I have two 'dead' tow mixers on my property at this point, both are victims of having the
rear end seize up- one from cement getting past the seal and into the gears from use with
papercrte, the other from the same scenario with paperadobe. I have a third mixer which is
still perfectly fine: it had a hole bored in the axle housing on the outside edge of the stock
tank and to that hole was welded a 3/4" diameter piece of pipe, about a foot tall so that oil
could be added and the standing oil column would be higher than the seal. The pipe is
threaded at the top side and a threaded cap is screwed on to keep the oil in and dust out.
Replacing the differential seal once in a while will help keep the seal from ultimately failing
when it wears out, so I've made sure to have that accessible from inside the tank. My first
mixer locked up once on probably the thirtieth or so load, the wheels suddenly stopped
turning. After draining the batch onto the ground and cleaning the thing out with a hose, I
noted that the seal had failed: there's a rubber bushing component which rests inside a
thin metal donut, and the rubber had been abraded away and sand had gotten down into
the gears of the differential, and a tooth (meaning one of the gears) had sheared off. I
took the whole thing apart, welded the tooth back on, ground it down, got a brand new
seal, repacked the differential and made many loads more blocks and then the same thing
happened again. This was with paper adobe, heavy on the adobe because I didn't mind the
extra weight and in fact wanted thermal mass and was excited by the fact that all my
materials were free and that dense paperadobe held nails and screws, performing in that
aspect as well as wood does, and it couldn't be shattered with a sledge hammer unlike a
block of concrete the same size- it would just dent. I figured it was wonder-material, plus
it didn't burn or even smolder. The paper-cement mixer was used for years by a local
commune before they finally finished their building projects and they sold their seized
mixer to a friend of mine who brought it to my property to try to make blocks. A note
about stock tanks leaking around the seal where the differential pokes through: cut a
piece of 3/4" plywood to sit under the tank and use some pan head screws to hold the
mixer onto the plywood: this will eliminate flexing of the bottom of the tank. Thin sheet
metal will flex without a rigid support beneath it. Plastic tanks may hold up better but
instead of flexing they'll tend to split/crack due to the bending forces and you'll end up
with cracks around the hole you've cut for the differential. You can cover the screw heads
(which will be inside your tank) with silicone to prevent them from leaking, and you can
also apply silicone to the gaps in the hole you've cut in the bottom of your tank where the
differential pokes through to help seal it. If you're concerned that the shearing forces
might shear the heads of the screws off you can be nutty like me and put a second sheet
of plywood inside the tank, and through-bolt the two pieces of plywood to one another,
effectively sandwiching the flimsy bottom of the tank between the two pieces of plywood.
--- In papercreters@yahoogroups.com, "daleandbren" <daleandbren@...> wrote:
>
> I am in the planning stages of building my first mixer. I hope to start
> building it very soon. My question, is there a make/model of
> axle/differential that works best. Chances of getting a freeby are
> better if it makes no difference. Thanks.
>
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