Those companies employed a super-carpenter called a pattern maker who made giant gears and levers and thingbobs out of wood. The patterns were packed into a sandbox, carefully lifted away and molten iron poured into the hole. Simple stuff. You've probably seen nicely painted wooden gears on display somewhere; they're still pretty common. Look closely at our steam donkeys and you'll find traces of the sand-casting process.
The donkey has maximum torque when it's just starting to pull, so you the operator don't need the clutches and multiple gears you'd need with diesel power. No need to rev it up before you start to haul. Open a valve on the right piece of steam piping and away she goes.
The Willamette donkey was still at work here in 1949. Pete Duralia, who ran it and should know, said it was so strong that it could break its choker cables on a heavy load. All you had to do was get your helper to hold down the safety valve with a 2x4 to build up extra pressure!
Our steam drill landed off a barge in 1911 near where it now sits. It set out for the Yakoun Valley to drill for coal and arrived over a year later -- 50 kms. You can drive that distance today, even on gravel, in about an hour.
Boilers take hours to work up a head of steam, so you'll want to keep the fires banked up overnight. Water supply has to be completely reliable, too. Steam expands 1,700 times from a volume of water -- if the water runs out the last couple of gallons flash into steam and the boiler 'expands' too, like a bomb.
So now that you can see some of a donkey's abilities and shortcomings, you'll be on the lookout for something better. Certainly there's no way you could log with a steam donkey in today's woods.
People used diesel donkeys for a time but a stationary diesel winch is still an awkward workmate, and now you have to pack fuel to wherever its working. Its noisy and it smells worse!