Throttle Valve Seat Angles

Russ Fischer · **Posted:** Mon Sep 24, 2012 11:13 am

I am looking for information about the seat angles on a Baldwin dome throttle. Most of the throttle valves I have seen have different angles on the top and bottom seats. Something like 45 Deg. on the top and closer to 60 Deg. on the bottom. After repeated grinding in over the years the original dimensions tend to wander a bit.

Does anyone have the Baldwin specs for seat angles, or a Baldwin dome throttle drawing they could share?

Thanks.

Russ

Paul Boschan · **Joined:** Mon Mar 14, 2011 6:45 pm **Posts:** 89

I have built 3 Baldwin style dome throttles for NPS 2-1/2 dry pipes. In all case the seat angles were 45°. This was based on an original Baldwin valve one of the newly constructed valves replaced.

Mark D. · **Posted:** Mon Sep 24, 2012 12:51 pm

Consider using 45 degrees for the valve and 42 to 43 degrees on the seat. This allows for better seating as the valve wears in.
Mark D.

M Austin · **Joined:** Sat Feb 05, 2005 1:05 am **Posts:** 488

In the Grove Farm parts room is a factory new throttle valve spool. The valve angle on both seats is 45 degrees. The key to perfect tightness is indexing the height difference between the surfaces of the spool, then renewing that distance in the throttle casting at a perfect 45 angle. Lapping becomes simple then.

Kelly Anderson · **Joined:** Tue Sep 14, 2004 7:52 am **Posts:** 2477

Russ Fischer · **Posted:** Wed Sep 26, 2012 9:58 pm

Thanks to all for the information and the drawing. It is interesting, between the information posted here and another drawing I recently found I have seen 20, 30, and 45 degree seat angles used. (My original reference to 60 should have been 30 degrees.)

Kelly, does #90's throttle still have the pilot valve in it? The throttles on the C&TS K-36's were the same type but the pilot valves had been eliminated in all of them. I wonder if they were a maintenance problem or the mechanical department just decided they weren't necessary.