Greetings, As I understand it, coach is synonymous with chair car. I did a little research and all of the articles I read use the two interchangably. I suspect the two were popular during different periods. Coach is most likley the newer name. Hope this helps. mike
Looking through my collection of All Aboard's (The ones put out by the Frisco Museum in Springfield) I found an answer to the question you had concerning the difference between a Coach and Chair car. The article is one in a series concerning the company service roster (MOW bunk cars etc.). This particular article concerned the conversion of Chair cars. Quoting from the article "The 'Poor man's Parlor Car.' That is what John White called the railroad Chair Car in his classic book 'The American Railway Passenger Car'. According to White, "The chair car was aimed at the parlor car market and at those coach passengers who wanted something better than a stiff-backed double seat. The big attraction was added luxury at no extra charge. Each passenger had a reclining chair that could be turned toward the scenery or the other way to converse with a neighbor across the aisle. At night it could be dropped back like a sofa, and while it was not as good as a berth, it was adequate for a snooze." The article continues, saying "that between 1904 and 1923 the Frisco purchased fifty-six chair cars which provided service on the Frisco for over sixty years. The last in the series to be removed form revenue service was 767, dismissed June, 1967." The article has a picture of a chair car at Paris, Texas, date unknown. It also has a blue print of the three cars that where rebuilt and streamlined for service on the Firefly. What is interesting about the picture and the blueprint is that it shows the seats to be two abreast (double seats?) as in a Coach. Apparently both seats must have pivoted as one. Anyway, I would imagine with the introduction of sleepy hollow seats and in later years the improvements made to chairs in coaches the Chair cars fell out of favor. Indeed, according to the article in the 40's and 50's a number of the cars where converted to other service including bunk cars for the MOW.
