Rare Ames Steam Engine: Ames Iron Works Design Prone to Boiler Explosion

Early engines didn’t run under very high pressure (the Ames ran at 100 to 150 pounds). But when they exploded, they were no less dangerous. Boiler walls ranged from 1/4 to 5/16 inch thick, but for the bigger steam traction engines, that wasn’t big enough. “Those had to be 3/8 inch thick,” Mark says, “but they didn’t have machinery to work metal that thick.”

Early drive trains, shafts, bearings and bracketry were also problematic. “Those early steam engines, like the Ames, were pretty low-speed, high-torque machinery,” he says, “and to handle those torque loads you need some pretty massive stuff.”

Ratings hard to nail down

Inconsistencies with horsepower also presented challenges. “Before 1910, a horsepower was always a horsepower,” Mark notes, “but it depended where you got it from.” Nominal horsepower was subjective, and related to the work an average horse could do – but whose “average”? Brake and engine horsepower were actually measured.

For example, if the Ames was rated as a 12 hp engine, that meant it would do the work of 12 average horses. But that work depended on what an “average” horse was. Twelve Clydesdales would obviously outwork 12 Shetlands.

Mark says you can see the same thing in his 110 hp Case engine. “Before 1910 it was rated 32 hp,” he says. “After 1910, it was re-rated at 110 hp, because then it was actually scientifically measured. Brake horsepower was an actual measured output. Nominal wasn’t.”

The ratings were created to give the buyer, whose last “tractor” was a horse, some idea of what he was getting. The year 1910 seems to have marked a sea change in steam thinking, Mark says.

No hobby for the faint of heart

Mark’s first steam engine was a 110 hp Case. “My uncle owned it, and it had been idle for a couple of years,” he says. “The boiler had gone bad. He said if I found a boiler, changed all the parts and restored it, I could have it, so that’s what I did. I finished it in 1989, when I was 23.”

Mark quickly learned that the most difficult part of restoring a steam engine is boiler repair. “Any time you get into that, it’s usually hard work and time consuming. You have to work with the government,” he says. “If you want to repair it you have to get it approved, then have it inspected to sign off on the repair, and then have the entire machine inspected.” That final inspection is conducted on-site at the owner’s expense.