Photo taken from the side of a Heisler geared locomotive truck with one wheel raised showing its flexibility on uneven trackage at Erie, Pennsylvania. Photograph by Schauble.

Photo of a Heisler geared locomotive truck with the gear cover removed. Photograph by Schauble.

Photo of a Heisler geared locomotive truck with the gear cover removed at Erie, Pennsylvania. Photograph by Schauble.

Photo showing various parts for Heisler geared locomotives at Erie, Pennsylvania. Photograph by Schauble.

Photo showing firebox grate for wood burning Heisler geared locomotives at Erie, Pennsylvania. Photograph by Schauble.

Photo showing firebox grate for coal burning Heisler geared locomotives at Erie, Pennsylvania. Photograph by Schauble.

Photo showing gears, line shafts and universal couplings for Heisler geared locomotives at Erie, Pennsylvania. Photograph by Schauble.

Photo showing various parts for Heisler geared locomotives at Erie, Pennsylvania. Photograph by Schauble.

Photo of a Heisler geared locomotive motor assembly at Erie, Pennsylvania. Photograph by Schauble.

Photo showing the slide valve end of a Heisler geared locomotive motor assembly for use on a diamond type frame at Erie, Pennsylvania. Photograph by Schauble.

Photo showing the piston end of a Heisler geared locomotive motor assembly for use on a diamond type frame at Erie, Pennsylvania. Photograph by Schauble.

Photo showing the slide valve end of a Heisler geared locomotive motor assembly for use on a diamond type frame at Erie, Pennsylvania. Photograph by Schauble.

Photo looking at the end of a Heisler geared locomotive center truck used on three truck locomotives with bolster in place and frame bolster sitting on top at Erie, Pennsylvania. Photograph by Schauble.

Photo looking at the end of a Heisler geared locomotive center truck used on three truck locomotives with gear case covers and bolster removed at Erie, Pennsylvania. Photograph by Schauble.

Photo looking down on a Heisler geared locomotive center truck used on three truck locomotives with gear covers and bolster removed at Erie, Pennsylvania. Photograph by Schauble.

Photo looking down on a Heisler geared locomotive center truck used on three truck locomotives with gear covers removed at Erie, Pennsylvania. Photograph by Schauble.

Photo looking down on a Heisler geared locomotive center truck used on three truck locomotives with gear covers and bolster removed at Erie, Pennsylvania. Photograph by Schauble.

Photo looking at the underside of a Heisler geared locomotive center truck used on three truck locomotives at Erie, Pennsylvania. Photograph by Schauble.

Photo of the cab interior of a Heisler geared locomotive at Erie, Pennsylvania. Photograph by Schauble.

Photo of the cab interior of a Heisler geared locomotive showing the johnson bar and air brake valves at Erie, Pennsylvania. Photograph by Schauble.

Photo taken from the right side of a locomotive boiler for a Heisler geared locomotive at Erie, Pennsylvania. Photograph by Schauble.

Photo taken from the rear of the firebox of a locomotive boiler for a Heisler geared locomotive at Erie, Pennsylvania. Photograph by Schauble.

Photo showing the air brake distributing valve and related piping ahead of the cab on the right side of a Heisler geared locomotive at Erie, Pennsylvania. Photograph by Schauble.

Builder photo of Construction Number 1303 showing right side of 36 inch gauge H.C. Johnson Company 23 Ton Two Truck Heisler Geared Steam Locomotive Number 2 at Erie, Pennsylvania, June 1914. This locomotive was used for logging near Johns Wood, Michigan. Photograph by Schauble.

Builder photo of Construction Number 1518 showing right side of 36 inch gauge Hawley-McIsaac Coal Company 32 Ton, Two Truck Heisler Geared Steam Locomotive Number 15 at Erie, Pennsylvania, March 1925. This locomotive was used for mining coal near Madisonville, Kentucky. Photograph by Schauble.

Builder photo of right side of Construction Number 1472 showing Hattiesburg Saw Mill Company 63 Ton, Two Truck Heisler Geared Steam Locomotive Number 5 at Erie, Pennsylvania, January 1923.This locomotive was used for logging near Hattiesburg, Mississippi. Photograph by Schauble.

Builder photo of Construction Number 1517 showing right side of Harleigh-Brookwood Coal Company 36 Ton, Two Truck Heisler Geared Steam Locomotive Number 64 at Erie, Pennsylvania, March 1925. This locomotive was used for mining coal near Frackville, Pennsylvania. Photograph by Schauble.

Photo of Construction Number 47 showing right side of Hammermill Paper Company 95 ton, Heisler 0-8-0 Fireless Steam Locomotive Number 4 with four flatcars of pulpwood at the Hammermill plant at Erie, Pennsylvania, circa 1939. Photograph by Schauble.

Builders photo of Construction Number 47 showing left side of Hammermill Paper Company 95 ton, Heisler 0-8-0 Fireless Steam Locomotive Number 4 at Erie, Pennsylvania, 1939. This locomotive was used in the paper mill at Erie. Photograph by Schauble.

Builder photo of Construction Number 1256 showing right side of Hall-Leftwich Lumber Company 42 Ton Two Truck Heisler Geared Steam Locomotive Number 4 at Erie, Pennsylvania, July 1912. This locomotive was used for logging near Morristown, Alabama. Photograph by Schauble.