A machining assembly that is moveable along a guide track (5) on a machine stand (2), wherein the machining assembly (1) comprises:
- a first electric motor (10);
- a rotatable spindle (11) configured for connection to a machining tool;
- a first transmission system (20) for transmitting torque from the first electric motor (10) to the spindle (11) so as to allow the spindle to be rotated under the effect of the first electric motor (10);
- guide members (12a-12d) configured for engagement with said guide track (5) in order to guide the machining assembly (1) along the guide track;
- a feed gear wheel (13) rotatably mounted to a housing (14b) included in the machining assembly (1), wherein the feed gear wheel (13) is configured for engagement with a cog track (6) arranged on the machine stand (2) in parallel with said guide track (5) in order to allow the machining assembly (1) to move along the guide track (5) by rotation of the feed gear wheel (13);
- a planetary gear (30) arranged in said housing (14b) and having a first gear member (31), a second gear member (32), a planet carrier (33) and several planet gears (34) rotatably mounted to the planet carrier (33), wherein one of said first and second gear members (31, 32) is a sun gear and the other one of said first and second gear members (31, 32) is a ring gear, each planet gear (34) meshing with the first gear member (31) and with the second gear member (32), and wherein the planet carrier (33) is operatively connected to the feed gear wheel (13) so as to allow torque to be transmitted from the planet carrier (33) to the feed gear wheel (13);
- a second electric motor (15);
- a second transmission system (40a, 40b) operatively connected to said first gear member (31) of the planetary gear (30) for transmitting torque from the second electric motor (15) to the first gear member (31) so as to allow the first gear member (31) to be rotated under the effect of the second electric motor (15);
- a manually operated drive mechanism (50) operatively connected to said second gear member (32) of the planetary gear (30) so as to allow the second gear member (32) to be rotated under the effect of the manually operated drive mechanism (50);
- a first rotation restraining arrangement (56) capable of preventing said second gear member (32) of the planetary gear (30) from being rotated by the planet gears (34) in order to allow torque to be transmitted from the second electric motor (15) to the feed gear wheel (13) via the second transmission system (40a, 40b) and the planetary gear (30) and thereby allow the feed gear wheel (13) to be rotated under the effect of the second electric motor (15);
- and
- a second rotation restraining arrangement (46) capable of preventing said first gear member (31) of the planetary gear (30) from being rotated by the planet gears (34) in order to allow torque to be transmitted from the manually operated drive mechanism (50) to the feed gear wheel (13) via the planetary gear (30) and thereby allow the feed gear wheel (13) to be rotated under the effect of the manually operated drive mechanism (50).