左侧杆402和右侧杆403上外侧的竖直方向均等间距间隔设置有横杆700，且间距设置为30-35cm(本实施例优选 30cm)；横杆700的延伸方向为水平方向，且平行于背框520；横杆700的长度设置为15cm-20cm(本实施例优选为15cm)，横杆700外套设有防滑橡胶套(未示出)。

通过上述技术方案，使得检修人员在链式升降装置300出故障时，可踩踏横杆700爬出箱体100，属于应急预案，上述横杆700的间距和长度的优选值均是为了检修人员更好的攀爬。

如附图2和附图5所示，左侧杆402和右侧杆403的互相相对的内侧均设置有限位挡块550，且限位挡块550位于同一水平面。限位挡块550设置于升降台500的竖直方向的上方；且限位挡块550与升降台500在竖直方向存在重合区域；限位挡块550的竖直方向的高度低于驱动电机604和旋转齿轮 601的竖直方向的高度。

台湾玉盟齿轮泵1PM5P05R

1PM5P01L

1PM5P02L

1PM5P03L

1PM5P04L

1PM5P05L

1PM1P01L

1PM2P02L

1PM3P03L

1PM4P04L

1PM5P05L

1DG1BP0601R

1DG1BP0602R

1DG1BP0603R

1DG1BP0604R

1DG1BP0605R

1DK1BP0601R

1DK1BP0602R

1DK1BP0603R

1DK1BP0604R

1DK1BP0605R

1DL1BP0601R

1DL1BP0602R

1DL1BP0603R

1DL1BP0604R

1DL1BP0605R

1DG1AP0601R

1DG1AP0602R

1DG1AP0603R

1DG1AP0604R

1DG1AP0605R

1DG1BU0605R

1DG1BF0601R

1DG1BF0602R

1DG1BF0603R

1DG1BF0604R

1DG1BF0605R

1KH1S01L

1KH1S0SL

1KH1S02L

1KH1S03L

1KH1S04L

1KH1S05L

1KH1S06L

1AG1P01R

1AG1P02R

1AG1P01L

1AG1P02L 

1AG1P03L

1AG1P04L

1AG1P05L

1AK1P01R

1AG1P03R

1AK1P02R

1AK1P03R

1AK1P04R

1AK1P05R

1ALP01R

1AL1P02R

1AL1P03R

1AL1P04R

1AL1P05R

1AG2P01R

1AG2P02R

1AG2P03R

1AG2P04R

1AG2P05R

1AG1U01R

1AG1U02R

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通过设置限位挡块550，以限定升降台500可上升的Zui高高度，防止升降台500对驱动组件600产生冲撞。

同时，牵引链条602的长度设置为当所述升降台500上升至Zui高点时所述配重块603仍不与地面接触；防止配重块603触地而干扰升降台500的重力平衡。