Dwarfed even by the freight cars it is switching, the diminutive No. 100 works the Galesburg yard during 1929, shortly after its purchase. Inefficient in this service, the Mack was soon relegated to the Galesburg tie plant, where it put in over 20 years of uneventful service. Hol also included the following detailed history of the Mack:

When the Q sought to buy its first internal combustion locomotive for switching service in 1928, it turned to none other than Mack again ( having earlier purchased gas-electric motorcar 501 in 1922 ), because EMC had nothing to offer in the switcher field. What the railroad got was a tiny 30-ton, rigid frame, four-wheel, center-cab gas-electric locomotive just over 16' long. Powered by a pair of four-cylinder. 85-hp Mack truck engines, the diminutive switcher utilized General Electric electrical equipment - generators and traction motors. Cooling radiators were mounted atop the cab roof instead of the more common "winter-front" position at the ends of the hoods. Built by Mack at its Plainfield, NJ plant in November 1928 ( c/n 172001 ), the locomotive was the first model AW turned out ( only three others followed ), and was used as a demonstrator. The Q acquired it on March 20, 1929, after testing it extensively in yard and industrial switching service at Lincoln, NE. Numbered 100, the little 170-hp center-cab machine was painted solid Pullman green with gold numbers and CB&Q initials. Immediately the 100 was assigned to Galesburg, where it worked industrial trackage and the railroad's tie plant. Designed to exert 18,000 pounds of tractive force at 30% adhesion below one mile per hour, 7,000 pounds at five miles an hour, and 4,000 pounds at 10 mph, the 100 supposedly could haul 650 tons at nine miles per hour on level track or 200 tons on a 1% grade at a lower speed. This made the locomotive inefficient in all but the lightest switching chores, so by the early 1930's the 100 was assigned strictly to the Galesburg tie plant ( and equipped with large buffer plates ). Beginning in 1932, 9000-series numbers were assigned to Q gas-electric ( and soon diesel-electric ) switching power, but the tiny 100, confined to the tie plant, was not renumbered to 9100 until October 1939. And it kept the number for just one year, because the operation department decided to differentiate tie plant switchers with their own numbers so that some unknowing dispatcher wouldn't inadvertently try to assign the little machines to regular switching duties. And so, in October 1940, the Mack AW assumed its third and final number: 8900. It continued its uneventful and little photographed life in the Galesburg tie plant until finally, in August 1952, the nearly 24-year-old locomotive was retired and scrapped.

The 9103, a single-unit order, was constructed in August 1940 ( c/n 12908 ) and delivered on September 4, the very first GE 44-tonner delivered. Milwaukee Road 1690 was also built in August, but it was delivered 10 days after 9103. Number 9103 was delivered in a very plain solid black but was soon repainted. It was withdrawn from service in 1969 and stored at Galesburg. The BN renumbered 9103 to BN 1 in July 1970 then was sold for scrap in November to Precision Engineering.

The 9103, a single-unit order, was constructed in August 1940 ( c/n 12908 ) and delivered on September 4, the very first GE 44-tonner delivered. Milwaukee Road 1690 was also built in August, but it was delivered 10 days after 9103. Number 9103 was delivered in a very plain solid black but was soon repainted. It was withdrawn from service in 1969and stored at Galesburg. The BN renumbered 9103 to BN 1 in July 1970 then was sold for scrap in November to Precision Engineering.

The 9103, a single-unit order, was constructed in August 1940 ( c/n 12908 ) and delivered on September 4, the very first GE 44-tonner delivered. Milwaukee Road 1690 was also built in August, but it was delivered 10 days after 9103. Number 9103 was delivered in a very plain solid black but was soon repainted. It was withdrawn from service in 1969 and stored at Galesburg. The BN renumbered 9103 to BN 1 in July 1970 then was sold for scrap in November to Precision Engineering.

