[PRCo] Re: Fineview___PCCs

[Jim Holland]

Good Morning!


> BC wrote:

> Wasn't the problem of all-electrics in lack of drum
> brake adjustment?     Maybe no. The soft adjustment
> of standard all-electric drum brake would provide
> very long stopping distance on steeper downgrade and
> the shoes would suffer heavy wear.

	Do you mean:

	1.>--	Lack of adjustment built into drums?

	2.>--	Lack of adjustment by maintenance teams?

	In either case, track brake had 2-settings, the
first being moderate.     Not at all unusual for moderate
track brake to be applied during normal service stop.
This would help make the final stop and once stopped,
then the track brake would release allowing drums to do
their job.     Most cars would hold but obviously
there will be exceptions with wear and tear!     And
if all else fails, hold the track brake on  --  Not
So Difficult.     Did it on occasion here in SF.     Had
one Baby-Ten (aka PRCo-1700 except believe the drums
were internal expansion on the B3s) at Church and 19th
Inbound where center door wouldn't close and car would
not hold in service latch.     Put the brake to the floor
activating the track brakes and hooked the brake there.
Car held.     Got out of seat and manually closed
center door, then continued!

	Problem with #1 above is that, without possibility
of interim adjustments, braking integrity is consistently
lost as the drums wear!




> Maintenance specification we use here for drum brake
> says that each car must be tested by removing of drum
> brake fuse and pressing power pedal to reach starting
> current of 290 Amps - drum brakes must hold the car
> (on dead level track).      290 Amps cause approximately
> the same traction effort as 9.5 % downgrade.      Sometimes
> we experience drums which are sufficient to hold the
> car at 350 Amps, which would be about 11.5 % downgrade,
> but this is with new brake shoes and freshly adjusted brake.

	Assume this is Dead-Empty Wehicle, No?! :)




> But if you find any drawing and cpecification for
> WAB drum brake and actuator at Arden (that would need
> some work - consign it to limbo), I can easily made a
> calculation and answer the question of maximum grade
> which allows drum brake operation.

> Or you can ask Tony, I think he has some experience]
> with 1700s.     I am curious what he knows about drum brakes.

	Do you mean Bernie Orient?     He seems to be
very much up on equipment specifications.     Know the
name Tony DeSensi but haven't seen him referenced in
Trolley Fare recently.




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Jim

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