Ford planetary gears

Thanks you Gentlemen,

     I will get the CAD drawing done from one these CAD freelancers on the net
     and post back the results.
     .
     Just one question - which of the three SAE 1,2,3 will go with the FORD transmission parts from slausons ?

     Regards
     Zahid Rahman



I saw this photo o various Ford planetary gears on the website, how does each one effect the reduction ratios

The planet carriere with the square theet is 3.12 and the other is 2.85. Hold the ring gear in both cases.
The flange # goes with any gear box. The big flanges are for wood props.

Paul Lamar hold off on the email. I'll be back in a few days.

    You said the planet carrier with teeth is 3.12 and the other is 2.85.
    I was looking at this gear box http://www.aeromomentum.com/gearbox.html <http://www.aeromomentum.com/gearbox.html>
    he described the ratio of his gearbox 2:5:1 Designed for 4 cylinder engine up to 210LB horse power.
    In terms of horse power if that is the correct way to view the ratios what horsepower should be used with 2.85 and 3.12

      Zahid Rahman

    Any HP number.

    Here is a little quiz.
    If I have an engine that generates 200 HP at 6000 RPM what is the torque?

    Paul Lamar

T = (200 hp) 63025 / (6000 rpm)
T = 2101//(in lb_f )/

Zahid Rahman

Correct. Gear boxes are mainly designed based on peak torque.
2100 in pounds is not necessarily peak torque as that usually occurs at a lower RPM.

The main design factor is the length of the line contact between the gears.
That affects the compressive stress in the teeth.

To get and equivalent compressive stress/line length to that of a six pinion Ford planetary
the simple gear box teeth would need to be .875 times 6 or 5.25 inches wide.

Now there is also an optimum diameter to width ratio for gears. The Ford pinion ratio
is about one to one. That means an equivalent simple pinion gear would have to
be about 5 inches in diameter. If the gear ratio was 2.5 to one the large gear would
then have to be about 13 inches in diameter. Obviously that is going to be one
heavy gear box. That is way the vast majority of gear boxes for aircraft engines
are planetary. For frantal area reasons a planetary works much better than
a spur gear box with a Wankel engine.

Paul Lamar

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