Tension rod mechanism with opposing threads

A tension rod mechanism for a tension rod having a first outer shaft and a second inner shaft slideably received by the first outer shaft and rotatable about a longitudinal axis of the tension rod, the tension rod mechanism comprising:

• a tapered first threaded shaft having a first screw thread with a first thread direction;
• a first collar threadingly engaged with the first threaded shaft, the first collar configured to be received in the first outer shaft for rotational movement therewith and slidable axial movement relative thereto and to apply an outwardly-directed radial force to the first outer shaft;
• a second threaded shaft having a second screw thread with a second thread direction opposite the first thread direction, the second threaded shaft fixedly connected to the first threaded shaft;
• and
• a second collar threadingly engaged with the second threaded shaft and configured to be fixedly received in the second inner shaft for movement therewith,
• wherein, when the first collar is in the first outer shaft and the second collar is fixedly received in the second inner shaft, a first rotation of the first outer shaft relative to the second inner shaft increases the outwardly-directed radial force applied by the first collar to the first outer shaft, and a second rotation in a direction opposite the first rotation increases the axial distance between the first and second collars.