[PRCo] B2 and B3 Trucks

[James B. Holland]

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
>>>