# ALCO HH series

The ALCO HH series was an early set of diesel switcher locomotives built by the American Locomotive Company (ALCO) of Schenectady, New York between 1931 and 1940, when they were replaced by the S series: the 660 hp (490 kW) S-1 and 1,000 hp (750 kW) S-2. They were ALCO's first diesel switchers to enter true series production, and among the first land vehicles anywhere to use the revolutionary diesel-electric power transmission.
The "HH" name stood for "High Hood", a name ALCO came eventually to use in an official context, but originally an unofficial name. Model designations such as HH600 are only semi-official. Original ALCO designations were either descriptive or based on the internal order/design number.
A total of 177 of the HH series was produced; comprising one prototype and four production models of varying power outputs.

## ALCO 600 (New Haven #0900)

The first HH series locomotive, ALCO demonstrator #600, was mechanically almost identical to later designs, but the appearance differed. The sides of the locomotive's hood sloped outward from top to bottom, and brake equipment was exposed beneath the cab. It rode on a unique pattern of trucks. After a period of demonstration on a number of railroads, the unit was sold to the New York, New Haven and Hartford Railroad as #0900. This number often was used to describe the locomotive, although the classification on the builder's data card was "404-OE-200". This first unit was built in July 1931.

### Diesel-electric power transmission

The locomotive was equipped with a four-stroke McIntosh & Seymour 531 straight-6 diesel engine, powering a General Electric GT551A1 main generator. Four nose-suspended GE-287-D traction motors in the trucks were geared at a ratio of 4.25:1 to the wheels; the motors were cooled by electrically driven traction motor blowers.

## HH600

The HH600 was nearly identical to the previous #0900 of the New Haven internally and mechanically, but it was clad in new bodywork, with a straight-sided hood and cab sides that came all the way to the frame. The HH600's were powered by 6-cylinder McIntosh & Seymour 531 engines of 600 hp (450 kW). They were built from July 1932 through May 1939; in all, 78 HH600s were constructed. The first-built units had sharp-edged front hood corners, but in 1934 ALCO employed industrial designer Otto Kuhler to clean up the appearance; he curved the corners and recessed the headlight, and all subsequent HH series units were of this style until another restyling in 1938 where the nose was further rounded. Late versions of this locomotive used the 6-cylinder 538 engine.

### Original buyers

| Railroad | Quantity | Road numbers | Notes |
| American Locomotive Company (prototype) | 1 | 600 (1st) | to New Haven 0900 |
| American Locomotive Company (demonstrators) | 5 | 1, 600 (2nd) | 1 to ATSF 2300 |
| American Locomotive Company (demonstrators) | 5 | 601 | to Lehigh Valley Railroad 105 |
| American Locomotive Company (demonstrators) | 5 | 602 | to Boston and Maine 1102 |
| American Locomotive Company (demonstrators) | 5 | 603 | to Delaware, Lackawanna and Western 401 |
| Atchison, Topeka and Santa Fe Railway | 2 | 2301–2302 | 2301 retired Feb 1, 1971 Relocated to Temple, TX 2302 to American Grain & Cattle |
| Belt Railway of Chicago | 2 | 302–303 | |
| Boston and Maine Railroad | 1 | 1101 | |
| Central Railroad of New Jersey | 4 | 1020–1023 | 1021 to Houdaille Construction Materials Co. |
| Chicago and Eastern Illinois Railroad | 1 | 102 | |
| Chicago and Illinois Western Railroad | 1 | 1 | |
| Chicago and Western Indiana Railroad | 1 | 1 | |
| Delaware, Lackawanna and Western Railroad | 7 | 402–408 | 405–406 to Erie Lackawanna as 322-323 |
| Elgin, Joliet and Eastern Railway | 1 | 209 | |
| Hoboken Manufacturers Railroad | 1 | 601 | |
| Illinois Central Railroad | 8 | 9006–9013 | Scrapped 1951 |
| Massena Terminal Railroad | 1 | 7 | |
| Michigan Limestone and Chemical Company | 2 | 101–102 | |
| New York Central Railroad | 6 | 614–619 | |
| New York Central (Boston and Albany Railroad) | 5 | 680–684 | Renumbered 806–810 |
| New York, New Haven and Hartford Railroad | 10 | 0911–0920 |
| Patapsco and Back Rivers Railroad | 7 | 54–60 | |
| Peoria and Pekin Union Railway | 1 | 100 | |
| Portland Terminal Company [Maine] | 4 | 1001–1004 | |
| South Buffalo Railway | 6 | 54–59 | |
| Steelton and Highspire Railroad | 1 | 31 | |
| Universal Atlas Cement | 1 | 4 | |
| Total | 79 | | |

