Here is the Mercedes Euklid model 29,
with the casing removed.
I've done that to show you the mechanism.
To remove the casing you first take off
the two clearing handles,
and then the cover of the carriage
comes off with a few screws.
The cover on the right hand side of the casing comes off with a couple of screws.
Then the rear comes off by itself.
Remove this - again a few screws.
To take this part of the cover off
you do need to move the carriage shift button.
You can leave these button tops on here,
because you can tilt this, get this from underneath.
On this side you do have to remove
the division button top,
Again the side removes just by taking out four screws
And what you're left with is this bare calculator,
and inside you can now see the mechanism.
It has a set of 10 parallel toothed tracks,
and those are connected together on one lever.
On this side there's a piston that pulls that lever.
That lever is hinged so that it moves like that,
so the bottom rack moves out 9 units
and the top rack doesn't move at all.
So let's see that in action.
These columns of keys they control
these gears that are on an axle.
There are five little gears,
and each one rests between two racks.
The bottom one rests between rack eight and nine,
and if you press the 9 button it moves down
to engage with that rack,
but if you press the 8 button it moves up
to engage with rack number eight.
The same goes for the next gear for 6 and 7.
and this one is 4 and 5,
and 2 and 3,
The top gear, that is either engaged with rack 0 or with rack 1,
but if you press another button it rests in between.
So if I press a 6 so that gear is now
engaged with rack number 6,
and it now turns that axle as the racks go underneath it.
It turns it by 6 units, forwards and backwards,
and as the register only turns one way,
it just adds six,
and when the rack moves backwards is
when the carries are performed.
What happens when you subtract is that
the proportional racks move differently.
The lever they're connected to
is now pivoted at its other end,
so it moves out that way
and the top rack is going to be
the one that moves the furthest.
So let me show you that.
As you can see,
all these other columns where there's no keyboard,
there's still an axle with a little wheel at the top,
and those wheels are on rack zero
so that when you subtract
they actually are going to add 9, the complement of 0.
At the other end, here, is also an extra axle
that's connected up to this invisible digit as it were,
and that one also rotates,
and it actually causes a carry to be performed
so that an extra one is added to the register
because subtracting is first taking the complement,
the digit-wise complement of the number then adding 1.
So yeah, that's really all there is to it.
That's the proportional lever mechanism.
Thank you for watching.
