Brake caliper flange

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

"Stealth Pilot" wrote in message
...

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.

Then it would seem that you have been carrying 4 unneeded bolts, nuts and
maybe washers around Oz for lo these many years. )

Rich "Why have four when two will do?" S.

Rich S. wrote:
"Stealth Pilot" wrote in message
...

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.


Then it would seem that you have been carrying 4 unneeded bolts, nuts and
maybe washers around Oz for lo these many years. )

Rich "Why have four when two will do?" S.



One thing to keep in mind is that the bolt through the axle, unlike the
ones on the calipers, will get nearly zero twisting moment.

--
----Because I can----
http://www.ernest.isa-geek.org/
------------------------

"Ernest Christley" wrote in message
. com...

One thing to keep in mind is that the bolt through the axle, unlike the
ones on the calipers, will get nearly zero twisting moment.

If properly installed, the brake disk and the mounting flange will be almost
exactly inline. Any twisting moment will be negligible.

See http://temp.corvetteforum.net/c4/elw.../cleveland.jpg

Rich S.

Rich S. wrote:
"Ernest Christley" wrote in message
. com...

One thing to keep in mind is that the bolt through the axle, unlike the
ones on the calipers, will get nearly zero twisting moment.


If properly installed, the brake disk and the mounting flange will be almost
exactly inline. Any twisting moment will be negligible.

See http://temp.corvetteforum.net/c4/elw.../cleveland.jpg

Rich S.



But if all the corners aren't bolted securely, they will not be inline
very long.

--
----Because I can----
http://www.ernest.isa-geek.org/
------------------------

"Ernest Christley" wrote in message
. com...

But if all the corners aren't bolted securely, they will not be inline
very long.

Then use four smaller bolts with the equivalent total shear strength of the
single thru-axle bolt.

Aircraft *must* be light to perform well. One does not build a light
aircraft by ignoring details such as this. A friend of mine built an RV-4.
Before final assembly I remember him going over the airframe and examining
each bolt for proper length. All unnecessary washers were removed and bolts
replaced if they were now too long. Maybe he saved an ounce or two. That's
an ounce or two he doesn't have to cart around for the next few years. At
U.S. Postal rates, that adds up! ;o)

Rich S.

P.S. Yes, I realize that misaligned holes can throw all of the shear force
on one bolt. Drill the *&^% holes right and you won't have that problem.