## HH900

The HH900 was a 900 hp (670 kW) version of the HH series using a turbocharged version of the McIntosh & Seymour 531 engine. Both turbocharged models (HH900 and HH1000) needed a greater cooling capacity, and this was reflected in the larger bodyside radiator space of both models, which distinguishes them from the lower-powered HH600 and HH660. The 21 HH900 units were produced between March 1937 and January 1939, after which they were supplanted by the McIntosh & Seymour 538T-engined HH1000. Several HH900s were built with the 538T engine.

### Original buyers

| Railroad | Quantity | Road numbers | Notes |
| American Locomotive Company (demonstrator unit) | 1 | 101 | to CRI&P 730 |
| Birmingham Southern Railroad | 8 | 81–88 | |
| Elgin, Joliet and Eastern Railway | 1 | 402 | |
| Kansas City Terminal Railway | 1 | 50 | |
| Minnesota Transfer Railway | 3 | 90–92 | |
| Philadelphia, Bethlehem and New England Railroad | 1 | 207 | to South Buffalo Railway 70 |
| Reading Company | 2 | 40–41 | |
| Warrior River Terminal Company | 2 | 50–51 | |
| Youngstown and Northern Railroad | 2 | 211–212 | |
| Total | 21 | | |

## HH660

The HH660 started production in ALCO's lineup in October 1938; 43 examples were built until April 1940. It used a naturally aspirated version of the 6-cylinder McIntosh and Seymour 538 engine, producing 660 hp (490 kW). Externally, HH660s were indistinguishable from late HH600s.

### Original buyers

| Railroad | Quantity | Road numbers | Notes |
| American Locomotive Company (plant switcher) | 1 | 4 | |
| Atlantic Coast Line Railroad | 1 | 1900 | |
| Boston and Maine Railroad | 1 | 1162 | |
| Buffalo Creek Railroad | 1 | 43 | To Relco - 1966, to WNYRHS - 2000 |
| Chicago, Milwaukee, St. Paul and Pacific Railroad (“Milwaukee Road”) | 4 | 1600–1603 | Renumbered 980–983 980-981 to Relco 982 in Scottsdale, AZ 983 to III Transportation then Illinois Railway Museum |
| Delaware, Lackawanna and Western Railroad | 3 | 409–411 | 409–410 to Erie-Lackawanna Railway 324–325 |
| Elgin, Joliet and Eastern Railway | 3 | 210–212 | 211 to Gopher State Scrap and Metal |
| Erie Railroad | 4 | 302–305 | 305 to Erie-Lackawanna Railway, same number |
| Green Bay and Western Railroad | 1 | 101 | |
| Inland Steel | 1 | 50 | |
| Louisville and Nashville Railroad | 1 | 10 | |
| Maine Central Railroad | 2 | 951–952 | |
| Minneapolis and St. Louis Railway | 1 | D939 | To Glacier Sand & Gravel |
| New York, New Haven and Hartford Railroad | 10 | 0921–0930 | 0924 to Penn Central 9411 in 1969 |
| Northern Pacific Railway | 3 | 125–127 | Renumbered NP 600-602 NP 600 sold WWV 770 WWV 770 to RELCo. 770 RELCo. 770 to Port of Longview 770 Port of Longview #770 to Northwest Railway Museum, under restoration to NP 125. NP 601 to WWV 775 WWV 775 scrapped NP 602 to RELCo. 602, on display in CB&Q paint, Albia, Iowa |
| Southern Pacific Company | 3 | 1001–1003 |
| Tennessee Central Railway | 1 | 50 | |
| Wabash Railroad | 2 | 100, 150 | |
| Total | 43 | | |

## HH1000

The HH1000 replaced the HH900, with the new McIntosh and Seymour 538T engine, turbocharged to produce 1000 hp (750 kW), a 100 hp (75 kW) increase from the previous model. They were produced between May 1939 and December 1940; 34 were built. M&STL D539 was the only HH1000 built with the 531T engine.

