Bellcranks are used to transform control line handle operation into control surface movement. A third wire can additionally operate another control such as a motor throttle control. They come in various sizes for more and less control with different sized airplanes.
3-LINE BELLCRANK SYSTEMS:
The 3-line bellcranks are designed to be used in various application methods. Some mount on the top of bellcrank floor; some mount to the bottom of the floor. There are models that are used for upright and inverted engines to get the more direct routing to the engine throttle. There is also a"span" or "throw": consideration. When using a long span you have less "throw" or movement in the elevator, allowing for smoother control. Also the front lead-out will be your "up" elevator, which can mean smoother taxis, take-offs, flying and landings.
Mounts on the bottom of bellcrank floor and are used when the engine is in the inverted position, allowing you the most direct route to the throttle. When using short span you have quicker "throw" in the elevator, allowing for quicker response.
The Nylon Bellcranks are 2-Line control line systems that control the elevator by the movements of the control handle. Some are glass filled for added strength and reliability. By varying the mounting, the front lead can control the elevator from up or down controlling.
The metal bellcranks are the same configuration as the nylon bellcranks except they are made from metal.
LINEN BASE PHENOLIC MATERIAL BELLCRANKS
These are very strong bellcranks made of 1/8" thick phenolic material. No bushings are necessary.