|
Need aimed in the right direction on this.
QUESTION:Quick question, and a little guidance needed here.
Years ago, early 60's probably, a company named Struck, used to
produce a small kit-built bulldozer called a Magna-trac. They are
*still* in business but back then they used to
sell plans, plans & parts, plans & complete kits. These small dozers
had a blade on the front and some other attachments you could get, and
now they are really *fancy*.
My question: I'm interested in how the "clutches" were designed on
these original units. I would imagine that everything is hydraulic
drive on the new ones today, but back then I think they used about a
10 HP B&S engine and belts in some configuration that would work just
like the "big guys". Pushing on the levers - forward, pulling is
backwards and it could spin around in it's own length, but I can't
find anywhere about HOW these clutches were designed.
Can someone either describe this mechanism to me, or point me to a
link that would have the info. I wouldn't even mind buying a set of
the "old time" plans (depending on the price) if I could find a set...
no luck there either.
Thanks for any/all help on this. BTW, years ago, when I was a little
one, Pap bought a small pedal-powered kid's dozer, rubber tracks and
all, that I believe was made by NAPA (Standard Auto Parts) that simply
used a "foot" that would lift up one side of the dozer and provide a
pivot point for the other track to "walk around". This isn't a design
I'm looking for, but real, genuine bulldozer mechanisms.
ANSWER: I'm ignorant of the Magnatrac guts but am familiar with the clutch mechanism
in a similar vintage and class of equipment. The 60's Bobcat skid-steers
use simple clutches for forward and reverse on each side. Two levers, four
clutches. The actual construction looks a lot like an automotive manual
transmission clutch but they run in an oil bath and I don't know if the
clutch pads are a different material on account of that. Actually the oil
bath is 20 gallons of ATF, i.e. the hydraulic reservoir, that is where the
clutches are located on each side, and perhaps that is why the hydraulic
system runs on ATF instead of ordinary hydraulic oil.
As for the clutch actuation, each drive lever is linked by chain and
sprockets to the two clutch shafts on that side. The shafts have a very
coarse thread, the clutch pressure plates are sandwiched by nuts. Moving
the drive levers ultimately moves the clutch plates a few thousanths of an
inch, with most of the force magnification happening in the screw threads.
There is also a further speed reduction in the chain and sprocket linkage
from the clutches to the wheel axles.
This particular drive setup has no brakes - in new condition the clutches
are adjusted to drag equally in forward and reverse but unless everything is
working just right it's undependable, and at least I consider it safer to
set them all free - no brakes is better than having a mind of its own.
I read Wayne's reply that mentioned the problem obtaining or fabricating
real tracks. It's a far cry from dozer tracks but many outfits sell these
simple fabricated skid-steer tracks that may be a good start for a dozer
project.
They are just bent steel plate sections welded to heavy chain.
|
|
|
|
