[PRCo] Re: Fwd: Re: Double--Point__RR__Turnouts-__-1940--1950

[Fred Schneider]

Go look at some of the special work in West Philly, Bob.   Some of it  
is pretty badly worn.   Of course those are manganese steel castings  
instead of carbon steel so that they wear longer than the rails.    
But they still don't wear forever.  In some cases railways fixed the  
wear with welds.

But if it didn't ride on the flange, it would bump across the gap in  
the rail.    By riding on the flange, the ride is smooth.   There  
were exceptions.   Route 21 FINEVIEW at Charles St. and Perrysville  
Avenue - the tongue remained moveable for car house movements but the  
flangeway through the frog was welded shut to make the ride smooth  
(or perhaps they had been having problems with derailments and were  
correcting it that way).   So any cars returning to the barn had to  
crash up over the weld and back down.   (Amazing the weird things I  
can remember ... but I have trouble remembering my anniversary.   
Remembering some of these crazy things comes from not owning an  
automobile until I was 21.   I did a whole lot of walking ... up to  
20 miles during many days ... you can observe a lot that way.)

fws

On Dec 14, 2006, at 10:17 AM, Bob Dietrich wrote:

> Fred and Jim, your explanations are very good, but hey raise a  
> question in
> my mind.  You both say that the right wheel must ride on the flange  
> in the
> flangeway.  I was under the impression that the tread spanned the gap
> between the rail and the point, much like a standard railroad  
> frog.  If the
> flange rode on the casting it would quickly wear a grove in the  
> casting and
> cause some nasty bumping and deterioration.
>
> Am I misinformed on this?  Is the flange-way plus the width of the  
> point in
> the right-wheel casting really wider than the wheel tread?  I know  
> models
> span that gap but model wheels tend to be wider than prototype -  
> but then so
> do clearances.
>
> Bob
>
> -----Original Message-----
> From: pittsburgh-railways-bounce at lists.dementia.org
> [mailto:pittsburgh-railways-bounce at lists.dementia.org] On Behalf Of  
> Fred
> Schneider
> Sent: Wednesday, December 13, 2006 8:42 PM
> To: pittsburgh-railways at dementia.org; McGuire Mark
> Subject: [PRCo] Fwd: Re: Double--Point__RR__Turnouts-__-1940--1950
>
> Mark and any one else who wants the long explanation:
> I'm not sure if you got the gist of the single point switch versus
> double point switch from the model builder's diagrams but these two
> pictures are great explanations.
>
> The first two URLs show double point switches ... both points move
> back and forth like a railroad switch.   Go out and look at any CSX
> or FEC switch in Jacksonville and you will understand the concept.
> Wheels rolling over it are always solidly guided on a steel point and
> the outside rail no matter which way it is set, left or right. (or
> left, right or center in the case of a three-way switch.)     The key
> to understanding here is that with a double point switch, the tread
> side of the both left and right wheels (and tread side of their
> flanges) always rides on the point or a fixed rail.  You will also
> notice, on the outside rail adjacent to the frog in each switch,
> guard rails, that prevent the wheel from following the wrong rail at
> the frog and derailing.
>
> Now look at the Drake picture -- the third URL -  there is only one
> moveable point and that is built into the casting on the left rail.
> The point can move left or right.   At the present time in is moved
> to right and it will lead the car around the curve to the left.   The
> backside of the wheel will be forced by the tongue to roll to the
> left.   If the switch point is moved to the left, then it will force
> the front side of the flange to ride on to the point and the car will
> go to the right.   Note that the entire wheel may or may not ride on
> the point depending on which way it is thrown.       The small box
> near the hinge just contains a spring (in case) so that once thrown
> in will stay in that position.   The common position for the Drake
> switch was the other way from the way shown was the loop was finished
> and in service.
>
> Now look at the casting to the right in the Drake loop picture ...
> the casting opposite to the frog ...  it has no moveable point .   It
> doesn't need one because the single point on the other side will
> force a car to go either way.   All it needs to do is support the
> weight of the car.   And because there cannot be a running rail where
> the car diverges, the car rides on wheel flanges.
>
> Now where are the guard rails opposite the crossing frog in the Drake
> loop?   Ah, you don't need them because girder rail is used and the
> entire rail has a built-in flange along the inside.
>
> If you study railroad switches, you will also see some self-guarded
> frogs with lips build onto the edge of the frog castings for use in
> industrial sidings but I know of no instances where they were used in
> high speed turnouts.
>
> The single-point switches were quite adaptable to low speed city
> street operation.   They worked well at 5 to 10 mph.   But a high
> speeds cars tend to derail.   And that is which I noted that the
> European systems often use double-point switches in city streets and
> they tend to run like hell.   And they do it with safety.
>
> If the explanation isn't clear, please come back at me.
>
> Fred Schneider
>> .
>> .
>> http://lists.dementia.org/files/pittsburgh-railways/RR%20Double%
>> 20Point%20Turnout%20096.jpg
>>
>> .
>> http://lists.dementia.org/files/pittsburgh-railways/03-Tylerdale%
>> 200096%20195xxxxx%20RSchramm.jpg
>> .
>> http://lists.dementia.org/files/pittsburgh-railways/03-Track%20Drake
>> %20Loop%20Construct%201953xxxx%2001.jpg
>>
>>
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