I am looking for drawings and specifications for the American Front End throttle. If anyone has a set and could copy them please message me.

Thanks
bob K

Talk to SRI I know they have them and they might have it on disk now I know they where working on them.

Kevin Mayer

There were many different sizes and variations in shape all for a different application.

Did you need a specific version for a specific locomotive?

I have some drawings from an old "Loco & Car Cyclopedia", but those are not going to be real blueprints.

I think that company was a Baldwin owned company, if so the original blueprints are still available if you need drawings of a specific model. I think they are part of the Pennsylvania State archives. If you need the throttle for a specific locomotive, as long as it was a Baldwin and built after 1938, the blueprints for the throttle should be available.

Post more specific info and I might be able to help you further.

Well specifically the throttle is currently attached to the 3751. There isn't anything stamped to identify a particular model however this has a 2 3/16 pilot valve, A 3 25/32 A valve and five 4 3/8 main valves. There are two button style cam carriers and the throttle has the outboard style of roller bearing on the throttle cam shaft.

Now what do you have to say or help?

Its not possible to tell you what level of accuracy you need in your drawings without knowing what you have to accomplish and what condition the throttle and its parts are in. That is what I meant by asking you to “be more specific”, sorry I was not more clear.

I’ll start from what I know;

Seems like that Loco was a Baldwin, thats good for your cause. What year was it built? I'll go away and do some quick research .... Ok, It was built earlier than 1938, that might be bad, as all the pre-1938 stuff is mostly gone.

Does the Sante Fe historical society ( or other SF group) have the blueprints? Thats the first place I'd contact. The loco probably has its original throttle, but maybe not.

These are the questions you must answer;

What exactly are you having to do? What is damaged? What dimensions are you going to have to know (EXACTLY) in order to accomplish your project?

Answer those questions, then you decide if you need the exact drawings for your exact throttle (like if the main casting had to be replaced), or, can you get by using accurate drawings from a similar throttle that uses your throttles same parts that need to be repaired, (like if you needed to replace a common valve or a seat), or do you need some other option.

If you can not find the exact drawings you need, then you find the closes drawings you can and guess.

Its very complicated, I know, but those are the questions you have to answer before you, I, or anyone else can know what you need. That throttle is one of the more precise and complex to manufacture parts on that entire locomotive, other than the brake valves. Its one of the mass manufactured parts that have the most tooling and investment in its manufacture and it was and still would be very complex to manufacture and it has very tight tolerances that you probably can not guess at, and get it right, without some accurate drawings to help you.

I’ve helped enough, good luck.

The throttle installed was from the 1941 rebuild. I can verify that it is the modern version as the pull downs on the poppets are the stirrup type.

There isn't anything broken on the throttle casting or parts. What I am looking for are dimensions for all these: setting up cam end play, clearance for cam carrier button style bearings, sequencing, lift, balancing piston and balancing bore, poppet valves, and cam. This would all be for the stirrup type of poppet and cam.

Also preferred methods of restoring any dimensions by weld build up, gas, electric or other.

I have two responses so far with some literature being sent. What else can you add?