From: Dan Maguire (dmaguire@mchsi.com)
Date: Sat Dec 17 2005 - 18:30:47 PST
Hi TJ,
I am posting this to the list because I learn a lot from reading about
repairs on vehicles that I don't have. When all of the responses go to
only the person asking - it becomes a very dull list.
I've replaced one bogie wheel. Two actually, but I had only started
after one. Here was/is my sequence -
In preparation, take (2) pieces of allthread (see note on size below) -
12" long and weld a nut 1/4" from one end. Thread a second nut on each.
Have some appropriate washers at the ready.
Also have a pile of 6x6 lumber segments 12"-16" long. At least that is
my recommendation - I don't work under things on jacks only. Unblocked
loads (and large volumes of high pressure compressed air) are a phobia
of mine.
1) Loosen the track by the idler nut - a 24" Crescent wrench will come
in handy about now
2) Remove the top roller - these bolts should not be overly tight,
although I am retty sure I went after them with a 3/4" drive ratchet
3) Raise the track as best you can - I got on my hands and knees and
used my back to do it - but I have youth and stupidity in my favor.
4) Insert the allthread sections through the washers and into the hidden
holes under where the top roller was. Engage the threads and start
tightening - you are now compressing the volute spring. Repeat for the
other volute.
5) Jack up the rear end on the side you have been working on. I used a
12 ton jack with absolutely no trouble for one side only. Had to jack
and block a couple of times. Your slides and plates will separate.
6) Lower the HT on your pillar of wood.
7) Tighten the allthread to get the crabs to free float to the degree
that you are comfortable. If you are replacing track - pull the outer
ring of the idler off and pull the track off here - it will only get in
your way.
8) Take off the outer bogie arm.
9) Take off the inner.
10) Wrestle the bogie assy out.
11) Hope that it comes apart easy. I actually had very little problem
getting the bearings and seals out.
12) Press the new in. Fill it with grease while you are putting it
together. Otherwise, given the amount of grease in it, you will end
your evening with the halftrack equivalent of filling a waterbed.
13) [using the Chilton's approach] Reinstall the refurbished parts by
reversing the procedure described above.
Now here are my particular tips and tricks...
a) It may be a good idea to loosen the bogie wheel nuts while the HT is
still loaded on the crab - kind of like you would if you were changing a
tire by the roadside. The bogie is a bit harder to grab onto when it is
rolling around on your workbench.
b) My manual said 7/8" allthread (or 3/4" - I can't remember) but it was
WRONG. I ended up putting a borescope down the throat of the volute to
have a look see. I am glad that I had the borescope and some extra 1"
allthread around, or I would have had to stop my Sunday workfest right
then and there. I think that 1942 and earler were the smaller - 1943
and later were 1".
c) If you know that you will have to pump a ton of grease into the bogie
hub when you are putting it together, it would be reasonable to expect a
ton to come out when you pull it apart. Surprised me, though. Duh.
What a mess! Won't do that again.
d) My roller frame was actually not square to the world. When I went to
put it back together I ended up damaging the inlaid brass on the bogie
shaft. Had to have a welder build it up and a machinist turn it down.
Needed a friend with a 35 ton press to straighten the frame segments.
Moral - after the bearings and seals, the rest should just slide
together. If it does not - DO NOT FORCE IT. Clean it. Straighten it.
Clean it again. But do *not* force it. That brass is just looking
for a reason to go AWOL.
Two pics of interest...
http://dmaguire.home.mchsi.com/bogies.jpg - a diagram for above
http://dmaguire.home.mchsi.com/bogie1.jpg - the task in progress
Anyway, that is the scoop. It is really not that bad of a job. I would
not hesitate to do it again and would be alloting an afternoon assuming
that the frames are straight. There are probably many others with
better insights (Nigel, Wendell, and some others come to mind).
Nigel had this to say to me earlier...
"With most thinks on the halftrack running gear, with the right tools
and once you have done it once, its relatively easy, like changing a
track. We made up a bar that lay across the crab assy with a ratchet
chain to lift up the bogies."
Clever. I am sure it will go well for you.
Cheers,
Dan
Auburn, IN
timothy.smith1@att.net wrote:
> I'd like to report that within the past month I have taken delivery of a complete set of 16 NOS rollers and a set of new 1990 manufactured tracks and an 81mm mortar for my halftrack.
>
> If anyone on the list has "been to see the elephant" on the job of replacing rollers and tracks on a WWII halftrack, I'd sure like to hear about the pitfalls before I get into the job myself.
>
> TJ
>
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