In my previous post, I introduced the topic of modeling passenger car diaphragms, starting with older cars like heavyweight Pullmans. I showed both the prototype appearance, and the old Walthers diaphragm parts for HO scale. (The post can be found here: https://modelingthesp.blogspot.com/2021/05/modeling-passenger-car-diaphragms.html .) In the present post, I want to continue with this topic.
First, I mentioned in that previous post that the Walthers diaphragm, though perhaps useful in filling large intercar spacings, is really too big for realistic spacings. It is easy to correct, as I pointed out; one fold or two folds can be removed, as desired (more on the criteria for doing so in a moment). Shown below is my 12-1 Pullman, Columbia Glacier, with a shortened Walthers diaphragm. This car, for those interested, has previously been described (see this post: https://modelingthesp.blogspot.com/2014/07/modeling-sp-passenger-cars-heavyweight.html ).
You may be able to tell, in the above photo, that the face of the diaphragm is about at the inner side of the opening in the coupler beneath it. This is my usual criterion for diaphragm depth. You can see it more clearly below. This geometry allows good performance on curved track, while maintaining near-contact of diaphragms on straight track, perhaps the best compromise.
I should repeat a comment from the previous post (link in top paragraph, above), that in later years head-end cars often lost most or all of the canvas bellows in their diaphragms, leaving the striker plate and not much else. To illustrate, shown below is a detail from a Wilbur C. Whittaker photo of SP 6188, a Class 60-B-2 car at Oakland on April 13, 1951.
In model form, this is fairly easy to duplicate; I showed my modeling of these minimal diaphragms in a previous post (that post is at this link: https://modelingthesp.blogspot.com/2014/06/modeling-sp-passenger-cars-part-5.html ). That same post shows my face plate drawing for making new styrene face plates. It also referenced my kitbash of an SP 70-foot baggage car with side windows, for a car that retained the top spring bar and a side fold of a bellows. You can see the diaphragm on that model below, with the top spring element visible.
Brass models of SP head-end cars have sometimes included these simplified diaphragm representations. Below is a photo of a Precision Scale Class B-60-10 car in HO brass; coupler is removed for clarity.
None of these models, in either this or the previous post in the series, include stabilizer rods. I will take up that topic in the next post in this series.