coal transports: gondolas or hoppers?

[sebamat]

Hello,

when did the RRs start using hoppers in big number for transporting coal? It was a gradual switch from the use of gondolas?
When were the last gondolas used for coal? (I am interested motly in mid-western RRs)

Thank you!

sebastiano

[daveklepper]

Some high gondolas are still used for coal, to power plants and transfer to barge or truck facilities that have rotary dumpers, literally turning the car nearly upside down.

[CSSHEGEWISCH]

Hoppers with bottom hatches have been in service since the 19th century. High-sided gondolas with fixed bottoms for coal service are dependent on rotary dumpers and generally began coming into use in the mid to late 1960's.

[sebamat]

You are right, I forgot the 'high volume' aluminium hoppers used today.
But I was thinking at the ' general purpose' gondolas

sebastiano