On 26 Apr, 22:13, "michael adams" wrote:
Instead of an escalator just imagine a large cable drum, where you
were walking on the hollow hub in the middle. The circumferance of
the outside edge of the drum which would represent the handrail
would probably be at least twice as long as the circumferance
of the hub which represented the tread. So your hands would probably
need to cover twice the distance of your feet. i.e they'd be
twice as busy.

Sorry, this is bonkers. The handrail is driven by a separate set of
drums so can run at any speed. Wikipedia has a good diagram:
http://en.wikipedia.org/wiki/Escalator

It's all in the gearing, which is presumably just incorrect at
Westminster.

U

michael adams wrote:

A better analogy may be two 3 metre diameter drums rotating on pivots
say 10 metres. apart. There's a large belt threaded around the outside
of the two drums, and a another belt threaded around two concentric
2 metre diameter drums attached to the larger drum. This makes the
circumferance of the large drum approx 9.3 metres and that of the
smaller drum approx 6.2 metres

Start off by drawing two vertical marks on the top two belts, say 1
metre from the left hand drum. Now rotate the left hand drum once
clockwise. The mark on the outside belt - the handrail will have
moved 9.3 m to the right
while that on the inner belt the - steps will have moved only 6.2 m.

I suspect this can all be explained quite clearly in two crisp
sentences by a competent engineer.

I'm not a competent engineer.... but how about

"You are talking rubbish. You are talking rubbish."

An escalator engineer was asked this question on TV. He said that when
escalators are new, there is no difference in speed. As components wear at
different rates, the speed difference appears.

In article .com, Mr
Thant writes
Sorry, this is bonkers. The handrail is driven by a separate set of
drums so can run at any speed.

I understood that the speed was made slightly greater so that people who
hold on to the handrail don't fall backwards. If it was slightly less
(and it's hard to make it *exactly* the same) people might unbalance
themselves before they realize what's happening - leaning forwards is
more obvious and easier to correct in time.

--
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Yes you are right and the earth is flat

--
John the West Ham fan


"Clive D. W. Feather" wrote in message
...
In article .com, Mr
Thant writes
Sorry, this is bonkers. The handrail is driven by a separate set of
drums so can run at any speed.

I understood that the speed was made slightly greater so that people who
hold on to the handrail don't fall backwards. If it was slightly less (and
it's hard to make it *exactly* the same) people might unbalance themselves
before they realize what's happening - leaning forwards is more obvious
and easier to correct in time.

--
Clive D.W. Feather | Home:
Tel: +44 20 8495 6138 (work) | Web: http://www.davros.org
Fax: +44 870 051 9937 | Work:
Please reply to the Reply-To address, which is:

Clive D. W. Feather wrote:
In article .com, Mr
Thant writes
Sorry, this is bonkers. The handrail is driven by a separate set of
drums so can run at any speed.

I understood that the speed was made slightly greater so that people
who hold on to the handrail don't fall backwards. If it was slightly
less (and it's hard to make it *exactly* the same) people might
unbalance themselves before they realize what's happening - leaning
forwards is more obvious and easier to correct in time.

But on a "down" escalator, falling forward is much more dangerous than
falling backwards.

On Sat, 28 Apr 2007 14:53:33 +0100, John Rowland wrote:

Sorry, this is bonkers. The handrail is driven by a separate set of
drums so can run at any speed.

I understood that the speed was made slightly greater so that people
who hold on to the handrail don't fall backwards. If it was slightly
less (and it's hard to make it *exactly* the same) people might
unbalance themselves before they realize what's happening - leaning
forwards is more obvious and easier to correct in time.

But on a "down" escalator, falling forward is much more dangerous than
falling backwards.

Let me guess, when an escalator is set to "down", the handrail instead
moves slightly slower than the steps?

"If you step onto the escalator at the bottom and keep holding the
rail, then by the time you reach the top your arm has been pulled
about 18 inches forwards relative to the rest of your body! "

Quick question - do you hang on all the way round the top curve (where
the escalator makes the transition from the incline to the flat - only
to the very top, not to where the handrail disappears back into the
gizzards of the machine*) ?

If the handrail were to travel at the same speed as the stepchain it
would lag behind severely on the top curve, as the radius of the curve
is larger than the radius of the stepchain. Hence it is possible that
the handrail is geared sufficiently so as to never go backwards
relative to the passenger, giving a "creep" on the incline that is
counteracted in the last few metres.

*footnote : the little bit of leather where the handrail did this on
older escalators used to be called an "elephant ear", 'cos that's what
it looked like ...