The I-beam has a hole drilled which just provides clearance for a 2-1/2 inch long, 1/2 inch NPT, schedule 40 pipe nipple.

The nipple has a coupling on each end. The top side of the top coupling is fitted with a cord grip. The bottom side of the lower coupling has another short pipe nipple to aid in assembling the "bearing."

There is a 7/8" flat washer between the top coupling and the I-beam.

The lower end of the 2-1/2" nipple passes through a 1-1/2 inch pipe end cap and is held in place by the lower coupling.

Two Teflon washers were cut from a piece if flat material and are stacked between the I-beam and pipe to provide a low friction bearing surface.

Wires from the generator run down through the pipe nipple bearing since there are reports on the internet that the winds tend to blow generators both directions more or less equally and wires do not need to be untangled very often. If twisting becomes a problem, I will make changes then.

Updated 5-7-06
Hello, Terry,

It has been a long time getting this to you and I realize you may no longer need it but I decided to send it in case you wanted to add some more detail to my generator you put on your site.   

I built the generator with an electronic 2-stage braking system installed but it produced some objectionable electrical switching noise and I jumped it out.

The electronics first loaded the generator with resistors then switched a set of relay contacts across the generator output if voltage continued to increase.

The wires running down through the pipe have not twisted apart.  I will check on them again in the early spring.  The generator is still up and functioning.

I hope you are doing well and the posting of my pictures looks good.

Generator Construction

The hub is fastened to the shaft arbor with double nuts to prevent loosening with vibration.
The generator is a 30 Volt Ametek PM motor purchased from eBay.  It is 4” in diameter and 4-3/4” long with a 5/8” diameter shaft.  It is marked:
 060484K7 01A (E56617) 116253-00 799031-2?? REV J

The motor is mounted to a  1/8” plate welded to an 18” length of  4” steel I-beam. The I-beam section is light weight and has a hole drilled which just provides clearance for a 2-1/2 inch long 1/2  inch NPT schedule 40 pipe nipple.
The nipple has a coupling on each end.  The top side of the top coupling is fitted with a cord grip.  The bottom side of the lower coupling has another short pipe nipple to aid in assembling the “bearing.”
There is a 3/4 flat washer between the top coupling and the I-beam.
The 2-1/2 nipple passes through a 1-1/2 inch pipe  end cap and is held in place by couplings on each end.
Two Teflon washers were cut from a piece if flat material and are stacked between the I-beam and pipe to provide a low-friction bearing surface. 
The “bearing” end cap is screwed onto a section of 1-1/2” pipe that, in turn, drops inside a section of 2” pipe and is centered with three 1/4-20 screws threaded in the pipe at 120 degree spacing.  There is a 2” schedule 80 pipe tee between this section of pipe and the base section which is set in concrete.  The wires come out of the mast through the tee.
The tail was cut from a 24 X 24 inch piece of thin gauge aluminum.  It is 24 inches tall on the back, 8 inches on the front and 24 inches long.  The tail seemed too flimsy and was reinforced with 1/8 X 3/4”aluminum ribs.  Heavier material, without ribs, is recommended.
The tail is fastened to the I-beam with a 3/4 X 36 length of square aluminum tubing and 1/4-20 hardware.
The generator has a sheet metal cover that was bent from 24 gauge galvanized stock.
There is an “O” ring around the shaft, between the motor face and the mounting plate.

There is also a plastic/rubberized seal around the shaft, between the mounting plate and the propeller hub.  It was made from a suction cup hanger drilled just large enough for shaft clearance and held in place with silicone.  There is a hole drilled in the lower quadrant of the suction cup.  Any water that gets in should run out the hole before it gets high enough to reach the motor shaft.

Wires from the generator were routed down through the pipe nipple bearing since there are reports on the internet that the winds tend to blow generators both directions and wires do not need to be untangled very often.  If twisting becomes a problem, I will make changes then.

Generator Performance

This generator was built to keep a 12 Volt, lead-acid battery charged.  The battery  provides power for a 2-way  radio, AM-FM radio and cell phones at a remote hunting camp that has no commercial power.  The power demand is intermittent with most use in November and December.

The wind generator output could be connected directly to the battery but it has enough over voltage potential to damage not only the lead-acid battery but any sensitive electronics connected to the battery.
Therefore, a commercially available charge regulator was added to limit voltage and current going to the battery.  It is an ICP Global Technologies model 10014, marketed for solar panels and  rated 7 Amps.
The Voltmeter normally indicates generator output.  Pushing the pushbutton, PB1, allows the meter to read battery voltage.
My charge regulator keeps the battery from back feeding current to the PM motor.  A diode would be required if the charge regulator had not been used.

I considered adding dynamic braking but decided against it due to the fact that wind gusts of more than 40 mph are rare at the generator site.

The power developed by the generator is proportional to rotor speed.  There is some performance data for Ametek motors used as generators at TLG Windpower but most of it shows output as a function of propeller RPMs.  I could not find any information on the PM motor I was using for this project.

In addition, I was more interested in performance as a function of wind speed so I mounted the generator to the pickup and collected some data while driving down the road.  Unfortunately, there was intermittent wind of approximately 5 to 6 mph on the day I was running the test.   I had to make several runs, in different directions, then average the results.  To summarize what I found:   the generator will develop about 18 Volts in 15 mph wind with no load and about 13 Volts in 15 mph wind with a load of 1.7 Amps.  I was not charging a battery during these tests since the output would depend on the charge of the battery.  The generator output was connected to a  7 Ohm load resistor.  As near as I could tell, the generator will deliver a little under  1 Volt/mph wind after the generator started turning.  Five to six mph wind was required to start the turbine.  Let me say, again, these are approximate numbers that I averaged from several runs up and down the road.  I recorded widely variable output results with the truck moving at the same speed.  I was satisfied that the unit would charge a battery and proceeded to install it at the camp.

Notes: 
1- If you decide to test a generator mounted to a pickup truck, have a good story ready and be prepared to have some fun.  My story was that I was working on a revolutionary new energy conversion device that would kick in and run the truck on wind power at around 50 mph and that I was trying to get it to work at lower speeds.  If you are convincing, you can sell stock in the venture to continue development.
 2- Thanks to www.bioelectrifier.com/mwind for ideas on dynamic braking resistors and Terry Galyon for weatherizing suggestions as well as a lot of other helpful data on his web site:  www.tlgwindpower.com