Re: Largest engine D&RG / Uintah

Les:
Funny you should mention that. My post got me thinking as to how the simpling (starting) valve on the Vauclain Compound worked, so I dug out my reprint of BLW's little book on thier compounds.
The simpling valve is on a pipe that connects both sides of the high pressure cylinder together. Then it is opened. Steam is allowed to go from one side of the high pressure piston to the other, then down through the piston valve into the low pressure cylinder. The pipe and valve also act as the cylinder cocks for the high pressure cylinder. Using this system in "simple", the high pressure piston does no work (it has live steam on both sides), the low pressure piston alone starts the train.
A 125 had 22 X 22 low pressure cylinders. Using the above formula, a 125 in simple had an increadible 45,254 lbs of tractive effort. With all that power a 125 in simple would have been a VERY slippery beast. If you went into simple out on the road and you were about to stall with the throttle into the tank and the Johnson bar in the corner, you'd better have a bunch of sand down and be ready for a serious kick! No doubt, running a 125 in simple for any time would have sucked the fire up the stack, along with all the water and steam!