inspection
is you want to check the minimum lining thickness
minimum lining thickness is done by
taking a depth gage
or any other type of device that you can measure the depth on
so the minimum lining thickness allowable is one thirty second about the
red letter pointing kilometers about the rivet
and uh...
you wanna measure that; record that
on your safety standard inspection sheet
so you just basically put it over top of the rivet
there
Push down and it will tell you the depth
depth remaining above the rivet
if it's all bonded lining in other words glued here to the table
then what you would have
you have to measure from
the top of the lining down to the table
and your allowed two thirty seconds or one point five millimeters above
for that style we've got riveted linings got lotsa lining on their
We're make sure that the linings are tight to
the table here
not rust jacked up out of the way
that the lining is solid all the way through and not cracked
all the way through
a little bit of wear
on a used lining is normal just as long as its not
Severe heat checking
or cracking
on there
So what we're doing is adjusting up the
micrometer
and on here we have
the size dimensions so we set it to sixteen and a half inch
So, sixteen on this one
sixteen and a half on this one and now
in a perfect drum it will come right to zero at sixteen and a half
and any wear that you have
will start to go this way; if it's this way on it
that means that
there's more material than sixteen and a half inches this way is less than
sixteen and a half inches
or oversized; so it's been worn down
and uh... the maximum you are allowed to go on these drums
of an inch over
point one two zero
so if it's more than that the drum has to be replaced
and anywhere
less than that
you know what's going to be your call, based on the rest of the drum condition
but uh... as long as it's not over a hundred twenty thousand it can be put back
into service provided doesn't have any other problems with it
when we load this up
it's really important
any dial indicator that you have
if you let it spring off
is part is on a spring
If you let it come off too quick
it spins the dial around, hits the stop, it knocks it off and throws it out of
calibration so
in this case we would like to do is like to load up that end gently first
put our other end in
and now we just move our micrometer up and down here
and
in that case we got
twenty five thousandths of an inch over
you can check it in several spots if you want
so there were about thirty thousandths of an inch over
size, so plenty of room so we don't
have to worry till we get over the one twenty five now when you take these out
like any dial indicator
you wanna slowly unload the needle on it otherwise you damage it, so
we're going to do is to just gonna push up on the needle a little bit
we're going to pull the bottom out, and slowly release this so it doesn't spin back
and break the needle off.
This is one type of brake drum
gauge that you'll use. There are other different methods of measuring
but this is probably the most common method
and you really need to be measuring the drums on a safety inspection.
So what i'm going to do is, I'm just using a large adjustable
You could use a pry bar down in here
what we'll do is we'll pop the
rollers out of here first
Watch you don't get your fingers
slammed in there
now once those are off
the rollers
we can clean and inspect them. Spend the time and
look at it
examine it. This is the time to order the parts
if needed
not when it's gone back together. And what we're feeling for on here is a
feeling for flat spots
and in fact this one does have some flat spotting
minor flats spotting on it, that you can feel.
I would change those.
They come with the new
shoes
this roller here; We want to check the edges where it wearss on the table
and want to check the face for flat spotting
we do have a little bit of
you can just barely see a flat spot on there now developing
this means that we're going to wear out that, its not going to roll when
the cam turns on it; and that's what you want it to do
that's why when you lubricate these, you
only lubricate the edges here; never the face, if you lubricate the face than
the S cam and as it moves on it'll slide
and that gives you flat spots
Now we are going to take the rest of the brakes apart, and inspect them on the way .
Just grab on to here
just unhook that big front
spring off the front
and then we'll carefully
take the bottom shoe and just wind it back
and there is your
primary shoe off
and now we just pop our secondary shoe off
and
we can have a good look at the table here
uh... for damage on it
any cracks in the welds
and uh...
we have a real good look at the shoe surface
which looks good
we can have a quick look at the springs
there is no tensioning gauges to check the springs. There're just changed
whenever you change the shoes
we can also check the anchor pins here
we want to make sure that these anchor pins are free
and lubricated
now these anchor pins you can lubricate across the face of them as well as the
ends because they want to move in these bushings here in the spider
right; so if they're not moving freely you wanna press those out
and they are
and then uh... are put in news ones that come with your shoe kit