[PRCo] Re: Wheels__&__Shoes

[James B. Holland]

Fred Schneider wrote:

>Please allow me the privilege of punching holes in the theory that you can't mix shoes and wheels.
>And there is really no problem at Arden mixing the two.
>

             This is not debunking the problem but giving an example of 
how it works.     It  IS  a problem if you put up New Frogs intended for 
Wheels and try to operate shoes  --  It Did Happen in San Francisco as I 
mentioned below.     There is Most Definitely A Design Difference in the 
frogs with more overlap of  the guiding runners for  *Wheel--Frogs*  
than for frogs for shoes.     This overlap does not allow enough room 
for the shoe flange to pass thru  --  this is simple engineering and the 
difference is easily  *eyeballed*  when looking at the two frogs.



1.>--Put up New  Frogs__Designed--for--Shoes  --
            *Wheels*  will not have problems so it is extremely easy to 
mix the two.


2.>--Put up New  Frogs--Designed--for--Wheels  --
            *Shoes*  Will Have More Problems Than Not.



                 Not familiar with the particular location you mentioned 
at Arden  --  there are many items that affect tracking thru a frog.     
Angle of the turnout greatly affects tracking; spiral-easement turnouts 
greatly affect tracking; speed greatly affects tracking; car shift // 
leaning (ala PRCo B2B trucks on 1725--1799)  Greatly Affect Tracking; 
other problems greatly affect tracking.

                The more shallow the turnout the more problems in 
tracking and the slower the required speed  --  in spiral easements the 
car is still in the process of turning which interferes with the pole in 
trailing  --  on a standard radius turnout the car is completely into 
the turn and then the pole is trailed back toward the center of the car 
which greatly helps in choosing the right direction.     Speed thru ANY 
frog Greatly Increases the possibility of improper tracking and dewirement.

                 Dawn Jct. outbound on 42-Dormont was a shallow angle 
and prone to dewirement  --  Even Drake outbound at Washington Jct. was 
shallow angle and this contributed to dewirements here.

                Inbound north end of Smithfield St. bridge, right turn 
onto Fort Pitt after B&O demolishment is a spiral easement which gave 
potential problems  --  extremely slow speed needed here to keep pole 
tracking in the proper direction.     Same at West Portal in San 
Francisco  --  spiral easement outbound to L-line and extremely low 
speed needed to prevent pole from tracking onto wrong wire.

                 SHJ emerging from tunnel outbound is a shallow 
turnout.     Wire and frog aligned for primary direction of travel to 
35, 36, 37, 38, 39, 40, 42, 43  --  angle toward 44, 47, 48 lines could 
give a problem so frog was moved closer to the track frog which made it 
look like the pole was trailing toward the outside edge of the car on 
the turn but this greatly decreased the opportunity for dewirements and 
I never saw a dewirement there.

                 Many other similar locations but not going to detail 
them all.


             Those  High--Speed  properties which used Shoes used Solid 
Metal Shoes and greasing the overhead is mandatory  --  carbon insert 
shoes will not stand up to this high speed.     North Shore and Pacific 
Electric come to mind.


>"James B. Holland" wrote:
>
>  
>
>>Pittsburgh and Philly both used wheels.     Philly converted to shoes
>>about 1975--1980  --  Pgh. converted to pantographs from wheels.
>>
>>More to convert with large city  --  frogs are different.     With
>>wheel, only one point of wheel touches frog base whereas 3-4--inches of
>>shoe touches base.     More runner // guide overlap on the frog for
>>wheel which plays havoc with shoes.     They installed some wheel frogs
>>here in San Francisco in the latter 1970s and on a turn like the 42-wye
>>the pole would go straight thru.     Try to go straight thru at the same
>>type of location and the pole would make the turn.
>>
>>Am told that Philly didn't convert frogs when they changed and they
>>reportedly didn't have problems  --  but probably wasn't much left of
>>frogs at that time because of wear!
>>
>>rogertrolley.1 at juno.com wrote:
>>
>>    
>>
>>>It alway seemed to me a real mystery as to why PRC used wheels,when idustrywide most all companys used shoes so as to not wear out the overhead and to libricate it with carbon inserts. Johnstown used shoes and Pittsburgh didn't. Back in 1958 it seemed an achronism that it was that way,whereas you would think the big city would be far more modernistic than the small burg like Johnstown would have been !!!  cheers rogertrolley
>>>