Build by the Illinois Central Railroad at its' Burnside shops in Chicago with the instruments provided by the University of Illinois (the car jointly owned).  The dynamometer car is a rolling laboratory that tests the pulling power of locomotives.  The front coupler is attached to the frame by a hydraulic cylinder.  The pull of a locomotive moves a piston in the cylinder and measuring instruments in the car record the data.  The system is so sensitive it can detect the force of a person pulling on the coupler and so strong that it tested an engine pulling a 213 car coal train.  Number 30 is 60' long, weights 125,000 lbs.  and contains as operating compartment with recording table, instruments and tool bench, as 2 staterooms which accommodates 4 people each, toilet, shower and kitchen.  This car was last used behind a steam locomotive in 1952 and was only used once behind a diesel-electric in 1955.  It was donated in 1969 by the Illinois Central Railroad and the University of Illinois.