic cylinder leak, the system for leaks auxiliary.