Baldwin locomotive smokebox handles

While looking through a narrow gauge Baldwin Locomotive Works catalog, I kept noticing one thing I found interesting. Behind every number plate was a single handle. I've heard of smokebox darts before, commonly used around the U.K. (however I've seen baldwin engines made for the Coahuila and Zacatecas that have them, also), which consists of 2 handles, 1 you rotate 90 degrees, 1 that's threaded to tighten/loosen the door. I've also seen cam style door openers that has a single handle to open the door by rotating it 90 degrees. However, most of the engines I was viewing seemed like the smokebox ring was too small for such a cam to work properly. So my question is, on smaller Baldwin engines would have they possibly just used the dart system, and eliminated the 90 degree arm, using the number plate to turn the dart into position instead? If anyone has any pictures of small Baldwin engines with such an arm behind the number plate, feel free to post. In advance, thanks for all the help.