I am new to this forum and am looking for info on how the valves were operated on the large stroke engines of sternwheelers. I am familiar with steam locomotive valves of different types, but am confused about sternwheelers. I see the pitman arms and cranks on the stern wheels but I don't see any eccentrics or eccentric rods next to them. How were the valves operated?

If anyone has any pictures of any of these valve operating methods they would be appreciated.

Thanks, Jeff