Brakes

[Jim Holland]

Greetings!

	I found the Url for Siemens and under the details page
(http://www.sts.siemens.com/ProdServ/Projects/MTD/pittech.html) I found
this information.  It seems to be all-electric in braking function with
a spring applied, electromechanically released disc on each axle (this
is similar to the brake actuator mounted externally on the all-electric
PCCs - most PCCs were set up to be spring applied, electrically released
- TTC was an exception, at least on the ex-Kansas City Cars).  However,
on this page
(http://www.sts.siemens.com/ProdServ/Projects/MTD/pittsb.html) it says
the friction brake is pneumatic!
	As far as *air* on the car is concerned, an air bag is used for
secondary suspension.
	What is really interesting is that the trucks do not use kingpins -
they use slewing rings.  Found this out when I was working with the NMRA
on updating their Data Sheets.  A slewing ring is three concentric rings
that rotate on ball bearings within each other - the outer ring is
mounted to either the car body or the truck with the inner ring mounted
to the other and they rotate about the center ring!  The following is
quoted from their page:

"Siemens' Bogies"

	"The bogie frames are of light weight fabricated steel design under use
of hollow beam sections. The primary suspension is a chevron type spring
which also controls the position of the axle. Air bags are used as
secondary suspension and also transmit the lateral forces. Vertical and
lateral oscillations are hydraulically damped."
	"A ball bearing slew ring connects the car body with the bolster, which
in turn, is linked to the bogie frame by two traction bars."
	"Each powered bogie carries a longitudinally arranged mono-motor with
two helical bevel gearboxes. A spider type coupling connects the hollow
shaft of the gearbox with the wheelset and forces from acceleration and
deceleration are transmitted through rubber elements."
	"One brake disc is mounted on each axle; braking is accomplished by
spring applied, electromechanically released brake actuators."
	"Further components are track brake, slip/slide control, rail guard,
and fender skirts over the wheels. The non-powered bogie under the
articulation follows the design principles of the powered bogies. It is
equipped with one brake disc per axle."

James B. Holland
------- -- ---------
        Pittsburgh Railways Company (PRCo), June of 1949 -- June of 1953
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