Steam & Excursion > Valve Pilot, more recollections...

Earlier we were discussing the locomotive Valve Pilot for steam locos ...

For review the Valve Pilot was an early 'event recorder'... it displayed two loco operating factors: driver rotational speed ( in MOH) and the position of the valve gear operating range. It also had a spool-paper recording device ( over the top of the speed meter, with a seal-able access door), that traced the speed with one pen and recorded the valve gear position wth the second pen.

Opearionally, the intended purpose was to encourage the expansive use of steam by shortening the travel of the valves --as track speed increased.
As the speed increased, it swept the speed needle, clockwise, up the circular dial. The engineer was supposed to match the RED valve gear position-indicating needle over the speed needle, as the speed increased...all the way up to the maximum safe speed for the class of engine, so equipped....

It was a 'power-matching' scheme and the event recorder .
It's event recorder, ----paper tape record, marked in miles ---- that was most useful to the supervisory personnel....
The record was useful fo checking loco operation over divisions and various landmarks, also for early accident investigation efforts.

The valve gear " indicating needle" was operated by a cam shaped like a Valentine's Day 'heart' ---- it had two spiral curves, facing each other, with the top curves sharply turned towards each other.... the cam rotated up to 180 degrees, either forward or reverse. A roller cam-follower, was moved by the heart-cam, according to where the reverse lever was set by the engineer..
At rest, with the reverse lever 'centered', the RED needle would be pointing at the highest speed.
on the speed dial...like 100 MPH.
The corresponding center position of the reverse lever represents the shortest admission period for the stem into the cylinders.
Such as would be the case at maximum speeds.

As the engineer sets the reverser for starting, the RED needle would follow the the cam, as it was moved by the valve gear to full position
( either forward, or reverse....the cam had two curves, that moved the RED needle between 'zero MPH' to 110 MPH, or higher, --- according to the Valve Pilot model that matched the intended loco service : passenger or freight speeds..).

So when starting, the RED needle was over top of the speed needle, & both resting at Zero MPH...
Underway, as the speed increased, and the engineer 'hooked-up' the reverser, the valve travel shortened, and the Valve Pilot RED needle moved towards the speed needle. The engineer's positioning of the valve gear, would move the RED needle, independent of the speed needle.

The cam's curves were manufactured to always reflect the locomotive class's "highest efficiency" and maximum engine power, for the instant track speed......
However, "maximum power " demands only occur when starting and on up-hills.

Descending long grades, with a heavy train, has the cars bunched against the engine, pushing it down the hill. NO "max power" needed, here!!!
On the flat, continuous application of max power, soon has you exceeding the allowable track speed....at some point, the engineer eases-off on the power settings, and the train virtually coasts along---- at cruising speed, with virtually no , or low power input to the train....

So the Valve Pilot is of little use to the engineer on flat or descending grades.... going up hills, whether with or without the Valve Pilot, the engineer's experience, the grade, and timetable govern his speed and power settings.

So, the major benefit was the tapeed record, and the cumulative tape records for Division folks and engineering folks.
The NYC was a devoted consumer of Valve Pilot records and did a good job of documentation and historical filing of those tapes.

Eventually Barco Speed Recorders bought the valve pilot product line, dropped the RED needle, kept the recorder function.
NKP BERK 759 retained its Barco speed recorder, when restored by HICO and we sometimes recorded paper rolls of some of the fan trips...the records were kept at the HQ, Lebanon, NJ.
Don't know what happened to them....

W.

I used to wonder what it would have been like to have used the Valve PIlot. I had to depend upon my ears, seat of the pants and the back pressure gauge and wondered how that would have taped.

Frisco1522....

You probably ran the engine JUST FINE.... Probably even better than watching the RED needle...
The major drawback, with the ' Pilot, was that there was no commensurate record of the throttle position, or steam chest pressure.

Back pressure don't mean much on an oil burner.... the free air passage through the firebox was always regulated by the dampers and the draft...
With coal on the grates, The ash build-up on the grates restricts the free air flow, builds up the bed depth, the engineer'd drop her down a couple of notches and make her bark louder....pretty soon the back pressure beneath the nozzle, increases, and the piston starts stuffing more steam up the stack...and increasing the "back pressure ...". Too high, that's not a "good thing"!

Valve Pilot won't help in those circumstances...

Maybe, if you had a fleet of steamers, Valve Pilot equipped, you could tell a lot more about how your crews were doing...
But a good Road Foreman, making his observations, and riding with crews could provide more effective feed back and advice.

SHE WAS FINE ENGINE WITH A DISTINCTIVE BARK,

Any mis-use of that machine, and she'd have made your life miserable...
Steamers are like that, and they don't even care!

