[PRCo] Re: B2 and B3 Trucks

[James B. Holland]

Boris Cefer wrote:

>Correction of the correction: Jim had written B2!!! Guess he was comparing
>the spring equalization of the B-2 with the frame equalization of a truck
>that would contain rubber bushings in all 4 sideframe clamps.
>

And Jim also stated that the B3 had two flexible joints at opposite 
corners and 2-rigid mountings of axle to sideframe.

>Speaking of trucks, when I saw the remaining Pittsburgh PCCs equipped with
>B-3 trucks, I noticed that PAAC added SOMETHING (rectangular plates) to the
>rubber blocks which restrain bolster movements, but I was not able to
>recognize what that SOMETHING was, because it was painted. My opinion is
>that this improvement intended to provide protection of the rubber blocks
>against direct contact with the bolster to avoid wear of the rubber surface
>and it was possibly a steel or fibre plate screwened to the rubber.
>On 1711 at PTM I also noticed that its original SLCCo truck (the front one)
>had the rubber block pockets like worn by an excessive lateral movements of
>the bolster against the sideframes. That would indicate that the rubber
>blocks had not been maintained in adequate condition and the bolster was
>allowed to move from one emergency stop to the other without any dampening
>by the friction between the rubber and bolster (even small amount of
>friction because the rubber blocks should not be inserted in their pockets
>with large pressure).
>
>Boris
>
>----- Original Message -----
>From: "Fred Schneider" <fschnei at supernet.com>
>To: <pittsburgh-railways at dementia.org>
>Sent: Friday, January 28, 2005 3:39 AM
>Subject: [PRCo] Re: B2 and B3 Trucks
>
>
>  
>
>>Correction:  The B3 truck frame can only bend at two corners but that is
>>    
>>
>all
>  
>
>>that is needed to allow flexibility at four corners.  (see Jim's statement
>>    
>>
>that
>  
>
>>is now in a larger font, below)  Take your thumb and forefinger of each
>>    
>>
>hand
>  
>
>>and touch them thumb to thumb, forefinger to forefinger to simulate the
>>    
>>
>box
>  
>
>>shape of the frame.   Now notice how you can move them so that you can
>>    
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>lift any
>  
>
>>one of the four corners independent of the other three. Lifting a wheel at
>>    
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>the
>  
>
>>fix corner flexes the rubber in two non-fixed corners.   Functionally it
>>    
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>is the
>  
>
>>same as the B2.  It allows each wheel to apply equal weight to the rail no
>>matter which corner is higher.   the B3 had frame equalization, i.e. the
>>    
>>
>frame
>  
>
>>was allowed to flex.    It wasn't totally common but there are other
>>    
>>
>designs
>  
>
>>out there that did the same thing, such as the St. Louis EIB series
>>    
>>
>(you'll
>  
>
>>find them on a lot of the older Johnstown cars).
>>Spring equalization, however, was much more common.  Meaning springs were
>>    
>>
>used
>  
>
>>to transmit equal weight on the rail at each wheel  It just takes a lot
>>    
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>more
>  
>
>>parts to do the same thing
>>
>>I wish I had all of the comments that went back and forth between the
>>    
>>
>engineers
>  
>
>>during the ERPCC and TRC truck design phases.  I suspect that for both the
>>    
>>
>B1,
>  
>
>>B2, B2b and B3 designs, minimum weight remained a very important
>>consideration.  When Philly Suburban asked for a MCB type truck for their
>>    
>>
>1949
>  
>
>>St. Louis cars, they got a PCC style body with a fabulous ride not matter
>>    
>>
>how
>  
>
>>rough the track was.  But it had solid steel wheels and a solid steel
>>    
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>frame ...
>  
>
>>there wasn't an ounce of rubber to keep the high frequency noises from
>>penetrating the car body.  Noise suppression was not as important on an
>>interurban railway as it was on city streets.  It was a much heavier
>>    
>>
>design.
>  
>
>>Boris's statement about the movements a truck dampened was very good.  The
>>    
>>
>B2
>  
>
>>bolster hangs on four swing links.  If centrifugal force tries to push the
>>    
>>
>body
>  
>
>>to the outside of a curve, it is lifted up on the swing links and
>>    
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>immediately
>  
>
>>falls back down to center.  Just picture a beam hung on rods at each end
>>    
>>
>that
>  
>
>>can rotate about an axis.   On the B3 the bolster simply moves sideways
>>    
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>against
>  
>
>>rubber blocks.
>>
>>The B2 designs were not all alike.  The earliest cars had rubber springs
