To provide a sheet stacking device which improves user-friendliness by automatically determining whether a liftable stacking means (for example, a stack tray) which stacks sheets fed from an image forming apparatus is excessively loaded or out of order, and to provide the image forming apparatus.
A CPU 201 includes a function which when the stack tray 102 is descended after it is determined by a stack tray ascent completion determination means 202 that the stack tray is abnormally ascended, detects overload when descent is determined to be normal by a stack tray descent completion determination means 203 that the stack tray is normally descended, and detects that at least one of the stack tray 102, an elevator 103 and a tray lifting motor 107 included in a tray lifting mechanism is out of order (thereinafter, "out of order" is simply referred too) when the descent is determined to be abnormal by the stack tray descent completion determination means 203.
Toru Kabayama
Shuichi Kudo
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