A positioning system comprising a first working element having a first tubular shaft with a first longitudinal center axis and having a receiving section , a second working element having a second tubular shaft with a second longitudinal center axis , an arc element with a holding element and a curved rail extending curvedly along an arc direction , wherein the curved rail is arranged on the holding element and the holding element is configured to be detachably and positively fastened on the receiving section by a fastening element , and a guiding element having a holding section and a guiding section , wherein the holding section is adapted to be guided on the rail and the guiding section is adapted to receive the second tubular shaft and guide it in a center direction perpendicular to the arc direction when the holding section is guided on the rail , characterized in that the holding section has a locking element which is configured for positively securing the guiding element to the rail , wherein the locking element blocks displacement of the holding section in a transverse direction in a locking position and allows displacement of the holding section in the transverse direction in a release position, wherein the transverse direction is perpendicular to the direction of the arc and perpendicular to the center direction, and wherein the fastening element comprises a rocker lever having a first projection at a first end and an actuation surface at an opposite second end , wherein the projection is adapted to engage in a groove (22-1) of the receiving section , and wherein the rocker lever is configured such that the fastening at the receiving section , using the rocker lever can be released or engaged with one hand. a first working element having a first tubular shaft with a first longitudinal center axis and having a receiving section , a second working element having a second tubular shaft with a second longitudinal center axis , an arc element with a holding element and a curved rail extending curvedly along an arc direction , wherein the curved rail is arranged on the holding element and the holding element is configured to be detachably and positively fastened on the receiving section by a fastening element , and a guiding element having a holding section and a guiding section , wherein the holding section is adapted to be guided on the rail and the guiding section is adapted to receive the second tubular shaft and guide it in a center direction perpendicular to the arc direction when the holding section is guided on the rail , characterized in that the holding section has a locking element which is configured for positively securing the guiding element to the rail , wherein the locking element blocks displacement of the holding section in a transverse direction in a locking position and allows displacement of the holding section in the transverse direction in a release position, wherein the transverse direction is perpendicular to the direction of the arc and perpendicular to the center direction, and wherein the fastening element comprises a rocker lever having a first projection at a first end and an actuation surface at an opposite second end , wherein the projection is adapted to engage in a groove (22-1) of the receiving section , and wherein the rocker lever is configured such that the fastening at the receiving section , using the rocker lever can be released or engaged with one hand. <EOS>