0 ▁to ▁ 1 5 5 0 ▁and ▁ 2 1 0 3 ▁to ▁ 2 1 3 8 . ▁▁ 1 9 1 9 : ▁Class ▁ 1 6 C , ▁numbers ▁ 8 1 2 ▁to ▁ 8 4 1 . ▁▁ 1 9 2 0 : ▁Class ▁ 1 2 B , ▁numbers ▁ 1 9 3 1 ▁to ▁ 1 9 6 0 . ▁▁ 1 9 3 5 : ▁Class ▁ 2 0 , ▁with ▁an ▁inherited ▁tender . ▁ ▁Classification ▁letters ▁Since ▁many ▁tender ▁types ▁are ▁inter change able ▁between ▁different ▁locomot ive ▁classes ▁and ▁types , ▁a ▁tender ▁classification ▁system ▁was ▁adopted ▁by ▁the ▁S AR . ▁The ▁first ▁letter ▁of ▁the ▁tender ▁type ▁indicates ▁the ▁classes ▁of ▁engines ▁to ▁which ▁it ▁could ▁be ▁couple d . ▁The ▁" M _" ▁tend ers ▁could ▁be ▁used ▁with ▁the ▁locomot ive ▁classes ▁as ▁shown , ▁although ▁engine ▁draw bars ▁and ▁intermediate ▁emer gency ▁ch ains ▁had ▁to ▁be ▁replaced ▁or ▁adjust ed ▁to ▁suit ▁the ▁target ▁locomot ive ▁in ▁some ▁cases . ▁ ▁Class ▁ 1 2 , ▁Class ▁ 1 2 A ▁and ▁Class ▁ 1 2 B . ▁ ▁Class ▁ 1 4 , ▁Class ▁ 1 4 A ▁and ▁Class ▁ 1 4 B . ▁ ▁Class ▁ 1 5 ▁and ▁Class ▁ 1 5 A . ▁ ▁Class ▁ 1 6 , ▁Class ▁ 1 6 A , ▁Class ▁ 1 6 B ▁and ▁Class ▁ 1 6 C . ▁ ▁Class ▁