I would like to bypass the remote control receiver on a ceiling fan and was wondering how the 4 wires leading to the fan control the speed and direction of the fan. Is one of the wires the neutral and the other three for the 3 different speeds. If so, how does the fan reverse direction? Does it reverse the polarity? Seems like hampton bay and hunter fans have very similar configurations. Thanks for any help.

Probably like the Type 1 circuit here:

Ceiling Fand wiring Diagrams

In simple terms the speed is goverend by a dual capcitor. Capacitance adds in parallel. Thus you get 2 speeds, Cap A; Cap B and cap A||B or A in parallel with B. The last is the highest speed.

The other winding, the polarity is reversed, using a DPDT switch in a polarity revering configuration.

Note that there are different types of motors.

Look at CeilingFanParts.com Home for additional info.

Bypassing a remote receiver is not an easy task if the fan does not already have pullchains, and I do not recommend it.

Ceiling fans use PSC motors, usually the reverse feature operates by switching which coil is wired to the capacitor. In some cheaper motors, the coil wiring is switched rather than the capacitor.