The stuck trolleybus

[Mark Brader]

As I said in another thread just recently,

This
Loading Image...
is a trolleybus, known in some cities as a trolley coach, trackless
trolley, trackless tram, electric trolley bus, and other such
variations. It is powered from the two overhead wires through two
poles, which are spring-loaded to press upward against the wires.
Early trolleybuses had a grooved wheel at the top of each pole; this
one uses a sliding shoe. Either way, it makes continuous electrical
contact with the wire as the trolleybus runs along its route.
The poles have some room to swing to one side or the other, so on a
street that's four lanes wide, trolleybuses can use either the left
or the right lane. But if the driver steers too far from the wires,
one or both poles will come off and leave the vehicle powerless.
Some trolleybuses today are designed to be driven away from the wires
in some situations. Either they have a diesel engine that's turned
on for the purpose, or they have batteries that can store enough
electricity to drive the necessary distance. But both of these
options add weight and cost, so the traditional trolleybus that
requires continuous contact with the wires is also still used.
And that's the sort we had in Toronto (where the photo was taken)
until the early 1990s when the TTC decided to stop using trolleybuses
altogether.

In that thread, I also noted that from time to time it happens that
the poles accidentally come off the wires. Most often this happens
at intersections where trolleybus routes branch or cross each other:

Loading Image...

The driver goes too fast or fails to steer accurately enough or
the switch in the overhead wires sends the poles the wrong way.
(Yes, there is a switch in the wires, with moving parts, much like
a railway track switch mountted upside-down. Traditionally it's
controlled by a sensor that detects, at a particular position,
whether the approaching trolleybus is drawing power or not.)

Anyway, as I said before, usually it's no big deal if the poles
come off. They aren't likely to damage each other or anything else;
typically the driver just gets out, walks behind the trolleybus,
and pulls on the ropes to set the poles back on the wires. Only
if the driver took a wrong turn or something and the poles weren't
within reach of the wires would there be a need to call for help.


It did see it happen once that a trolleybus needed rescuing because
of a wrong turn. At that time all buses and trolleybuses serving
Eglinton subway station used these platforms:

Loading Image...

All of them are parallel, but not all of them had trolleybus wiring,
and the driver had picked the wrong one to drive into.

The truck that came to help was the same one that would be used if
the overhead wires were damaged, with a platform on top so that
someone could stand on it to repair them.


But here, finally, is the puzzle. Once I saw a different reason for
help to be needed. As far as I could tell:

* The trolleybus was in good working order
* In particular, the poles, the ropes, and so on were all undamaged
* The overhead wires were also in good working order and undamaged
* The trolleybus was on its normal path
* The power supply was working normally

But in this case it was *not* possible to simply use the ropes to put
the poles back on the wires and drive on, and the rescue truck was
required on this occasion too.

Why was it required? What had happened?

[Gene Wirchenko]

On Mon, 21 Dec 2015 01:10:13 -0600, ***@vex.net (Mark Brader) wrote:

[snip]

Post by Mark Brader
But here, finally, is the puzzle. Once I saw a different reason for
* The trolleybus was in good working order
* In particular, the poles, the ropes, and so on were all undamaged
* The overhead wires were also in good working order and undamaged
* The trolleybus was on its normal path
* The power supply was working normally
But in this case it was *not* possible to simply use the ropes to put
the poles back on the wires and drive on, and the rescue truck was
required on this occasion too.
Why was it required? What had happened?

Did a tree or something similar block the way? The bus can not
back up.

Sincerely,

Gene Wirchenko

[Mark Brader]

Post by Gene Wirchenko

Post by Mark Brader
But here, finally, is the puzzle. Once I saw a different reason for
* The trolleybus was in good working order
* In particular, the poles, the ropes, and so on were all undamaged
* The overhead wires were also in good working order and undamaged
* The trolleybus was on its normal path
* The power supply was working normally
But in this case it was *not* possible to simply use the ropes to put
the poles back on the wires and drive on, and the rescue truck was
required on this occasion too.
Why was it required? What had happened?

