Subject: 3.17 ratio
From: rotaryeng
Date: 2/28/2014, 1:11 PM
To: AAA-rotaryeng




           Paul,
                       When you get time.  How do you get 3.17 ratio out of tracy’s
           Redrive.   I have the gears on my bench and can get 2.17 with reverse
           prop turning,  the normal 2.85 with same prop direction, but the 3.17
           has me stumped.  What have I missed??  Neil.

           Normally the ring gear is held and power is taken out of the planet carrier.
           In that case the prop turns in the same direction as the engine.
           Counter clock wise looking from the front of the airplane.

           If that does not work you have the wrong planet set or a measuring error.

           There are three planet sets in the late Ford boxes. Front to back.
           The first is the OD planet set. The next has been historically known as the
           front planet set. And the last the rear planet set.

           The rear planet set looks like this.

           Paul Lamar

           Hi Paul,

           What are the power, RPM and torque ratings for the Ford planetary system?

           Best regards,

           Gordon Gao


           I don't know but the transmission has been used for everything Ford makes
           including the Power Stroke diesel pick up truck engine with 650 foot pounds
           of torque since around 1955. The thing about planetary gears is they are six
           times stronger than  spur gears for the same gear width.

           Here is a P&W gear box good for 30,000 HP.

           Paul Lamar


       Something to take note of on the P&W gearbox. The gears are double herringbone. Then they don't need to worry about end loads. The Ford gearbox has significant end loading that MUST be planned for.
       Bill Jepson

       Bill Jepson

       The Ford gears are not designed for continuous high load as the P&W gears are designed
       for. Automotive transmissions run at low load most of the time with short times of high load.
       The exception is trucks towing. The new Dodge 1 ton´s have a max tow rating of 30,000lbs.
       Roller thrust bearings take care of that thrust load, for all manufacturers.

       Dale Davies


       In 16 years we have never had a gear failure. Some have been 3 pinion versions.

       Paul Lamar

   True, but not 30,000 HP. Another advantage of aircraft use is that there is not the same impact loading
   like automotive experience. Even a turbo charged 4 rotor would not likely harm the gear set.

   Dale Davies




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