Stealth Pilot
July 3rd 03, 12:18 PM
On Mon, 30 Jun 2003 15:19:19 -0700, Chris Hansen
> wrote:
>Anyone know if an AN4 bolt is strong enough in shear so hold a brake
>flange in place on the axle, in other words to stop it from turning due
>to the torque of braking?
>I am fitting new disc brakes on my 1600 lb aircraft (Wittman gear) and
>there is no flange welded onto the axle. Can't weld a new one on as it
>would destroy the temper. The old mount had an AN4 bolt going through it
>and the axle but this 'seems' marginal to me, especially with
>high-capacity units under max braking.
>Attempted to drill out (cobalt bit) the 1/4 in. holes to 5/16 but was
>unsuccessful; the heat-treated steel is just too hard. No luck reaming
>it either.
>The figures I come up are about 4600 lbs for rated bolt shear (95,000PSI
>bolt) while the load on the bolt (in double-shear) for the 5 in. wheels
>at max 1600 lbs, is somewhere around 1600 lbs as well, assuming equal
>braking on both wheels but no tire nor brake slip.
>The aircraft steers with differential braking so everything depends on
>good working brakes.
>The easiest way to fit the new units is to drill the flanges & bolt in
>place like the old ones, with 1/4 in. bolt in each, so if an engineer or
>other knowledgeable person in the group can confirm that this should be
>OK, that'd be great.
>Appreciate any helpful advice, thanks.
>Chris Hansen
Chris the W8 tailwind I fly has 5.00x5 cleveland brakes and hubs.
the flange plate isnt welded to the wittman leg on mine.
there is a piece of tube(about an inch or so long) which is a snug
sliding fit over the inner end of the axle. this has a 4130 "washer"
over it welded to make an annular flange. this tube collar is located
on the axle by a single AN3 bolt.
(btw if my memory is faulty the bolt is definitely no bigger than AN4)
the bolt through the axle intersects the collar twice (once on each
side) so it is in double shear.
the cleveland brake locating plate bolts to the "washer" with 4 AN3
bolts.
has been in use for 500 hours over 18 years.
one tip to save insanity during maintenance.
either make the two fittings absolutely symetrical and
interchangeable,
OR
make them obviously non symmetrical
OR
label the bloody things with a "L" and "R" stamp.
mine are very close to interchangeable but leave the wheel fairings
with a 5 degree difference in incidence if you get the wrong one on
the axle. (of course you then need to dismantle both entire wheel
assemblies to rectify the problem.)
Stealth (dont weaken the axle with too bigger a hole through it) Pilot
Australia
> wrote:
>Anyone know if an AN4 bolt is strong enough in shear so hold a brake
>flange in place on the axle, in other words to stop it from turning due
>to the torque of braking?
>I am fitting new disc brakes on my 1600 lb aircraft (Wittman gear) and
>there is no flange welded onto the axle. Can't weld a new one on as it
>would destroy the temper. The old mount had an AN4 bolt going through it
>and the axle but this 'seems' marginal to me, especially with
>high-capacity units under max braking.
>Attempted to drill out (cobalt bit) the 1/4 in. holes to 5/16 but was
>unsuccessful; the heat-treated steel is just too hard. No luck reaming
>it either.
>The figures I come up are about 4600 lbs for rated bolt shear (95,000PSI
>bolt) while the load on the bolt (in double-shear) for the 5 in. wheels
>at max 1600 lbs, is somewhere around 1600 lbs as well, assuming equal
>braking on both wheels but no tire nor brake slip.
>The aircraft steers with differential braking so everything depends on
>good working brakes.
>The easiest way to fit the new units is to drill the flanges & bolt in
>place like the old ones, with 1/4 in. bolt in each, so if an engineer or
>other knowledgeable person in the group can confirm that this should be
>OK, that'd be great.
>Appreciate any helpful advice, thanks.
>Chris Hansen
Chris the W8 tailwind I fly has 5.00x5 cleveland brakes and hubs.
the flange plate isnt welded to the wittman leg on mine.
there is a piece of tube(about an inch or so long) which is a snug
sliding fit over the inner end of the axle. this has a 4130 "washer"
over it welded to make an annular flange. this tube collar is located
on the axle by a single AN3 bolt.
(btw if my memory is faulty the bolt is definitely no bigger than AN4)
the bolt through the axle intersects the collar twice (once on each
side) so it is in double shear.
the cleveland brake locating plate bolts to the "washer" with 4 AN3
bolts.
has been in use for 500 hours over 18 years.
one tip to save insanity during maintenance.
either make the two fittings absolutely symetrical and
interchangeable,
OR
make them obviously non symmetrical
OR
label the bloody things with a "L" and "R" stamp.
mine are very close to interchangeable but leave the wheel fairings
with a 5 degree difference in incidence if you get the wrong one on
the axle. (of course you then need to dismantle both entire wheel
assemblies to rectify the problem.)
Stealth (dont weaken the axle with too bigger a hole through it) Pilot
Australia