Milwaukee Road class F7, which is a major contenders for the fastest steam locomotives ever built, was on a run between Chicago and Milwaukee on the "North Woods Hiawatha" but  the right main crosshead froze in its guide 73 miles from Milwaukee.
On July 27, 1950, F7 #102 was on a run between Chicago and Milwaukee on the "North Woods Hiawatha." 73 miles from Milwaukee, the right main crosshead froze in its guide. The F7s are major contenders for the fastest steam locomotives ever built, as they ran at over 100 miles per hour (160 km/h) daily. 