Number 9104 was built in February 1941 ( c/n 12949 ) and along with 9105, 9106, and 9107, were the first Burlington center-cabs to come from the builder in the "new" paint scheme of black and gray with red and yellow striping. The little GE's held down switching and branch line assignments in eastern Nebraska, central Illinois, and all through Iowa. Reassignments were common. The 9104 later worked several assignments in Illinois, finally stored at West Burlington in 1969. It was assigned road number 4 by the BN ( not applied ), and was cut up at Chalen's Inc. scrapyard at the east end of the shop complex during September 1970.

Number 9105 was built in February 1941 ( c/n 12950 ) and along with 9104, 9106, and 9107, were the first Burlington center-cabs to come from the builder in the "new" paint scheme of black and gray with red and yellow striping. The little GE's held down switching and branch line assignments in eastern Nebraska, central Illinois, and all through Iowa. Reassignments were common. The 9104 later worked several assignments in Illinois, withdrwan from service nd stored at Galesburg during 1969. Road number BN 2 was applied in July 1970, then sold for scrap in November to Precision National Corporation.

When Porter 8902 at the Galesburg tie plant finally wore out and was retired in late 1964, the 9107 was moved to Galesburg as a replacement. Renumbered 8903, it was outfitted with the large buffer plates removed from the 8902. All five 44 tonners (9103 - 9107) were still on the roster at the time of the BN merger, but only two were actually still in service: 8903 at Galesburg and 9106 at Superior Nebraska. The only 44 tonner to actually operate on the BN was 9106 renumbered 3 shortly after the merger. It was used in and around Superior Nebraska. When the C&NW's Lincoln - Superior branch suffered a washout, rather than repair the damage, the North Western suspended service south of the missing bridge until shippers protested. The C&NW then arranged for its Superior agent to drive to the last town north of the washout, pick up the crew of the local, and bring them to Superior. The North Western crew worked the isolated end of the branch using BN 3, bring all the cars into Superior. Unfortunately the BN did not want the unit, so it was sold to Birmingham Rail & Locomotive Co. in April 1971, and the unusual operation ended. The 44 tonner was quickly resold, going to northern California's Camino Placerville & Lake Tahoe. During 1971 and 1972, the shortline rebuilt the locomotive, using the hoods from its Phase V 44 tonner 101 - still numbered as such. By mid-1974 the unit was renumbered 102 and lettered for the parent Michigan - California Lumber Co. It remained in use at last report.

Number 9120 was built in March 1932 ( c/n 50007 ) by the Whitcomb Locomotive Works of Rochelle, Illinois, ordered as number 112, delivered as number 9120. It was a 60-ton locomotive equipped with a pair of Climax Blue Streak eight-cylinder inline gasoline engines for a total of 400 horsepower. Westinghouse electrical equipment was used throughout. The trucks were the standard MCB ( Master Car Builders ) design produced by Commonwealth and were equipped with 36 inch diameter wheels and Fafnir-Melcher roller bearing journals. To improve visibility to motorists at grade crossings, the paint was adjusted from the traditional solid Pullman green to green body with a red cab and hood ends and radiator shutters in yellow, with red fuel tanks to indicate gasoline, yellow was used for diesel fuel. The full color Burlington Route herald was applied to the cab sides and circular white Safety First emblems were applied above the footboards. At an unknown date it acquired the standard Burlington switcher paint scheme.

When the 9120 was delivered, it was tested in several locations before settling down in the Wymore Division. Later, the locomotive worked several assignments in Iowa and Illinois. At some point it gained an equipment locker in front of the cab on this side, for what purpose I do not know. In July 1959 it was sold to shortline Illinois Midland ( Millington to Newark, Illinois ) where it operated until 1964, when both main generators burned up. It was retired and scrapped still wearing the Burlington paint and number.

Number 9120 was built in March 1932 ( c/n 50007 ) by the Whitcomb Locomotive Works of Rochelle, Illinois, ordered as number 112, delivered as number 9120. It was a 60-ton locomotive equipped with a pair of Climax Blue Streak eight-cylinder inline gasoline engines for a total of 400 horsepower. Westinghouse electrical equipment was used throughout. The trucks were the standard MCB ( Master Car Builders ) design produced by Commonwealth and were equipped with 36 inch diameter wheels and Fafnir-Melcher roller bearing journals. To improve visibility to motorists at grade crossings, the paint was adjusted from the traditional solid Pullman green to green body with a red cab and hood ends and radiator shutters in yellow, with red fuel tanks to indicate gasoline, yellow was used for diesel fuel. The full color Burlington Route herald was applied to the cab sides and circular white Safety First emblems were applied above the footboards. At an unknown date it acquired the standard Burlington switcher paint scheme.

