Swashplate
The very heart of the helicopter is the swash plate.
This nifty device allows the main rotor blades to be steered while they are rotating,
and so quick that the blades can be going up when they are at the front of the heli,
and going down when they are at the back of the heli!
I made a cross-section picture of this device, because there appear to be none on the internet.
Attached to the main structure of the helicopter (the cabin so to speak) is the bottom part of the swash plate (green).
This part can be tilted around the center ball, and lifted up and down, and when the pilot does this then the entire swash
(the bearings and top piece) will go with it. This part is press-fitted around a bearing.
Then there is a top piece, partially brass (yellow), partially aluminium (orange).
This part keeps the same orientation as the bottom (green) part because it is connected to the inside of the same
bearing.
The brass piece goes all the way through the bearing inner ring, and seems press-fitted into the inner bearing ring.
In the center there is a ball with a hole drilled through in the vertical direction.
The main shaft driving the rotor blades is going vertically through this ball.
The ball can slide vertically over the main shaft.
At the same time, the entire swash plate can pivot around this ball.
The brass piece has a thicker neck at the top, but not at the bottom.
This neck prevents the ball from coming out at the top.
But the brass has no neck at the bottom.
So after installing the brass piece (so the complete Top piece), the ball can be slided in from the bottom.
After that, a steel Bottom piece is press fitted into the brass piece.
This piece makes the second neck, preventing the ball coming out from the bottom.
This entire bottom part is moving along with the main rotor rotation, but it also follows the tilting and up/down
movements from the bottom part of the swash.