This is what was known as a "Railroad Hand-Pump Section Car". Probably once used by the Great Northern or the Milwaukee Road, it is in very good original condition, not even having received a new coat of paint in a few years.
The sign at the hand car:
The Railroad Hand-Pump Section Car is a simple track maintenance vehicle consisting of a platform built on 4 flanged railroad wheels and propelled by hand power. Rods, gears and cranks are utilized to enable the car to travel along the rails. A typical car could carry 4 to 6 maintenance workers, a Section Gang, whose duties included replacing worn or rotten crossties, tamping stone ballast between the ties and aligning rail to maintain the proper gauge and elevation. Other tasks included the inspection of track, rail replacement, vegetation control and line side equipment maintenance.