Mark Goodge wrote:
On Sat, 14 Nov 2015 09:36:51 +0000, Clive D. W. Feather put finger to
keyboard and typed:

In message
-sept
ember.org, Recliner wrote:
I'm a little surprised that they claim it uses less power than a
conventional lift. If you have to raise a given mass through a
given vertical distance, shouldn't the answer be the same?

That assumes 100% efficiency in the mechanism. Not a safe assumption.

Yes, I agree about the *energy* consumption. But perhaps it gets away with
a less powerful motor, as it's slower than a normal lift.

In addition, the fact it's sliding down rails rather than hanging in
free space may alter the efficiency of the mechanism.

Yes. A simple thought experiment works here. It clearly requires less
energy to push a wheeled object horizontally than it does to lift it
vertically. So there's clearly also a continuum between 0 degrees = least
energy and 90 degrees (from the horizontal) = most energy, and therefore
something like 45 degrees = somewhere in between the two.

If you ignore friction, it takes zero net energy to move an object at a
fixed speed horizontally, and a fixed amount to lift it a particular
distance. But the *power* will be less if you lift it more slowly, which
the inclined lift does, compared to a typical vertical lift. Of course,
friction isn't zero, and will be more, the shallower the angle. But if the
lift box runs on wheels on rails, the friction will be low.