Driver Counterweights

[echo]

Hello,

I've been going through the drawings of the S1B Niagara I purchased from the NYCSHS.

I noticed something with the drawings of the main intermediate and back driving wheel centres, which I cannot make sense of.

These three drawings show the counter weight offset from opposite of the crank by roughly 4.5 to 7.5 degrees. Which is understandable to improve the dynamic balance of the wheels. However there is no mention of a left and right handed casting on any of the drawings and only 1 pattern is referenced.

Would the locomotive run with the the counter weights leading on the left side of the locomotive and trailing on the right side of the locomotive?

Is this due to the cross balancing designed into the counterweights?

BTW the counterweight is directly opposite the crank on the front driver.

Any suggestions.

Thanks

[Fender]

This configuration was done to achieve “cross counterbalancing” as described in this link:
http://trumpetb.net/loco/cbal.html
As I understand the concept, the angular offset of the counterweights was designed to remediate the imbalance from the rotating mass on the other end of the axle (rods, crankpins, etc.) and has nothing to do with the direction of rotation. So, the fact that it “leads” on one side and “trails” on the other is irrelevant.

[Sandiapaul]

Are you building a Niagara? I hope so!

[gwrdriver]

The counterweights of a large number of inside-cylindered British locomotives, and 3-cylindered locomotives, are in odd (to our eyes) positions relative to their cranks for this same reason.

[echo]

to Fender

Thanks for the info and link. It would be interesting to see the calculations done to achieve the counterweight offset design.

to Sandiapaul.

Well I would love to but have little equipment, space, skills or money to do so.
However, I have been producing some scale 3D models and drawings from the original NYCSHS drawings in the hope that one day I can start to build a Niagara of my own.

To gwrdriver,

Again very interesting, and what about the 4 cylinder locos and their counterweights?

[gwrdriver]

I would assume some degree of dynamic counterbalancing was at least considered.

[little giant]

The drivers were counter balanced to reduce augmented pounding on the rails, so the rails would not be damaged. A good example would be using a 4 jaw lathe chuck with the material far away from center, when spinning you can feel the out of balance. Here is a tidbit that Harold Crouch told me, when balancing the counter weights in the drivers a shop mechanic would crawl inside the frame of the locomotive and run at speed down the track and note which wheel needs to be balanced. I don’t think OSHA would approve this method today.