Image forming apparatus

1. An image forming apparatus having an image forming portion for forming an image on a sheet comprising:

a housing configured to accommodate the image forming portion;

a cassette configured to be inserted into and drawn out from the housing; and

a conveying mechanism configured to at least partially define a conveying path for guiding the sheet to the image forming portion, wherein

the conveying mechanism has a first conveying element including an upstream end on which a feeding assembly for feeding the sheet is formed, and a second conveying element confronting the first conveying element to form the conveying path in cooperation with the first conveying element, the second conveying element includes an upstream element extending along a sheet feed direction, and a pivotal downstream element connected to the upstream element,

the housing includes a rail configured to guide the second conveying element from a first position where the second conveying element forms the conveying path along the first conveying element to a second position where the second conveying element is away from the first conveying element, the rail includes a first rail configured to guide the upstream element when the second conveying element is displaced from the first position to the second position, a second rail configured to guide the downstream element when the second conveying element is displaced from the first position to the second position, and a third rail configured to guide the cassette to be inserted and drawn out, the first rail and the second rail join together with the third rail, and

the second conveying element located in the second position is configured to be guided by the third rail to move in a direction where the cassette is inserted and drawn out.

2. The image forming apparatus according to claim 1 , wherein

the first rail includes an upstream wall inclining in an upstream direction from the first position to the second position, and a downstream wall inclining in a downstream direction from the first position to the second position, and

the upstream element includes a first boss guided by the first rail.

3. The image forming apparatus according to claim 2 , wherein

the second rail extending from the first position toward the second position inclines along the inclined upstream wall, and

the downstream element includes a second boss guided by the second rail.

4. The image forming apparatus according to claim 3 , wherein

the third rail includes a first section configured to guide the first boss, a second section configured to guide the second boss, and a confining portion formed between the first section and the second section, and

the confining portion confines movement of the second boss toward the first section.

5. The image forming apparatus according to claim 3 , further comprising a positioning mechanism configured to position the upstream element of the second conveying element existing in the first position.

6. The image forming apparatus according to claim 5 , wherein the positioning mechanism includes:

an engaging hole formed in the first conveying element;

an engaging piece retractably attached to the upstream element, the engaging piece coming into engagement with the engaging hole; and

a biasing member configured to bias and protrude the engaging piece from the upstream element.