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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. 

## Torque Tubes 

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 

Cable drums are used primarily in trim tab systems. As the trim tab control wheel is moved clockwise or counterclockwise, the 

<img src='content_image/592396.jpg'>

cable drum winds or unwinds to actuate the trim tab cables. [Figure 2-82] 

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