Nostalgia & History > throttle question

The Pennsy installed front end throttles on some locos. It looked like a box half burried in the smokebox. ONly ever heard of them in place on K4's. What is a front end throttle?
shane

Were the Pennsy fron-end throttles home-made? I have seen photos of them, and they are definitely add-ons. Did 4-8-2's get them too? This PRR throttle is not the late-1920's boxy type seen protruding from the top of the smokebox on some super-power locos.

Also, I have my own question: On some UP 2-8-8-0's and GN 4-8-2's, the cab was equipped with a front-end style throttle lever controlling a rod attached to a crank that went directly into the side of the steam dome. Was this a custom fit application by the railroad shops, or was there a standard "kit" for converting the regular back-head throttle rod mechanism to the rod that goes into the side of the dome? Also, I don't think that this arrangement had an equalizing lever in the rod as it went from the front of the cab to the dome.

What other locos had this style?

HB90MACH Wrote:
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> The Pennsy installed front end throttles on some
> locos. It looked like a box half burried in the
> smokebox. ONly ever heard of them in place on
> K4's. What is a front end throttle?
> shane

Front end throttles most always employed multiple valves that were operated via a cam in sequence...as opposed to the single, large spool of a conventional throttle valve. Additionally, the throttle was AFTER the Superheater, not BEFORE as in older power. This served to give the engineer a better chance at catching a slip.
Tom

Nitehostler is right and though mechanical dept engineers said the front end throttles were easier to operate I'm not totally sure that was completely correct. When running at speed you were still pulling against the pressure of the steam to open the throttle a couple more notches, especially with a Class Y6 pulling a heavy coal train when you were trying to get all the power she had when pulling grades. I've seen engineers put one or both feet on the backhead to get leverage while using front end throttles.

Regarding NRE973'S question (s); I'm not sure if PRR K-4 front end throttles were home built but it wouldn't surprise me. As far the throttle going to the steam dome; this was only to connect to the dry pipe via the outside rather than through the boiler but again it was said they were easier to operate. Some of the Russian Decapods 2-10-0's had their throttles in this arrangement but I'm not sure if it was from the factory as some didn't. I don't recall seeing any of this class from the Frisco with outside or front end throttles so I would speculate the outside throttles to the steam domes was an add on by whatever RR owned them. And no, I don't recall seeing any equalizing lever when the bar went straight to the steam dome. I should say that my experience was with Norfolk and Western locomotives and while I know a little about other roads engines I'm not as proficient as those that have studded them or work on them.

In my earlier post I made reference to the boxy type throttle on late 1920's power. This was the Bradford front-end throttle, and since it was mounted in the middle or front of the somkebox, I assume that it was simply mounted after the regular superheater header, rather than being part of it.

Great thread people. To those asking the questions and those answering, "Thank you". I have always enjoyed the mechanical / technical discussions and exchanges.