>>vulcanized to steel coil springs, eight to a car, two at each end of each
>>axle.  The were simply following on a practice done for years .. that one
>>    
>>
>type
>  
>
>>of spring has different properties than another.  For years the industry
>>    
>>
>used
>  
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>>eliptic springs above coil springs for the same reason.  When World War II
>>    
>>
>came
>  
>
>>along, with the attendant rubber shortages, the few new cars came through
>>    
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>with
>  
>
>>steel coil springs.  Come to the Baltimore Streetcar Museum some day when
>>    
>>
>I'm
>  
>
>>there and I'll show you just how rought steel coils alone can be.  When I
>>    
>>
>was
>  
>
>>doing the PCC book I came across all sorts of spring drawings for a B2
>>    
>>
>truck.
>  
>
>>I surmised that this was one of those cases where "Its your car.  You're
>>    
>>
>paying
>  
>
>>for it.  You can have whatever you want."   The same thing resulted in a
>>ghastly number of different control versions, mostly just differences in
>>resistance development.  An engineer from GE told me that there was no
>>    
>>
>valid
>  
>
>>reason for all the differences except that GE was in business to make
>>    
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>money and
>  
>
>>they would make whatever the customer wanted.   Westinghouse wasn't dumb
>>either.
>>
>>Remember two that one of the most important things the ERPCC was trying to
>>    
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>do
>  
>
>>in 1930-1935 was to reduce noise (audible vibrations) as well as rough
>>    
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>riding.
>  
>
>>They were trying to copy an automobile.  The B1 and B2 trucks gave the
>>    
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>quiet
>  
>
>>cushioned ride they wanted.  The B3 came about because of a need for a
>>    
>>
>truck
>  
>
>>that could ride acceptablly well on Pittsburgh's rough unpaved tracks.  It
>>should come as no surprise that PRC was behind the B3 because they had
>>    
>>
>more
>  
>
>>miles of private right-of-way than any city of that size or larger.  And
>>therefore the needs were different.
>>
>>For the model builders out there who question why we must equalize a truck
>>    
>>
>...
>  
>
>>it isn't done in small models such as HO and N gauge because we solve the
>>problem of uneven track with gigantic flanges.   And model builders need
>>    
>>
>not
>  
>
>>worry about comfort to the little people in their cars, nor to problems
>>    
>>
>with
>  
>
>>momentary loss of traction to one axle.
>>
>>I'm thinking through my fingers when I say that there might also have been
>>fewer problems with the B2 had American's not staggered rail joints.  Had
>>    
>>
>we
>  
>
>>put all the rail joints opposite each other like the British do, there
>>    
>>
>would
>  
>
>>have been a lot of bounce on rough track but not a lot of sway.
>>
>>"James B. Holland" wrote:
>>
>>    
>>
>>>All the  *problems*  with B3s are lateral and that is where the B2
>>>excels.       And I believe a case can be made for the B2 being better
>>>on rail joints as well since the framing of the B2 allows flexing at All
>>>4-corners of the truck, Not Just 2.       Vertical shocks have more room
>>>for absorption in a B2 and less is transmitted to the bolster and car
>>>      
>>>
>body.
>  
>
>>>Going to a system like Shaker is where one can experience an absolutely
>>>exquisite ride on B2 trucks at Break Neck Speeds.       Have done that
>>>often.       The Operators Did Not Like the B3-equipped IT cars because
>>>they bounced considerably  --  never had the opportunity to ride them on
>>>Shaker but I Did Try!       But I shall dismiss the problem bouncing to
>>>age and very low maintenance of the springs and spring pots over time
>>>--  the cars were only for extra usage to fill schedules.       Had they
>>>been brought up to standards of other Shaker equipment, the ride may
>>>have been much better and without bounce.
>>>
>>>Boston is also an excellent example of using B2s on prw at High
>>>Speeds.       From an engineering perspective the B3 may be better on
>>>prw but from the perspective of the rider, I think the B2 would be Just
>>>As Good and Possibly Better than the B3.
>>>
>>>The B3 being stiffer makes the ride harder  --  but don't get me wrong,
>>>I Favor the B3.
>>>
>>>The  BIG  area where B2 fails is that motor vibration is transmitted to
>>>the car body because the motors use the same springs for shock
>>>absorption that supports the body.       Riding a B2 at speed on PRCo
