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I am trying to find out how a helicopter rotor's lift is transferred to the chassis. Equivalently, how is the weight of the helicopter transferred to the rotor blades?

While looking for this online, I find a whole array of pictures of the drivetrain. The force enters the main gearbox (MGB), but leaves the MGB with a spinning axle going to the rotor. First I thought that something happens in the swashplate, but that is not well designed for bearing large amounts of force. So my thought is that somewhere in the MGB there is a nice piece of a bearing.

There is a question like this one for airplane propellers: How does the load transfer from a prop to the airframe? The bearings shown there cannot be found in the MGB of a helicopter (or, at least, I could not find them). It seems to me that a helicopter is hanging from its MGB. Can someone help me out? Pictures would be really appreciated.

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The force is transmitted through the mast bearing. Gearbox diagrams often omit that because they're already so complicated.

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The load path is rotor blade to hub, to mast, to mast bearing set inside transmission, to transmission housing, to transmission mounts/struts, to airframe.

enter image description here

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  • $\begingroup$ You might want to add the "Jesus" nut. Called this because if it fails, all the occupants are left to say is "Jesus". $\endgroup$ – Peter Kämpf Sep 28 '19 at 9:23

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