Did a tree or something similar block the way?

Good idea, but not what happened. The route ahead was clear.

Post by Gene Wirchenko
The bus can not back up.

I've never seen it done, but I would think that trolleybuses would in
fact have the ability to reverse. Because the angle of the poles would
be wrong, they'd have to go very slowly, but it could be useful in the
garage where lines of them are parked very close. But reversing would
be no use if the road was blocked, unless there was another route with
wires that they could switch onto. So Gene's guess is perfectly valid,
just wrong.

[Mark Brader]

Post by Mark Brader
As I said in another thread just recently,

This
http://transit.toronto.on.ca/images/trolleybus-9106-03.jpg
is a trolleybus, known in some cities as a trolley coach, trackless
trolley, trackless tram, electric trolley bus, and other such
variations. It is powered from the two overhead wires through two
poles, which are spring-loaded to press upward against the wires.
Early trolleybuses had a grooved wheel at the top of each pole; this
one uses a sliding shoe. Either way, it makes continuous electrical
contact with the wire as the trolleybus runs along its route.
The poles have some room to swing to one side or the other, so on a
street that's four lanes wide, trolleybuses can use either the left
or the right lane. But if the driver steers too far from the wires,
one or both poles will come off and leave the vehicle powerless.
Some trolleybuses today are designed to be driven away from the wires
in some situations. Either they have a diesel engine that's turned
on for the purpose, or they have batteries that can store enough
electricity to drive the necessary distance. But both of these
options add weight and cost, so the traditional trolleybus that
requires continuous contact with the wires is also still used.
And that's the sort we had in Toronto (where the photo was taken)
until the early 1990s when the TTC decided to stop using trolleybuses
altogether.

In that thread, I also noted that from time to time it happens that
the poles accidentally come off the wires. Most often this happens
http://transit.toronto.on.ca/images/trolleybus-9102-01.jpg
The driver goes too fast or fails to steer accurately enough or
the switch in the overhead wires sends the poles the wrong way.
(Yes, there is a switch in the wires, with moving parts, much like
a railway track switch mountted upside-down. Traditionally it's
controlled by a sensor that detects, at a particular position,
whether the approaching trolleybus is drawing power or not.)
Anyway, as I said before, usually it's no big deal if the poles
come off. They aren't likely to damage each other or anything else;
typically the driver just gets out, walks behind the trolleybus,
and pulls on the ropes to set the poles back on the wires. Only
if the driver took a wrong turn or something and the poles weren't
within reach of the wires would there be a need to call for help.
It did see it happen once that a trolleybus needed rescuing because
of a wrong turn. At that time all buses and trolleybuses serving
http://transit.toronto.on.ca/bus/routes/images/097-yonge-01.jpg
All of them are parallel, but not all of them had trolleybus wiring,
and the driver had picked the wrong one to drive into.
The truck that came to help was the same one that would be used if
the overhead wires were damaged, with a platform on top so that
someone could stand on it to repair them.
But here, finally, is the puzzle. Once I saw a different reason for
* The trolleybus was in good working order
* In particular, the poles, the ropes, and so on were all undamaged
* The overhead wires were also in good working order and undamaged
* The trolleybus was on its normal path
* The power supply was working normally
But in this case it was *not* possible to simply use the ropes to put
the poles back on the wires and drive on, and the rescue truck was
required on this occasion too.
Why was it required? What had happened?

Okay, a hint. As with the other puzzle, this incident did not happen on
level ground. It was nearly level, but the slight incline was critical.

[Alexander Thesoso]

Post by Mark Brader
Okay, a hint. As with the other puzzle, this incident did not happen on
level ground. It was nearly level, but the slight incline was critical.

One (or both) pick-ups bounced off of the wire, just past a crossing
support wire. The bus rolled back and the mast slid up, over the
crossing support wire. The tip was held up, it its highest position,
between the power wires, resting on the crossing support wire. It
couldn't be moved in any direction.

