Spindle apparatus for use at a machine tool, in particular a lathe, comprising: - a spindle assembly including a workpiece spindle being configured to receive an elongated workpiece and a spindle motor for driving a spindle rotation of the workpiece spindle about a spindle axis of the workpiece spindle; and - a rotary guide-bush assembly (200; 200A) being axially arranged with the workpiece spindle with respect to the spindle axis, the rotary guide-bush assembly including a rotary guide-bush configured to receive the elongated workpiece and being supported at the rotary guide-bush assembly to rotate with the elongated workpiece received in the workpiece spindle about the spindle axis while enabling a movement of the elongated workpiece in the direction of the spindle axis; wherein the spindle assembly and the rotary guide-bush assembly (200; 200A) are configured to connect to each other by a torque transferring connection (500; 500A, 500B; 500C; 500D; 500E; 500F) arranged between the spindle assembly and the rotary guide-bush assembly (200; 200A) along the spindle axis so as to transfer driving torque during acceleration or deceleration of the spindle rotation driven by the spindle motor to the rotary guide-bush of the rotary guide-bush assembly (200; 200A), and wherein the torque transferring connection includes a telescopic coupling tube mechanism having a plurality of tube elements, the telescopic coupling tube mechanism being arranged coaxially with respect to the spindle axis, wherein a plurality of through holes are formed in a tube wall of an outer tube element having the largest diameter among the tube elements of the telescopic coupling tube mechanism, characterised in that the through holes are configured to enable an outflow of cooling and/or lubricating liquid from the inside of the telescopic coupling tube mechanism to its outside. - a spindle assembly including a workpiece spindle being configured to receive an elongated workpiece and a spindle motor for driving a spindle rotation of the workpiece spindle about a spindle axis of the workpiece spindle; and - a rotary guide-bush assembly (200; 200A) being axially arranged with the workpiece spindle with respect to the spindle axis, the rotary guide-bush assembly including a rotary guide-bush configured to receive the elongated workpiece and being supported at the rotary guide-bush assembly to rotate with the elongated workpiece received in the workpiece spindle about the spindle axis while enabling a movement of the elongated workpiece in the direction of the spindle axis; wherein the spindle assembly and the rotary guide-bush assembly (200; 200A) are configured to connect to each other by a torque transferring connection (500; 500A, 500B; 500C; 500D; 500E; 500F) arranged between the spindle assembly and the rotary guide-bush assembly (200; 200A) along the spindle axis so as to transfer driving torque during acceleration or deceleration of the spindle rotation driven by the spindle motor to the rotary guide-bush of the rotary guide-bush assembly (200; 200A), and wherein the torque transferring connection includes a telescopic coupling tube mechanism having a plurality of tube elements, the telescopic coupling tube mechanism being arranged coaxially with respect to the spindle axis, wherein a plurality of through holes are formed in a tube wall of an outer tube element having the largest diameter among the tube elements of the telescopic coupling tube mechanism, characterised in that the through holes are configured to enable an outflow of cooling and/or lubricating liquid from the inside of the telescopic coupling tube mechanism to its outside.