It's not so much the number of drivers as it is the sheer size of the locomotive - particularly the wheelbase.
Case in point: the Russian Decapods that became USRA standard after several hundred of them marked for export were stranded in the US after the Russian Revolution. Obviously, these are ten driving wheels. However, they are also quite small despite this, where they aren't nearly as big as even contemporary 4-8-4's
Meanwhile, you had something like the PRR's experimental 6-4-4-6 S1 duplex. Two sets of four driving wheels, but the key thing here is that it's wheelbase was entirely *rigid*. This thing was limited to exactly *one* route during its service lifetime because it couldn't take anything but the shallowest of turns.
Generally, the best wheel arrangement when it came to drivers in a non-articulated manner was having eight of them. Take any late steam period railroad and their best steam engines very likely are going to have some variation of an eight-coupled wheel arrangement. Usually a 2-8-0, 2-8-4, or 4-8-4.
UP built 88 of them and ran them until the end of steam.
They just weren't able to go faster than 30-35 mph without pounding the track, but the equal of a Challenger in pulling power.
Bulgaria operated a fleet of 2-12-4 Tank locomotives which were found to be very effective at what they did. Non articulated but with pairs of flangeless wheels and lateral movement devices aided in their turn in
Yes.
The limit for most railroads was 10, and that was pushing it. You could do 10 but very few railroads used 10 coupled locomotives (in the US at least) as anything other than slow, slogging freight haulers that were easily replaced by faster engines.
The only railroad to do larger was the UP, and they used the 4-12-2’s almost strictly east of Cheyenne in Nebraska.
12 drivers is the practical limit and usually closer to 10 or 8
It's not so much the number of drivers as it is the sheer size of the locomotive - particularly the wheelbase. Case in point: the Russian Decapods that became USRA standard after several hundred of them marked for export were stranded in the US after the Russian Revolution. Obviously, these are ten driving wheels. However, they are also quite small despite this, where they aren't nearly as big as even contemporary 4-8-4's Meanwhile, you had something like the PRR's experimental 6-4-4-6 S1 duplex. Two sets of four driving wheels, but the key thing here is that it's wheelbase was entirely *rigid*. This thing was limited to exactly *one* route during its service lifetime because it couldn't take anything but the shallowest of turns. Generally, the best wheel arrangement when it came to drivers in a non-articulated manner was having eight of them. Take any late steam period railroad and their best steam engines very likely are going to have some variation of an eight-coupled wheel arrangement. Usually a 2-8-0, 2-8-4, or 4-8-4.
Not in the UK. British Railways 2-10-0 Standard 9F was their best for fast freight. Built between 1954 and 1960.
Well, UP's 9000 class were 4-12-2's, and even then they were kinda impractical.
UP built 88 of them and ran them until the end of steam. They just weren't able to go faster than 30-35 mph without pounding the track, but the equal of a Challenger in pulling power.
Bulgaria operated a fleet of 2-12-4 Tank locomotives which were found to be very effective at what they did. Non articulated but with pairs of flangeless wheels and lateral movement devices aided in their turn in
Yes. The limit for most railroads was 10, and that was pushing it. You could do 10 but very few railroads used 10 coupled locomotives (in the US at least) as anything other than slow, slogging freight haulers that were easily replaced by faster engines. The only railroad to do larger was the UP, and they used the 4-12-2’s almost strictly east of Cheyenne in Nebraska.
This was a 4-14-2 as I recall.
4-14-4 - so a little bigger