What determines the size of the main air reservoir (sp?) on a narrow gauge (or broad gauge for that matter) locomotive. I understand a mountain line would require more braking capacity. Thus the large air tanks on the back of a C-16 tender as compared to the much smaller air tanks you will find on say the Keeler branch locomotives - or is it all in my mind and an optical illusion?
How does one determine the size of tank needed? How much air capacity is required?
Thanks for any input on what may seem like an obscure question.