[From nobody Mon Jan 14 08:17:49 2013 Received: from mta4.snfc21.pbi.net (mta4.snfc21.pbi.net [206.13.28.142]) by mail-sf1.pacbell.net (8.9.3/8.9.3) with ESMTP id JAA08534 for <pghpcc@mail-sf1.pacbell.net>; Wed, 24 Nov 1999 09:28:35 -0800 (PST) From: JacksoRE@STVINC.COM Received: from wodc7-1.relay.mail.uu.net ([199.171.54.114]) by mta4.snfc21.pbi.net (Sun Internet Mail Server sims.3.5.1999.09.16.21.57.p8) with ESMTP id <0FLP00JGHPVBV7@mta4.snfc21.pbi.net> for pghpcc@mail-sf1.pacbell.net; Wed, 24 Nov 1999 09:28:31 -0800 (PST) Received: from portal.stvinc.com by wodc7mr0.ffx.ops.us.uu.net with SMTP (peer crosschecked as: [63.75.14.242]) id QQhqsz24904; Wed, 24 Nov 1999 17:28:31 +0000 (GMT) Received: from notes.stvinc.com by portal.stvinc.com via smtpd (for [199.171.54.114]) with SMTP; Wed, 24 Nov 1999 17:19:09 +0000 (UT) Date: Wed, 24 Nov 1999 11:18:25 -0500 Subject: Re:FW: PCC Speed To: billvigrass@hillintl.com Cc: pgcraig@bechtel.com, pghpcc@pacbell.net Message-id: <OFAA777EEE.DC0DB764-ON85256833.005FE0A8@stvinc.com> MIME-version: 1.0 Content-type: text/plain; charset=us-ascii X-MIMETrack: Serialize by Router on Notes/STV(Release 5.0.1|July 16, 1999) at 11/24/99 12:27:20 PM X-Priority: 3 (Normal) Some, but not all, PCCs had a speed limit relay. It functions basically by dropping out power when the control is in the last field shunting notch and the current drops below a level for which the relay is calibrated. That point is fixed by the traction motor characteristic curve for each voltage, so with a high line voltage the dropout point will shift up by a factor roughly equivalent to the voltage increase. (if the line is increased by 100 v, the factor is: line+100/line, etc.) Unless you are a system with a lot of long downgrades (such as Shaker), there is not much need for another thing to keep calibrated. The published "safe armature speed" for the PCC was 50 mph. Such numbers are always conservative and take into account a minimum size wheel, a marginal motor commutator, etc, keeping in mind that the most severe load on the motor is high speed braking, where the motor is probably going to be putting out twice its rating. (the voltage across a pair of PCC motors in high speed braking is in the 12-1400 volt range, which is why the motors are in some respects a 600 volt motor used at 300 volts.) (and yes, you could run it at 6-700 volts, but it would run overspeed when it got much over 300 volts, so there would be little point) My experience with PCCs operated without any cutoff on a 650 volt or so line and a long downgrade on the P&W is that you can get somewhat above 55 mph, and that takes a good long run. So, I put any claims for speeds much above 45 in the highly questionable category. I recall a trip outbound on PRCO's Ardmore boulevard line (rte 87) aboard a 1600 with B-3 trucks on a downgrade where we pushed the car as fast as we could betwee traffic lights. When we stopped at the next light, motorists that we paced said we were going about 46 mph. Since the voltage out there was probably not terribly high, that sounds about right. regards, Russ J. ____________________Reply Separator____________________ Subject: FW: PCC Speed Author: "Vigrass, Bill" <billvigrass@hillintl.com> Date: 11/4/99 8:44 AM -----Original Message----- From: Jim Holland [mailto:pghpcc@pacbell.net] Sent: Thursday, November 04, 1999 8:54 AM To: pittsburgh-railways@dementia.org Subject: PCC Speed Greetings! This question is mainly intended for Dr. Fred Schneider, III! On other lists the topic of PCC speed has come up and one individual claims that he rode PCCs at 50 mph and he knows this because he was timing mileposts along the line (which system used mileposts on their streetcar lines where such sustained speed could be maintained?!?!) Another knows he was doing 60 mph because the motorman let him operate the car and the police stopped him and said he was doing 60 (the officer probably said he was *goin' like 60!* [some motorman was really in trouble, wasn't he?!]) While aberrations in equipment is possible and an occasional car might have a top speed of 45 mph (as opposed to the official 42 mph), I seriously doubt that a car or a number of different cars could be capable of sustained 50 mph on the level and would be concerned about safety downhill. And 60 seems like total fabrication. The Mt. Washington tunnel was close to a 6% grade and I believe the top speed uphill for a PCC on such a grade is 28 mph. A car going full bore up through that tunnel *sounded* like it was doing 50 but it was only 25-30 at the very most! The only place I know of where I *might* have experienced a ride at 50 mph on a PCC was on a 17 interurban on a PM rush hour trip on Library with Charlie Diehl! We got bogged down in traffic downtown and lost the interurban in front of us. Then we got held up by opposing traffic on the Overbrook single track (another Library car was on our tail as we cleared the single track!) As we left Hillcrest outbound, Charlie put it to the floor and the power cut as we passed Lindemere heading into the roller coaster dip and the power didn't come back in until the trestle before the road crossing before Brightwood! Somewhere in there we probably got close to 50 but we never sustained that. Incidentally, we had the power cut may times heading to Simmons and got back to Kings School before we passed our follower! ANY COMMENTS????!!!! James B. Holland ------- -- --------- Pittsburgh Railways Company (PRCo), June of 1949 -- June of 1953 To e-mail *off-list,* please click here: mailto:pghpcc@pacbell.net N.M.R.A. Life member #2190; http://www.mcs.net:80/~weyand/nmra/ ]