Frog angles for Wye Turnouts

[Xengeance]

Alright, quick question (caution math-heavy terms incoming): When laying a Wye turnout, should the frog angle be measured between the diverging track and an imaginary track where the through track would be (as both tracks past the point of switch can be considered 'technically' diverging tracks), or should the frog angle taken between the two diverging tracks, causing the midpoint of the arc to lie on the imaginary through track?

Example: A typical #9 turnout with only one diverging track has a frog angle of approx. 6.36 degrees between the through track (the straight one) and the diverging track (the track that turns off into another direction). However, if this were a Wye turnout (where both tracks past the switch point are diverging, rather than one running along where the through track would be), would the frog angle be 6.36 degrees from each track to where the through track would be (essentially identical to dropping a left and right turnout on top of each other and removing the middle track, thus 12.72 degrees total between both diverging tracks), or simply 6.36 between diverging tracks, thus 3.18 degrees between a diverting track and the imaginary through track.

I hope I explained that clearly enough. :hehe:

 

[Bill69]

Alright, quick question (caution math-heavy terms incoming): When laying a Wye turnout, should the frog angle be measured between the diverging track and an imaginary track where the through track would be (as both tracks past the point of switch can be considered 'technically' diverging tracks), or should the frog angle taken between the two diverging tracks, causing the midpoint of the arc to lie on the imaginary through track?

Example: A typical #9 turnout with only one diverging track has a frog angle of approx. 6.36 degrees between the through track (the straight one) and the diverging track (the track that turns off into another direction). However, if this were a Wye turnout (where both tracks past the switch point are diverging, rather than one running along where the through track would be), would the frog angle be 6.36 degrees from each track to where the through track would be (essentially identical to dropping a left and right turnout on top of each other and removing the middle track, thus 12.72 degrees total between both diverging tracks), or simply 6.36 between diverging tracks, thus 3.18 degrees between a diverting track and the imaginary through track.

I hope I explained that clearly enough. :hehe:

Hi, I would expect it to depend on how far appart you want the straight sections after the Y turnout. If you want them at normal spacing I would say the frog angle should be 6.36 degrees, which would mean it is not acctually a #9 turnout. But if you want them far enough appart to get a building between them I'd go for the 12.72 degrees.

Hope this helps,
Cheers,
Bill69

 

[pommie]

As far as I am aware a No9 wye frog would have twice the angle of a No9 turnout frog as it is the diverging angle (from the straight) that is used.
And yes it is like laying two turnouts at the same place and removing the straight tracks

Cheers David

 

[RPearson]

I disagree. The frog angle is the angle between the divergent rails. It's the same for both wye and std turnout - with a No 9 frog the angle between the rails is 6.36 deg for wye and turnout. What's different is the radius of the track from frog to switch. In a wye it's approx twice the radius of the divergent track in the turnout for same frog angle or number. Wyes are much more friendly on trains passing thru them.

Bob Pearson

 

[pommie]

Went digging for the answer and found out I was wrong :hehe:

Cheers David