The CLASSIC TRAINS issue about 4-8-4's says that the Timken engine's weight on drivers could be changed from 33 tons to 31 tons for use on lighter track. What sort of mechanism was used to do this? Thanx for any info.
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Big bags of Helium! 
On a more serious note...movable devices in the spring rigging could shift some of the weight from the drivers to the pony truck or trailing truck.
On a more serious note...movable devices in the spring rigging could shift some of the weight from the drivers to the pony truck or trailing truck.
This is probably a dumb question,but I'm going to ask anyway. Once you get up to 30 plus tons does 2 tons either way really make much of a difference?
Not really.quote:Originally posted by SouthernMike:
This is probably a dumb question,but I'm going to ask anyway. Once you get up to 30 plus tons does 2 tons either way really make much of a difference?
That's why the feature never appeared on any other locomotives.
quote:Once you get up to 30 plus tons does 2 tons either way really make much of a difference?
It can make a difference on where a locomotive can operate, especially at speed.
The Timken Locomotive was built with the intention of operating it on as many class 1 railroads as possible. Because of that it was constructed to fit within tight clearances, was relatively light for a 4-8-4 and had the ability to shift weight off the drivers to the normally lightly loaded engine and trailing trucks when necessary to meet bridge weight limits. The mechanism was adjusted prior to operating over a line with axle weight limits below what the Timken locomotive could place on its drivers. It wasn't intended to provide extra adhesion if the locomotive lost it's grip on the rail in the middle of a run.
The need for this feature wasn't faced by railroads purchasing locomotives for operation on their own lines since they could simply spec a locomotive to meet their needs. When the Timken was purchased by the Northern Pacific the NP had no need to limit the weight on the drivers since they were already operating heavier 4-8-4s, one of the few railroads doing so at the time. And the low profile stack and sand dome weren't needed to clear bridges and tunnels on the NP to they were raised to improve drafting and sand capacity. Timken noted that the sand dome was too small in demonstration service. The Timken locomotive may not have started to slip more easily than other locomotives but once a slip started it was harder to stop due to the reduced friction of the roller bearings on the driving axles and the extra sand capacity was most welcome.
You can take all that with a grain of roller bearing grease since I'm an arm chair NP fan and two of the guys above have actually operated super power steam locomotives.
I know that all of the Chinese SY Mikados had two cylinders, one connected to the leading truck and one connected to the trailing truck that would take all the weight off of them and shift all the weight to the drivers for starting heavier loads. The 142 in Phillipsburg NJ still has the cylinders but all of it is disconnected.
Mathew
Thanks for all the information,guys.
