Anchored end Peening Flange Flange ends Torque tube Horn Push-pull rod Quadrant Drum Shaft Control wheel Bearing Figure 2-81.  Torque tube.  Figure 2-80.  Attached rod end. Figure 2-82.  Trim tab cable drum. 2-47 Torque Tubes Cable Drums Another alternative is to place a washer, having a larger  diameter than the hole in the flange, under the retaining nut  on the end of the attaching pin or bolt. This retains the rod  on the bolt in the event of a bearing failure. Where an angular or twisting motion is needed in a control  system, a torque tube is installed.  Figure 2-81  shows how a  torque tube is used to transmit motion in opposite directions.  Cable drums are used primarily in trim tab systems. As the trim  tab control wheel is moved clockwise or counterclockwise, the  cable drum winds or unwinds to actuate the trim tab cables.  [Figure 2-82]