Lawn mower (1) comprising a transport unit (2) and a cutting plate (3) separably assembled, said transport unit (2) includes an arm (26) for coupling to the cutting plate (3), wherein said arm (26) comprises at least one pulley (23) positioned in a front portion of the arm provided with a joint (24) for torque transmission, the cutting plate comprises a shaft (34) suitable to be coupled with the joint (24) of the transport unit and suitable for transmitting in turn the torque to at least one blade (38), a guide frame (31) is fixed in an upper portion of the cutting plate (3) and is adapted to guide the arm (26) during assembly of the cutting plate (3) with the transport unit (2), hooks (22) are provided in a front portion of the arm (26), said hooks being connected to the arm by means of return elements (290), the guide frame (31) of the cutting plate (3) comprises pins (310) suitable for mating with the hooks (22).
