I could spend my spare time reading an improving book. Instead I find
myself wondering why do some escalators have the handrail running
slightly faster than the steps? I've noticed this on and off over the
years, and currently am most aware of it on the Jubilee line
escalators at Westminster. 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!

Assuming the same motor drives both the handrail and the steps, I
would have thought it takes some quite complex engineering to achieve
this feat. Why???

"peter" wrote in message
oups.com...

I could spend my spare time reading an improving book. Instead I find
myself wondering why do some escalators have the handrail running
slightly faster than the steps? I've noticed this on and off over the
years, and currently am most aware of it on the Jubilee line
escalators at Westminster. 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!

Assuming the same motor drives both the handrail and the steps, I
would have thought it takes some quite complex engineering to achieve
this feat. Why???


Presumably because the handrail follows a larger radius than the steps,
and thus has a larger circumferance, and so travels a greater distance
for each rotation of the motor.

michael adams

....

On Apr 26, 4:59 pm, "michael adams" wrote:
"peter" wrote in message

oups.com...

I could spend my spare time reading an improving book. Instead I find
myself wondering why do some escalators have the handrail running
slightly faster than the steps? I've noticed this on and off over the
years, and currently am most aware of it on the Jubilee line
escalators at Westminster. 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!

Assuming the same motor drives both the handrail and the steps, I
would have thought it takes some quite complex engineering to achieve
this feat. Why???

Presumably because the handrail follows a larger radius than the steps,
and thus has a larger circumferance, and so travels a greater distance
for each rotation of the motor.

michael adams



I can't see how that explains it; it should still stay level with the
same step surely? (If you you drew a line along the radius of a disc,
the line wouldn't split up as it rotated.)

It is a common phenomenon, although I thought it affected the older
escalators more.

There must just be different gearing between the motor and the
handrail, assuming it is the same motor.

"MIG" wrote in message
oups.com...
On Apr 26, 4:59 pm, "michael adams" wrote:
"peter" wrote in message

oups.com...

I could spend my spare time reading an improving book. Instead I find
myself wondering why do some escalators have the handrail running
slightly faster than the steps? I've noticed this on and off over the
years, and currently am most aware of it on the Jubilee line
escalators at Westminster. 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!

Assuming the same motor drives both the handrail and the steps, I
would have thought it takes some quite complex engineering to achieve
this feat. Why???

Presumably because the handrail follows a larger radius than the steps,
and thus has a larger circumferance, and so travels a greater distance
for each rotation of the motor.

michael adams



I can't see how that explains it; it should still stay level with the
same step surely?

(If you you drew a line along the radius of a disc,
the line wouldn't split up as it rotated.)



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.

If the sides of the drume was large enough you for you to just roll
along on the hub and stay in one place while hanging on when it
rolled upside down then you woudn't need to move at all. And the
same on the escalator.

But you don't. Both distances are flattened out and the distance
around the handrail - as on the drum is that much longer than that
on the tread.


michael adams

....




with




It is a common phenomenon, although I thought it affected the older
escalators more.

There must just be different gearing between the motor and the
handrail, assuming it is the same motor.

"MIG" wrote in message
oups.com...
On Apr 26, 4:59 pm, "michael adams" wrote:
"peter" wrote in message

oups.com...

I could spend my spare time reading an improving book. Instead I find
myself wondering why do some escalators have the handrail running
slightly faster than the steps? I've noticed this on and off over the
years, and currently am most aware of it on the Jubilee line
escalators at Westminster. 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!

Assuming the same motor drives both the handrail and the steps, I
would have thought it takes some quite complex engineering to achieve
this feat. Why???

Presumably because the handrail follows a larger radius than the steps,
and thus has a larger circumferance, and so travels a greater distance
for each rotation of the motor.

michael adams



I can't see how that explains it; it should still stay level with the
same step surely?

(If you you drew a line along the radius of a disc,
the line wouldn't split up as it rotated.)



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.

If the sides of the drume was large enough you for you to just roll
along on the hub and stay in one place while hanging on when it
rolled upside down then you woudn't need to move at all. And the
same on the escalator.

But you don't.

Er actually you do. The point is that on the escalator as on the
cable drum you can't remain vertical. If you keep your hands
in the same position on the rail you're gradually pulled out
of a vertical position. Although on an escaltor you have no choice
but to get off before you get the chance to turn upside down.



michael adams

....




with




It is a common phenomenon, although I thought it affected the older
escalators more.

There must just be different gearing between the motor and the
handrail, assuming it is the same motor.

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

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:

"michael adams" schrieb im Newsbeitrag
...

Assuming the same motor drives both the handrail and the steps, I
would have thought it takes some quite complex engineering to achieve
this feat. Why???

Presumably because the handrail follows a larger radius than the steps,
and thus has a larger circumferance, and so travels a greater distance
for each rotation of the motor.

That sounds logical. But why would the manufacture not use the exact radius
so that there is no difference in speed between handrail and steps. Why do
they use a slightly lager radius so that the handrail is a tiny bit faster,
never slower than the steps.

I experienced the same thing at different locations. And now I'm asking my
self if the load on the steps might be the problem. If there are a lot of
people standing on the escalator they might cause a little bit a slippage in
the transmission between steps and engine while the load on the handrail
keeps pretty much the same.
--
Matthias Wirtz - Karlsruhe, DE

"Matthias Wirtz" wrote in message
...
"michael adams" schrieb im Newsbeitrag
...

Assuming the same motor drives both the handrail and the steps, I
would have thought it takes some quite complex engineering to achieve
this feat. Why???

Presumably because the handrail follows a larger radius than the steps,
and thus has a larger circumferance, and so travels a greater distance
for each rotation of the motor.

That sounds logical. But why would the manufacture not use the exact
radius
so that there is no difference in speed between handrail and steps.

Why do they use a slightly lager radius so that the handrail is a tiny
bit faster, never slower than the steps.

....

Simply because the handrail is approximately 2½ feet further away from
the centre, because your hands are 2½ off the ground as compared with
your feet which are actually on the steps.


....

I experienced the same thing at different locations. And now I'm asking my
self if the load on the steps might be the problem. If there are a lot of
people standing on the escalator they might cause a little bit a slippage
in
the transmission between steps and engine while the load on the handrail
keeps pretty much the same.


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.



michael adams

....


--
Matthias Wirtz - Karlsruhe, DE

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.