There needs to be a Merchandise:Stocking subcategory.
A local department store recently did an expansion, and somehow the
results, as perceived by various customers AND employees, was
unsatisfactory. Management wanted to stock a great many new items, but
the new store wasn't quite big enough
to hold them all. As a result, quite a
few items previously stocked, before the expansion, are no longer available in
that store. Which is why various customers and employees became upset.
From outside the building it is obvious that they actually expanded it just
about as much as could possibly fit in the surrounding terrain, and still have
an adequate parking lot for cars. Well, despite the limited floor area inside, it
happens that the ceiling of this store is quite high, perhaps as much as 10
Suppose there was a way to make the shelves reach near-to the ceiling, yet
also were easily accessed by the customers? I've seen some big hardware
stores make a compromise along those lines, with fixed shelving built quite
high, and forklifts actually are driven around the store aisles, during business
hours, to get stuff down from high places when needed.
Those hardware stores also tend to have a special way of stocking certain
types of items, such as rolls of carpeting or spools of wire or cable. Imagine
a heavy-duty motorcycle-type chain going around 4 sprockets in a tall
rectangle. Now imagine two of them, with a number of axles stretching
across the distance between them, attached to the chains (not the
sprockets). Carpet rolls or wire spools are threaded onto those axles.
A motor drives the chains and attached axles in a big rectangular loop, up
toward the ceiling, then perhaps a meter away from the ailse, then back down
toward the floor, then back toward the aisle. The motor is keyed so that only
a store employee can run it (for safety reasons). But any item anwhere in the
loop is easily accessible.
A Shelvator will extend that idea, so that shelves will travel the loop, and stay
horzontal the whole way around it (I'll get back to this in a bit). Now the store
will have lots more shelf-space on which to stock stuff, and all the shelves are
theoretically in potentially-easy reach of the customer.
The hardware stores I've seen have their moving-axle gadgets surrounded by
other normal/fixed shelving units, so that only one side of the unit is
accessible. A Shevator should have both primary sides accessible. That is,
if in your aisle you see the Shelvator shelves going up, someone in the next
aisle, looking at it, will see the shelves going down. The drive motor, of
course, should be able to run in either direction.
Now, if the store is full of customers, there won't be enough employees to run
a store full of Shelvators, so a way must be found to let the customers safely
operate them. I think the way to do it is to put sliding glass doors in front of
each Shelvator. The doors are connected to a safety interlock, so the
Shelvator motor can only be turned on when the doors are closed (yes, in
People can certainly look through the glass to see what is on the moving
shelves, and of course sliding a glass door open (in either aisle) automatically
makes the Shelvator stop.
OK, now about keeping those shelves horizontal. This is more difficult to do
than one might at first glance think, and I suspect that's why I've never seen a
Shevator anywhere that I recall. For example, if you simply suspend a shelf
from the moving axle, any imbalance on it can cause items on the shelf to
spill. And two moving axles, supporting one shelf, are geometrically
impossible (their paths collide).
Nevertheless, I think I have a solution for this geometry problem, for which
pure text is inadequate to describe. I'll have to link a sketch some time.
=========Added Jan 16, 2012=========
An image has now been posted (linked). The single image has two sketches
in it. The larger upper sketch is an overall side view (shopping aisles would
be at left and right of it). 4 sort-of random shelves (gray) are included.
In that sketch, the Red lines represents the 2 chains (one in foreground and
one in background, overlapping in this sketch) that carries axles around the
rectangular loop, as previously described. The 4 black circles represent 8
chain sprockets (again, 4 in foreground and 4 in background).
The vertical black line in the center represents the "back wall" that shoppers
will see, as they stand to the left or to the right of this sketch, and look at the
The lower sketch is an enlargement of a single shelf (side view). It has a
central/upper axle (attached to the chains as described above), and 4 wheels,
two in the foreground and 2 in the background. (In the following text I will
pretend there are just the 2 foreground wheels, for clarity.) The dotted Red
lines in this sketch are the hypotenuses of two rignt-angle triangle (not all
drawn). The Blue lines in both sketches represent guides for the wheels.
If the shelf tries to tilt, it can't because a wheel will press up against one of
the blue guides. The guides become complicated at the top of the Shelvator.
There are gaps for the support-axles to pass through them, and for "inner"
shelf wheels to also pass through them. Meanwhile, a completely-enclosed
guide path, for the "outer" shelf wheels, is used to ensure that the shelf still
(Well, a tiny tilt will be possible, because the wheel can't simultaneously roll
along two enclosing guides; there needs to be, say, a 1-millimeter gap
between the wheel and one guide.)
Note how the uppermost shelf in that upper sketch stretches across the large
gaps in the guides. So, at all times at least one wheel is fully enclosed by a
guide, or the pair of wheels are appropriately adjacent to two guides.
At the bottom of the unit, because the central guides can't go all the way
down, there is reason to also have some fully-enclosing guides. The effect of
having those hypotenuses ensures that between the mounting point for the
chain-axle, and the mounting point for either wheel, each shelf must remain
In terms of positions of some of this stuff along the Z-axis (not portrayed in
the sketches), let's imagine facing a Shelvator the way a shopper would. The
shelves are in plain sight behind the sliding glass doors; the whole thing is
inside a sort of "casing" --allowing the chains and sprockets and wheels and
guides and drive-motor to be hidden from view. (Well, the drive-motor might
best be located at the very top of the unit, above everything, where it can have
a long axle to engage the chains with additional sprockets.)
Inside the casing, at far-left and far-right, are the chain loops. The guides,
and the wheels they affect, are positioned not-quite-as-far to the left and to
the right, which prevents any conflict between the shelf-wheels and the main
drive chains. And, as previously mentioned, there are gaps in the guides to
allow the support-axles to pass through them, so again conflict is prevented,
even as the guides suffice to force the shelves to stay basically level.
The rest of the space, in-between the wheels and guides, as the shopper
looks, is the shelf-space (behind which is that in-the-middle "back" wall,
which is directly attached to the sides of the overall Shelvator casing). Like
that linked AutoPantry, it may be appropriate to have some end-pieces for the
shelves, to keep merchandise (and hands!) away from the dirty chains.