### Original buyers

| Railroad | Quantity | Road numbers | Notes |
| American Locomotive Company (demonstrator unit) | 1 | 1000 | |
| Atchison, Topeka and Santa Fe Railway | 12 | 2310–2321 | |
| Atlantic Coast Line Railroad | 1 | 600 | |
| Birmingham Southern Railroad | 1 | 89 | |
| Chicago, Milwaukee, St. Paul and Pacific Railroad (“Milwaukee Road”) | 1 | 1671 | |
| Manufacturers Railway | 3 | 202–203 | |
| Michigan Limestone and Chemical Company | 4 | 103–106 | |
| Minneapolis and St. Louis Railway | 1 | D-539 | Renumbered 92; to Chicago and North Western Railway |
| Missouri Pacific Railroad | 1 | 9102 | |
| Newburgh and South Shore Railway | 2 | 1–2 | |
| Oliver Iron Mining Company | 7 | 900–906 | |
| Total | 34 | | |

## Specifications

| Overall length | 45 ft 2.75 in | 13.79 m |
| Between bolster centers: | 21 ft 3 in | 6.48 m |
| Truck wheelbase: | 8 ft 0 in | 2.44 m |
| Width over grabirons: | 9 ft 10 in | 3.00 m |
| Height above rails: | 14 ft 3 in | 4.34 m |
| Wheel diameter: | 40 in | 1.02 m |
| Fuel capacity: | | |
| Engine (HH600): | McIntosh & Seymour 531 | McIntosh & Seymour 531 |
| Power (HH600): | 600 hp | 450 kW |
| Engine (HH900): | McIntosh & Seymour 531T (turbocharged) | McIntosh & Seymour 531T (turbocharged) |
| Power (HH900): | 900 hp | 670 kW |
| Engine (HH660): | McIntosh & Seymour 538 | McIntosh & Seymour 538 |
| Power (HH660): | 660 hp | 500 kW |
| Engine (HH1000): | McIntosh & Seymour 538T (turbocharged) | McIntosh & Seymour 538T (turbocharged) |
| Power (HH1000): | 1000 hp | 750 kW |
| Main generator: | | |
| Traction motors: | | |
| Standard gearing: | | |
| Weight: | | |

## Surviving units

| Locomotive | Type | Built | Owner |
| Atchison, Topeka & Santa Fe #2301 | HH600 | 1937 | Temple Railroad & Heritage Museum |
| Buffalo Creek #43 | HH660 | 1940 | Western New York Railway Historical Society |
| Delaware, Lackawanna & Western #409 | HH660 | 1940 | Delaware-Lackawanna |
| Elgin, Joliet & Eastern #210 or Northern Pacific #127 | HH660 | 1940 | Monroe County Historical Society |
| Elgin, Joliet & Eastern #211 | HH660 | 1940 | Gopher Scrap, Mankato MN |
| Milwaukee Road #1601 | HH660 | 1940 | Relco? |
| Milwaukee Road #1603 | HH660 | 1939 | Illinois Railway Museum |
| Northern Pacific #125 | HH660 | 1940 | Northwest Railway Museum |
| Birmingham Southern #82 | HH900 | 1937 | Heart of Dixie Railroad Museum |
| Oliver Iron Mining #900 | HH1000 | 1940 | Lake Superior Railroad Museum |
A few HH-series switchers still survive in revenue service, and more are in museums. Working HH locomotives include an HH660 at Gopher Scrap in Mankato, Minnesota, one owned by the Western New York Railway Historical Society, and one from the Delaware-Lackawanna Railroad owned by Genesee Valley Transportation Company at Scranton, Pennsylvania. Another HH660, Northern Pacific Railway #125, is presently under restoration to her as-delivered appearance at the Northwest Railway Museum.
Among the preserved locomotives are an HH600, four HH660s and an HH1000. Birmingham Southern #82, the sole surviving HH900, is on static display at the Heart of Dixie Railroad Museum in Calera, Alabama.