An image forming system includes an image forming apparatus and a feeding device, the image forming apparatus including an image forming unit, a housing, an opening/closing door openable and closable between a first closed position and a first open position, and a support unit openable and closable between a second closed position and a second open position and configured to support a sheet when the support unit is at the second open position, the feeding device being movable in a direction horizontal to the image forming apparatus, configured to move to a coupled position and a decoupled position and feed the sheet to the image forming apparatus when the feeding device is at the coupled position, wherein when the feeding device is at the decoupled position and the opening/closing door is at the first open position, the feeding device overlaps the support unit as viewed from a first direction.

An image forming system includes an image forming apparatus and a feeding device, the image forming apparatus including an image forming unit, a housing, an opening/closing door openable and closable between a first closed position and a first open position, and a support unit openable and closable between a second closed position and a second open position and configured to support a sheet when the support unit is at the second open position, the feeding device being movable in a direction horizontal to the image forming apparatus, configured to move to a coupled position and a decoupled position and feed the sheet to the image forming apparatus when the feeding device is at the coupled position, wherein when the feeding device is at the decoupled position and the opening/closing door is at the first open position, the feeding device overlaps the support unit as viewed from a first direction.

An image forming apparatus, includes: a connecting member that connects, in an image forming device body and an extension unit allowed to be connected below the image forming device body, the image forming device body and the extension unit to each other, wherein the connecting member includes a first connecting claw that is locked to the image forming device body, and a second connecting claw that is locked to the extension unit, and includes an operation portion that switches between a locked state and an unlocked state of at least one of the first connecting claw and the second connecting claw, and the operation portion is operable in a direction in which the first connecting claw and the second connecting claw are connected to each other along the connecting member.

An image forming apparatus configured to form an image on a recording material includes a first casing, a second casing connected to the first casing in a vertical direction, a positioning projection provided to the first casing, and a fitted portion provided to the second casing, the positioning projection fitting to the fitted portion. The fitted portion is formed to allow relative sliding movement between the positioning projection and the second casing in a first direction intersecting the vertical direction and to limit a range of relative movement between the positioning projection and the second casing in a second direction intersecting the vertical direction and the first direction when the first casing and the second casing being connected to each other.

A method of easily determining which sheet is conveyed from which sheet storage unit in a case where a test chart is printed on sheets conveyed from a plurality of sheet storage units is provided. The control method includes performing control to convey a first sheet from a first sheet storage unit, printing on the first sheet, based on that the first sheet is a sheet conveyed from the first sheet storage unit, a print test image and first identification information that identifies the first sheet storage unit, performing control to convey a second sheet from a second sheet storage unit, and printing on the second sheet, based on that the second sheet is a sheet conveyed, a print test image and second identification information that identifies the second sheet storage unit.

A sheet containing device is configured such that a driving-side reversal parallel axis gear can be separated from a driven-side reversal parallel axis gear, and imaginary tangent lines 1 and 2 of contact surfaces of a driving-side gear tooth meshing portion and a driven-side gear tooth meshing portion at a position in which the driving-side reversal parallel axis gear and the driven-side reversal parallel axis gear are meshed with each other always intersect with a first imaginary straight line 1 passing through a first rotation axis 1 of the driving-side reversal parallel axis gear and a second rotation axis 2 of the driven-side reversal parallel axis gear through rotation of the driving-side reversal parallel axis gear.