Does anyone have a suggestion on how to secure the Ford ring gear to the
 reduction housing? Milo


 You can try this trick.
 Make the housing bore about .1 inch larger in dia. than the OD of the
 ring gear. Glue the ring gear in the housing with red RTV.

 Drill eight holes in the  pattern shown in the picture.
 Use 5/16 18 tap drill "G" size drill.

 Drill the "G" 0.2610 dia. tap drill holes down into the OD of the ring
 gear about .150 to .2 inch.
 The ring gear is .3 inches thick before you get to the base of the gears.
 Overall thickness is .4 inches including the height of the teeth.

 Tap the holes in the aluminum housing with an ordinary 5/16 18 tap as
 far as you can.
 Chase the treads with a 5/16 18 bottoming tap to the end of the aluminum.

 Turn down the treaded end of the socket head 5/16-18  screws .1 to .15
 inches long to a diameter of .2 inches. Start at the ends of the threads .
Or buy them. See the extended point screw  attached jpg from McMaster.

 These studs will serve as a fail safe in the unlikely event the RTV bond
 fails in shear.

 This gives a bit of cushion to the ring gear as planetary's are self
 aligning.

 Drill the head of the screws and safety wire them.

 Paul Lamar

 BTW Milo. Install the ring gear last. Attach the planet carrier to the
 output prop shaft first.
 While the RTV is not yet curred rotate the prop shaft and planet carrier
 to center the ring gear
 in the RTV and housing. Then let it cure.

 Paul Lamar

Paul a couple questions,

We have machined the box housing .10 to accommodate the ring gear, and the RTV for cushioning.

If I understood you correctly the RTV will carry the torsional load, the set screws are there just in case the RTV shears, is that correct?

I assume that the set screws do not make contact with the ring gear in normal operation, is that correct?

We have devised a method to notch out the ID of the housing and the OD of the ring gear to increase RTV shear strength. Is this a good idea?

We would like to test the drive with only the RTV carrying the shear load! Your thoughts! We can always install the set screws later.

We request one and all to suggest methodology for assuring that no voids occur in the RTV at time of installation. Milo


Won't hurt to test it on the ground but I would use the set screws in the flight hardware.


Paul Lamar

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