[Mark Brader]

Post by Alexander Thesoso

Post by Mark Brader

Post by Mark Brader
As I said in another thread just recently,

This
http://transit.toronto.on.ca/images/trolleybus-9106-03.jpg
is a trolleybus, known in some cities as a trolley coach, trackless
trolley, trackless tram, electric trolley bus, and other such
variations. It is powered from the two overhead wires through two
poles, which are spring-loaded to press upward against the wires.
Early trolleybuses had a grooved wheel at the top of each pole; this
one uses a sliding shoe. Either way, it makes continuous electrical
contact with the wire as the trolleybus runs along its route.
The poles have some room to swing to one side or the other, so on a
street that's four lanes wide, trolleybuses can use either the left
or the right lane. But if the driver steers too far from the wires,
one or both poles will come off and leave the vehicle powerless.
Some trolleybuses today are designed to be driven away from the wires
in some situations. Either they have a diesel engine that's turned
on for the purpose, or they have batteries that can store enough
electricity to drive the necessary distance. But both of these
options add weight and cost, so the traditional trolleybus that
requires continuous contact with the wires is also still used.
And that's the sort we had in Toronto (where the photo was taken)
until the early 1990s when the TTC decided to stop using trolleybuses
altogether.

In that thread, I also noted that from time to time it happens that
the poles accidentally come off the wires. Most often this happens
http://transit.toronto.on.ca/images/trolleybus-9102-01.jpg
The driver goes too fast or fails to steer accurately enough or
the switch in the overhead wires sends the poles the wrong way.
(Yes, there is a switch in the wires, with moving parts, much like
a railway track switch mountted upside-down. Traditionally it's
controlled by a sensor that detects, at a particular position,
whether the approaching trolleybus is drawing power or not.)
Anyway, as I said before, usually it's no big deal if the poles
come off. They aren't likely to damage each other or anything else;
typically the driver just gets out, walks behind the trolleybus,
and pulls on the ropes to set the poles back on the wires. Only
if the driver took a wrong turn or something and the poles weren't
within reach of the wires would there be a need to call for help.
It did see it happen once that a trolleybus needed rescuing because
of a wrong turn. At that time all buses and trolleybuses serving
http://transit.toronto.on.ca/bus/routes/images/097-yonge-01.jpg
All of them are parallel, but not all of them had trolleybus wiring,
and the driver had picked the wrong one to drive into.
The truck that came to help was the same one that would be used if
the overhead wires were damaged, with a platform on top so that
someone could stand on it to repair them.
But here, finally, is the puzzle. Once I saw a different reason for
* The trolleybus was in good working order
* In particular, the poles, the ropes, and so on were all undamaged
* The overhead wires were also in good working order and undamaged
* The trolleybus was on its normal path
* The power supply was working normally
But in this case it was *not* possible to simply use the ropes to put
the poles back on the wires and drive on, and the rescue truck was
required on this occasion too.
Why was it required? What had happened?

Okay, a hint. As with the other puzzle, this incident did not happen on
level ground. It was nearly level, but the slight incline was critical.

One (or both) pick-ups bounced off of the wire, just past a crossing
support wire. The bus rolled back and the mast slid up, over the
crossing support wire. The tip was held up, it its highest position,
between the power wires, resting on the crossing support wire. It
couldn't be moved in any direction.

Close enough! Support wires weren't actually involved: it was one
trolleybus line (pair of power wires) crossing another, and the pole
went up the center of the diamond. Specifically, it was at the
entrance to Eglinton station (see the above photo), where westbound
trolleybuses on Eglinton Av. turned across the eastbound wires to get
into the station.

The driver must have been going quite slowly, and then failed to
brake when the trolleybus started rolling back. As I recall, the
rescue crew actually took the diamond apart to get the pole out --
presumably this was easier than removing the pole from the roof of
the trolleybus.


Merry Christmas, all.
--
Mark Brader, Toronto | "...and if sooner or later your revels must be ended,
***@vex.net | well, at least you reveled." --Roger Ebert

My text in this article is in the public domain.