W.

She was a fine engine and surprised more than a few people at how much grit she really had. I loved running her because of that shotgun exhaust and how well she responded. If you were running along at a steady speed, I would tweak the power reverse until I found what I called her "G" spot. The exhaust cadence was beautiful and had a real rhythm to it.
When running at a light throttle, the exhaust had a chirp to it which was annoying. We figured there must be some sort of a spot in the exhaust passage in the cylinder block.
One guy asked me why I never hooked her up. I did, but without the distinctive power reverse exhaust. I would start the train and get up to a few MPH and start just continuously bringing the lever back with the throttle at the same setting until we reached track speed. Worked for me. I think there's a video on my channel on Youtube of leaving a meet where I did this and if you listen you can hear the gradual exhaust change.
I'm gonna go cry now.

That engine was a good example of an ideal size-match...
As a 4-8-2, she was properly proportioned as an great passenger engine....

Berkshires tend to be a bit oversized, and Norhterns, too...
But many 4-8-2 engines were true "dual-purpose" machines....
,

Let's see...

There's the famous NYC Mohawks,, Lima's & Alcos
The Pennsy M1s,
The SP MT4(?) class,
N&W's K2 class,
B&M R class, with centipede tenders, ( I came across the L&HR 4-8-2s, virtual duplicates of the B&M engines...)
B&O?
NYO&W?


Any.I forgot?

W.



Edited 3 time(s). Last edit at 07/01/17 13:09 by wcamp1472.

Yes Wes, T&P's 10 4-8-2's. They worked freight very well.

4-8-2's were also used by
GN
UP
CRI&P
ATSF
SOU
MP
Wabash
SOO
L&N
B&A

USRA Light engines were used by
AGS
CNOTP
L&N
MP
NCSL
NH
NYO&W
SOO
SOU

USRA Heavy by
C&O
N&W
SOU

I don't know offhand it the USRA engines listed are duplicates of the earlier mentioned engines or if different designs. I suspect duplicates.

-John



Edited 1 time(s). Last edit at 07/01/17 14:15 by LarryDoyle.

wcamp1472 Wrote:
-------------------------------------------------------
> That engine was a good example of an ideal
> size-match...
> As a 4-8-2, she was properly proportioned as an
> great passenger engine....
>
> Berkshires tend to be a bit oversized, and
> Norhterns, too...
> But many 4-8-2 engines were true "dual-purpose"
> machines....
> ,
>
> Let's see...
>
> There's the famous NYC Mohawks,, Lima's & Alcos
> The Pennsy M1s,
> The SP MT4(?) class,
> N&W's K2 class,
> B&M R class, with centipede tenders, ( I came
> across the L&HR 4-8-2s, virtual duplicates of the
> B&M engines...)
> B&O?
> NYO&W?
>
>
> Any.I forgot?
>
> W.

Don't forget the great Paducah built Illinois Central 4-8-2's. The IC used them so well, they had UP upper management questioning the performance of their own "older power".

Scott Griggs
Louisville, KY

---

Any 4-8-2s running in today's age?

Any Favorite/ Best candidates to be restored?
Oil burners?

W.
.

LarryDoyle Wrote:
-------------------------------------------------------

> USRA Heavy by
> C&O
> N&W
> SOU

No for Southern.

How 'bout FEC
SSW
WP
CJV in Illinois

Wes, I thought I would add this photo of one of NYCentral's finest Mohawks, L-4 3149, which is equipped with a loco pilot valve, the external part visible just below the air tank.

---

Thanks...

Yes, NYC did a good job with office follow-up generated by analyzing the collected tapes...
So, if every engine was equipped ,and if you monitored the tapes, as a manager you could trap some common defects...

A common defect was caused by the power reverse correcting for 'drifting' shafts and bushings controlling the valve timing linkage.
It was a defect that affected the reverse shaft and the piston valve varies in its length of travel.....varying the admission, while traveling down the road .
The trace on the Valve Pilot tapes becomes a fuzzy blurr, rather than a clean line...

When the trace shows this type of 'wandering', it's easy to flag the engine, at the next scheduled maintenance period ...to correct he problem ..
There are other defects, too caught by religiously reading the tapes after the trips...

As an early 'event recorder' , it worked very well, aiding in running the train, not so much...

NYC used the Valve Pilots to a good advantage, in fleet-wide, maintenance & upkeep...

Thanks or posting

W.

My favorite 'Hawks were the few tthat were retrofitted with Full Timken roller bearing side rods...MAN! What I'd give to get one of those restored...
It's probably parked next to that 'famous missing ' J3a Hudson...

Oh, well...



Edited 2 time(s). Last edit at 07/02/17 18:17 by wcamp1472.