Classic Railroad Tech Quiz, Pt.1

[J. Edgar]

 

3. What is the difference between an eccentric and a crank pin?

Bonus: Name as many types of valve gear as you can think of which were developed or in common use during the late '30s. (Valve gears are the timing mechanisms that control the direction and duration of steam injection and exhaust of the cylinders, two common examples are the well known Walschaert's and Stephenson's valve gears.)

 Good luck to you!
Matthew Imbrogno
-Mechanical Vollenteer, Arizona Railway Museum
www.azrymuseum.org

a crankpin is just that   a pin to which a crank is attached     an eccentric is a crank attached to a crank   used to led or follow the main crank with additional motion

bonus.....baker ( long and short frame )  southern   greisley  poppet    and im sure others ive missed

[WSOR 3801]

Gresley Conjugated valve gear.  UP did have one 4-12-2 with two sets of Walscheart gear on the engr's side, with the air pumps moved to the fireman's side to balance it out.

Some of the parts of the Baker gear were interchangable between engines. 

 

[jimrice4449]

Big Jim beat me to it!   The spelling (I think) is Gresely.

[BigJim]

Excuse my spelling, Greisley.

Fun with valve gears;

http://www.tcsn.net/charlied/

[Kevin C. Smith]

Eccentrics and cranks are very similar, and they perform the same function...

Alright, let's see how mechanically minded we are around here!
Matthew Imbrogno
Mechanical Vollenteer, Arizona Railway Museum
www.azrymuseum.org

Not only mechanically minded but a bit of a sociologist, too!

[Mimbrogno]

And we have a winner! Yes, Baldwin Disk is the third brand of driving wheel. Although it is very similar in apperance, it is not to be confused with the Boxpok design. The Boxpok and Baldwin Disk wheels where actually made in the same town, and even in the same foundry together, but were manufactured by two seperate companies, and were actually in competition with each other! (talk about you're hometown rivals!)  

Good job on the valve gears, you got quite a few of them listed, including poppet valves. Baker was used on some of the faster steam locomotives, including the NYC J3a. The Young and Southern valve gears were far less widely used styles. The Southern in particular has a very peculior motion, and is arranged kind of like a Walscheart gear on it's end. Young's gear was a derivation of Stephensons valve gear, using two eccentrics to run the motion work.

What about the valve gear for three cylinder locomotives, do you guy's know the name to that one?

Alright, I may have been a bit too tough on you with that eccentric vs. crank stuff. Even I'm having a hard time defining the two. So, here it goes:

The best way to describe the difference is by showing what gears used them. The walschearts used a crank, which like any other crank is a lever with a bearing on each end. The crank itsefl rotates around one baring, while the other is connected to a lever. In the Walscheart gear, the crank is the lever that is outermost on the main bearing on the drive wheels.

An eccentric is what is used on Stephenson's gear, two of them are used to drive the rocker box that drives the valve rod. The eccentric itself is the cam on the shaft that drives the eccentric rods. Clear as mud, right? Well, I'll have pictures for you soon!!

Matthew imbrogno
Mechanical Vollenteer, Arizona Railway Museum
www.azrymuseum.org

[Lost World]

Wasn't boxpok made by Baldwin?  Are they the same as "Baldwin Disk" drivers, or was that a different brand?  Hmmm....

Just taking a little stab at the valve gears in use question, the most widely used were of course Baker, Walscheart, and Stephenson.  There was also the Young valve gear, which if I remember correctly was used on a couple of different classes of UP steam (2-10-2 I'm thinking?)  Not sure as I got rid of my UP power books years ago.  THere was also the Southern valve gear; can't give a locomotive example.  Some poppet valve gears in use in the late 30's:  the Franklin Oscillating Cam arrangement as applied to Pennsy K-4s #5399 by Lima Locomotive in 1939; Caprotti poppet valves applied to Pennsy K-5 #5699 (removed in 1937 and replaced with Walscheart gear). 

[Mimbrogno]

Oh, I forgot to mention that I'm dealing with US locomtives. I don't have very much technical data on foriegn equipment.

-Matthew

[Mimbrogno]

Well we got a good start on the question about wheels! We have two of the three types; Scullin and Boxpok. Scullin is actually the name of a steel company that sold their specialized drivers, while Boxpok is the proper designation of another company that produced it. Can anyone give the actual name of Scullin's wheels, or identify the company which produced the Boxpok brand? 

We still have the third brand of wheels, examples of locos which used each kind of wheel, and the other questions as well. I'll give you a hint as to the wheels question; two of the brands were made in Eddystone.

I know the second question is tricky and kinda vague, but I'll give you a couple of hints. One style of side rod has been around since the beginning of steam, and was commonly used on all engines until about 1920. Thereafter it was used only on small engines. Another style of driverod was developed in 1935 by Alcoa Aluminum, and you might guess what it was made of.

The third question may seem to be a trick at first, but an eccentric and a crank are two different mechanical devices which are used in valve gears for the same purpose. I'm sure you've heard of an "eccentric crank", but that's really a misnomer. Eccentrics and cranks are very similar, and they perform the same function, but they are technically to very different devices.

Alright, let's see how mechanically minded we are around here!
Matthew Imbrogno
Mechanical Vollenteer, Arizona Railway Museum
www.azrymuseum.org

[JonathanS]

I know two of the drivers that were in common usage in the USA:  They are the Boxpok (Box Spoke) and the Scullin.  

There were a number of competing designs in Europe and Australia.

[PBenham]

! Wow, I'll have to hit the books, here.

[Mimbrogno]

It seems that these quizical discutions are getting pretty popular! Well, here's another one for you guy's to test you're railroad knowledge. This one's especially for you guy's at the roundhouse, the rivet counters, and mechanical fellows like me.

This quiz is all about the advancing technology of railroads in general and locomotives in particular. This is a Classic era quiz, so there won't be any subjects relating to the time past 1960. Also, most of these questions will feature locomotive equipment developed in 1920s-1940s. Tossed in with the regular questions, I'll add a few of the more interesting technical terms for you to define.

At the end of each question, I will go back and elaborate on the different aspects of the pieces in question, and explain why they are so significant to the railroading world. If you're really lucky, I might scan some of the diagrams and blueprints from my technical library as well!

The first part deals with steam locomotives and their running gear:

1. By the 1940's, several types of driving wheel designs had been developed. There were three major types of "streamlined" high speed driving wheels, each made by three competing companies. What were the names of the driving wheels, what company made them, and what examples of locomotives were equiped with them.

2. Advances had also been made in the development of driving rods. By the mid '30s, there were three general styles of connecting rods; name them and examples of locomotives employing them.

3. What is the difference between an eccentric and a crank pin?

Bonus: Name as many types of valve gear as you can think of which were developed or in common use during the late '30s. (Valve gears are the timing mechanisms that control the direction and duration of steam injection and exhaust of the cylinders, two common examples are the well known Walschaert's and Stephenson's valve gears.)

 Good luck to you!
Matthew Imbrogno
-Mechanical Vollenteer, Arizona Railway Museum
www.azrymuseum.org