Slim Critchlow sang it somewhat differently:

THE TRUSTY LARIAT
As recorded by Slim Critchlow on "Cowboy Songs: The Crooked Trail to Holbrook," Arhoolie/Smithsonian Folkways, 1999. [YouTube]

Through the high Sierry Mountains came an SP passenger train.
The hobos tried to ride her but found 'twas all in vain.

The conductor took the tickets, and he counted every soul.
The engineer looked straight ahead and the fireman shoveled coal.

The fireman was a cowboy, but do not think it strange.
He could make more money a-shovelin' coal than ridin' on the range.

But though he was a fireman and though he had to sweat,
He still remained a Western guy and he kept his lariat.

The train was way behind time and the passengers all were wild
When on the track a-sudden there strolled a little child.

Her golden hair in ringlets was a-hangin' down her back.
She little knew her danger great as she strolled along that track.

"My God!" the hog-head shouted, as he slammed on all the brakes.
"I'll never stop this train in time 'cause I ain't got what it takes.

“Oh, heaven help that wee tot!" he cried in accents wild.
"Can nothin' stop this SP train and save that little child?"

Then up sprang the cowboy fireman, and a gallant lad was he.
"Now, I will save that baby if I wreck the whole SP!"

He climbed out on the runnin' board and with tears his eyes were wet,
And in his hand, our hero brave had his trusty lariat.

He quickly dropped a fast loop 'round a pole beside the track,
And he tied the other end of it around the big smokestack.

He jerked that train right off the rails and he caused an awful wreck.
And our hero lay there in the ditch with the engine on his neck.

Oh, we will all remember that 45th of May,
For there were many gallant hearts all filled with fear that day.

They buried that poor fireman where the prairie winds blow wild.
He killed two hundred passengers but thank God he saved the child!