>>>was quite an experience with body panels and windows and all else
>>>rattling to beat a band and on prw the value of the B2 is masked by the
>>>motor vibration problems.       But otherwise I found the Actual Ride
>>>Very Acceptable on B2s on prw  --  we had quite a bit of prw on city
>>>lines in the Burger.
>>>
>>>I am Quite Partial to the  B2B  and  Know its Absolutely Wonderful
>>>Riding Qualities from experience.       What you say about the B2B being
>>>between a B2 and B3 may be true from an engineering standpoint, but I
>>>would Far Rather Ride a  B2B  than Either a B3 or B2.       The B2B
>>>performance on city prw was excellent  --  would liked to have
>>>experienced the same on Interurban prw.
>>>
>>>How this all affects maintenance may be another story altogether.
>>>
>>>Jim__Holland
>>>
>>>Boris Cefer wrote:
>>>
>>>      
>>>
>>>>No no no! The B-2 is softer vertically (=> bouncing), while the B-3 is
>>>>in vertical direction stiffer and thus better for prw with rail joints
>>>>in poor condition (but relatively straight vertically).
>>>>The B-2 does not transmit lateral irregularities of the track to the
>>>>body as much as the B-3.
>>>>As for the B-2b, the truck bolster was laid on the truck frame
>>>>somewhat higher than on standard B-2, from which I deduce that the
>>>>riding quality on B-2bs was a transition between B-2 and B-3, but
>>>>closer to B-2.
>>>>
>>>>Boris
>>>>
>>>>----- Original Message -----
>>>>From: "James B. Holland" <PRCoPCC at P-R-Co.com>
>>>>To: <pittsburgh-railways at dementia.org>
>>>>Sent: Thursday, January 27, 2005 7:16 PM
>>>>Subject: [PRCo] Re: Nosing
>>>>
>>>>
>>>>        
>>>>
>>>>>You Say It So Nicely!
>>>>>
>>>>>So in theory, the B2 would provide a better ride on open prw than the
>>>>>B3 -- yet theoretically the B3 was designed Just For That kind of
>>>>>operation!!!!!!!
>>>>>
>>>>>
>>>>>Jim__Holland
>>>>>
>>>>>
>>>>>
>>>>>Boris Cefer wrote:
>>>>>
>>>>>          
>>>>>
>>>>>>The problem of B-3 is obvious. The main (coil) springs are higher on
>>>>>>B-3 than on B-2, which means that the B-2 truck is laterally stiffer
>>>>>>than B-3. In addition to that, on B-3 trucks the car body rests on
>>>>>>the truck frame at higher point than on B-2s. The B-2 truck bolster
>>>>>>design is selfcentering and the weight of the car body drives it to
>>>>>>its lowest position (the result is automatical dampening). Also the
>>>>>>tapered tread plus inadequate gauge clearance (bad track) provides
>>>>>>very good excitation for lateral motions of the truck and whole the
>>>>>>car body.
>>>>>>
>>>>>>Boris
>>>>>>
>>>>>>----- Original Message -----
>>>>>>From: "James B. Holland" <PRCoPCC at P-R-Co.com>
>>>>>>To: <pittsburgh-railways at dementia.org>
>>>>>>Sent: Thursday, January 27, 2005 6:41 AM
>>>>>>Subject: [PRCo] Re: Nosing
>>>>>>
>>>>>>
>>>>>>            
>>>>>>
>>>>>>>Can be a variety of things.
>>>>>>>
>>>>>>>[[Snip]]
>>>>>>>
>>>>>>>It needs to be recognized that all *hunting__is__Not__hunting* --
>>>>>>>the differences in design between the B2 and B3 make for different
>>>>>>>performance on the same track. There was a portion on Church Street
>>>>>>>here in SF outbound between 17th and 18th downhill that was quite
>>>>>>>rough -- a B3 equipped car slammed back and forth sideways while a
>>>>>>>B2 passed through with barely a disturbance. The Swing link
>>>>>>>possibly saved sideways motion on the car on a B2 truck as the
>>>>>>>truck itself moved back and forth on the uneven track -- the bad
>>>>>>>track was short enough that the motion was not transferred to the
>>>>>>>body. But the framing of the B3 truck would even get the spring
>>>>>>>pots moving from side to side which then transferred this motion to
>>>>>>>the body. The motion ceased when the car passed this brief section
>>>>>>>of bad track -- that would not happen with hunting -- hunting seems
>>>>>>>to intensify once begun until measures like purposely slowing are
>>>>>>>taken to alleviate
>>>>>>>              
>>>>>>>
>>>>same.
>>>>
>>>>        
>>>>
>>>>>>>This same type of situation is pointed out in the PCC books about
>>>>>>>Chicago B2s and B3s on rough track -- considerably sideways action
>>>>>>>to the B3 whereas it is hardly noticeable on the B2.
>>>>>>>
>>>>>>>Yes, the B3 was developed for open track but have said before that
>>>>>>>the B2 did just fine from a ride standpoint -- don't know if it was
>>>>>>>more problematic for maintenance. Would Dearly Like To Know what a
>>>>>>>ride on the interurban would be like with the *Original__B2Bs* ----
>>>>>>>A Truly Superb Ride And The ONLY equipment I have ever ridden that
>>>>>>>aptly fit the description of *Riding__On__A__Cloud!*
>>>>>>>
>>>>>>>
>>>>>>>Jim__Holland
>>>>>>>              
>>>>>>>