When the 9120 was delivered, it was tested in several locations before settling down in the Wymore Division. Later, the locomotive worked several assignments in Iowa and Illinois. In July 1959 it was sold to shortline Illinois Midland ( Millington to Newark, Illinois ) where it operated until 1964, when both main generators burned up. It was retired and scrapped still wearing the Burlington paint and number.

Burlington's first diesel locomotive was not, as many seem to believe, the famous Pioneer Zephyr, but rather a lowly switcher from virtually an unknown builder. The Pioneer Zephyr was completed in April 1934, but did not enter regular service on the Q until Novermber 1934. By that time, CB&Q 9121, a diesel electric center-cab switcher, had been in service in and around Omaha for a full year. The 9121 was the first of only three railroad locomotives ever built by the Midwest Locomotive Works of Hamilton, Ohio. All three were ordered by the Q at the same time and they were delivered in October 1933 ( 9121, c/n 1073 ), August 1934 ( 9122, c/n 1074 ) and October 1934 ( 9123, c/n 1075 ). The 9121-9123, weighing 65 tons each, featured a pair of Cummins Model L-6 six-cylinder, four cycle diesel engines rated at 225 horsepower at 1,000 rpm, for a total locomotive horsepower of 450. Electrical equipment was from GE, including a pair of GT-1160-B-1 self-exciting main generators and four 714-B-1 traction motors. As with all the center-cabs, there were operating controls on both sides of the cab, making the locomotive totally bi-directional.

The 9121 was requisitioned by the U. S. Army during WWII, eventually becoming U. S. Army Transportation Corps 7196, later sold to Stockton Terminal & Eastern, becoming that California shortline's No. 10. Both the remaining Midwest locomotives led uneventful careers on the Q, working primarily in the Lincoln-Omaha-Saint Joseph area, and in Illinois. The 9122, after being stored for over a year, was retired on the last day of 1962, and dismantled the following May 17, while the 9123, last used as the Peoria switcher, was sold for scrap to Precision Engineering Co. in November 1965.

Burlington's first diesel locomotive was not, as many seem to believe, the famous Pioneer Zephyr, but rather a lowly switcher from virtually an unknown builder. The Pioneer Zephyr was completed in April 1934, but did not enter regular service on the Q until Novermber 1934. By that time, CB&Q 9121, a diesel electric center-cab switcher, had been in service in and around Omaha for a full year. The 9121 was the first of only three railroad locomotives ever built by the Midwest Locomotive Works of Hamilton, Ohio. All three were ordered by the Q at the same time and they were delivered in October 1933 ( 9121, c/n 1073 ), August 1934 ( 9122, c/n 1074 ) and October 1934 ( 9123, c/n 1075 ). The 9121-9123, weighing 65 tons each, featured a pair of Cummins Model L-6 six-cylinder, four cycle diesel engines rated at 225 horsepower at 1,000 rpm, for a total locomotive horsepower of 450. Electrical equipment was from GE, including a pair of GT-1160-B-1 self-exciting main generators and four 714-B-1 traction motors. As with all the center-cabs, there were operating controls on both sides of the cab, making the locomotive totally bi-directional.

The 9121 was requisitioned by the U. S. Army during WWII, eventually becoming U. S. Army Transportation Corps 7196, later sold to Stockton Terminal & Eastern, becoming that California shortline's No. 10. Both the remaining Midwest locomotives led uneventful careers on the Q, working primarily in the Lincoln-Omaha-Saint Joseph area, and in Illinois. The 9122, after being stored for over a year, was retired on the last day of 1962, and dismantled the following May 17, while the 9123, last used as the Peoria switcher, was sold for scrap to Precision Engineering Co. in November 1965.