Trolley jack (1; 101; 201) comprising a main body (2; 102; 202) with respect to which a lifting element (3; 103; 203) is capable of moving up or down for lifting a heavy object, a lever assembly (4; 104; 204) capable of projecting upwards from the main body (2; 102; 202) along a longitudinal axis (5; 105; 205) for allowing a user to manually push and move the jack (1; 101; 201), and a lower end (4c; 104c; 204c) of the lever assembly (4; 104; 204) is connected in an articulated manner to the main body (2; 102; 202), said connection being articulated with respect to a transverse axis of rotation (8; 108; 208), the lever assembly (4; 104; 204) being capable of being lowered with respect to said transverse axis of rotation (8; 108; 208) and arranged against the main body (2; 102; 202), characterized in that: - the main body (2; 102; 202) comprises a portion to which the lower end (4c; 104c; 204c) of the lever assembly (4; 104; 204) is connected, - the portion comprising two inverted L-shaped channels arranged symmetrically on respective opposing sides of the portion, both channels comprising a longitudinal segment and a transverse segment, a rod passing through the channels, such that when the rod is located in the longitudinal segment, the jack is in the position in which the lever assembly is not capable of rotating with respect to the transverse axis of rotation nor with respect to the longitudinal axis, whereas when the rod is located in the transverse segment, the jack is in the position in which the lever assembly can be lowered with respect to the transverse axis of rotation and can also rotate with respect to the longitudinal axis, such that the lower end of the lever assembly is connected in an articulated manner to the portion, and the lever assembly is capable of adopting several longitudinal positions with respect to said portion: one position in which the lever assembly is not capable of rotating with respect to the transverse axis of rotation nor with respect to the longitudinal axis; one position in which the lever assembly can rotate with respect to the longitudinal axis; and one position in which the lever assembly can be lowered with respect to the transverse axis of rotation, for folding the lever assembly against the main body and reducing the total space occupied by the jack; and wherein the position in which the lever assembly can be lowered with respect to the transverse axis of rotation and the position in which the lever assembly can rotate with respect to the longitudinal axis are the same position. - the main body (2; 102; 202) comprises a portion to which the lower end (4c; 104c; 204c) of the lever assembly (4; 104; 204) is connected, - the portion comprising two inverted L-shaped channels arranged symmetrically on respective opposing sides of the portion, both channels comprising a longitudinal segment and a transverse segment, a rod passing through the channels, such that when the rod is located in the longitudinal segment, the jack is in the position in which the lever assembly is not capable of rotating with respect to the transverse axis of rotation nor with respect to the longitudinal axis, whereas when the rod is located in the transverse segment, the jack is in the position in which the lever assembly can be lowered with respect to the transverse axis of rotation and can also rotate with respect to the longitudinal axis,