Re: Scale for weighing fully laden power wheelchairs

[Steve Uhrig <Steve@xxxxxxxxxx>]

On Mon, 22 Aug 2005 04:29:55 -0400, "Robert Green"
<ROBERT_GREEN1963@xxxxxxxxx> wrote:

> My question is this:  If I took four identical bathroom scales, a 4x4  sheet
> or two of 3/4" plywood and attached wood block "feet" at each corner that
> would sit on the bathrooms scales, would their readings (assuming each scale
> was zeroed out to start) total up to the weight of the object?

Think of this:

If you had TWO scales, and a board bridging them, and put a known
weight on them, would each scale weigh half the tare (weight minus
board) weight?

I think you have to add these algebraically, not directly. Each scale
is seeing more than the 1/4 load.

Simple enough to test the concept. Weigh something like concrete
blocks, or a stack of phone books, on several scales and take an
average so you have a 'standard'.

Then set up your 4 scales and see what you get.

Or take two scales, weigh yourself, then straddle both and see what
you see.

I am an electric wheelchair user, and the specs for anything in the
last 20 years are available on the web. That might save you the
effort. There may be some minor differences due to accessories like
baskets, cane or oxygen bottle holder, etc. but all well within your
tolerance requirement.

As wheelchairs must all be approved by some or another letter agency,
you may be able to find a database with all needed info in one place.

Don't forget dead batts will weigh 5-10 pounds less than good ones.
And some have chargers onboard which may be missing, so look for that
and consider the weight.

Tires are high wear items and generally are replaced as standard every
year. Batts may last a year or two, rarely longer, depending on how
they're used. Brake linings need replacement periodically. Bearings
need lubrication esp if the thing is used outside or they will need
periodic replacement.

Each manufacturer will have a maintenance schedule for his chair, and
a service manual. You'll start seeing more than one of the same type
as there are models distinctly popular and unpopular. Manuals may be
worth the expense.

Good luck with your project ... Steve

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Steve Uhrig, SWS Security, Maryland (USA)
Mfrs of electronic surveillance equip
mailto:Steve@xxxxxxxxxx  website http://www.swssec.com
tel +1+410-879-4035, fax +1+410-836-1190
"In God we trust, all others we monitor"
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