Used on the Merchants, Bay State, and Knickerbocker Limiteds in the 1st two decades of the 20th century. Slide valves were replaced in 1917 by piston valves, at which time superheaters were added; see Locobase 8116.

Locobase 157 describes the first New Haven Pacific class as delivered in its saturated-boiler form. Beginning in 1917, the railroad began modifying these engines by installing a superheated boiler. The usual decrease in total heating surface induced by swapping many small tubes for a fewer larger flues was held to a relatively small figure. At the same time, the firebox gained some area with the addition of more arch tubes (the total impact on firebox heating surface now came to 29 sq ft) and the cylinders gained a little volume by growing an inch in diameter.

Interestingly, the 4-4-2 upgrade described in Locobase 8115 achieved almost the same power at speed because although the boiler was a bit smaller, the cylinders were smaller as well, which reduced demand. Moreover, the direct heating surface was little different. Total water evaporation was a bit higher in the 4-6-2 at 38,330 lb/hour, but the direct heating surface contributed only 11,045 lb/hour. Steam consumption could overmatch the boiler by achieving a theoretical 39,600 lb/hour; thus the boiler factor was 96.2%.

But of course the Pacific put more weight on the drivers and that proved a decisive advantage.

The superheat upgrade proved to be the last big change for the I-1s and they served the New Haven for decades more in that form. The first left service in 1944 and the last retired in 1951.

Drury (1993) says this class replaced the I-1s (Locobase 157) in mainline passenger service and also worked fast freights. Certainly it's a bigger locomotive with excellent proportions -- an adequate superheat ratio, large boiler, good factor of adhesion. Yet maximum water evaporation increased very little, up only 1,422 lb/hour to 39,752 lb/hour. Steam consumption grew at a faster rate, however, reaching 43,180 lb/hour and the boiler factor fell to 92.1%

Perhaps because of the lack of any real margin growth, the I-2s were overshadowed by the I-4s (Locobase 5465) that came on the road just 3 years later and relegated to secondary passenger traffic. In that role they served the line until the end of steam, being retired in 1948-1952.

To work the express-passenger Shoreliner service, the I-2 design discussed in Locobase 7590 was placed on taller drivers and given a boiler with longer tubes but four fewer flues. So the evaporative heating surface grew slightly, but the superheater area shrank. Total maximum evaporation rates changed little from the I-2, reaching 39,695 lb/hour. Maximum possible steam consumption remained 43,180 lb/hour.

It's little wonder, therefore, that the Shoreline duties were quickly filled by the I-4s when they began entering service in 1916 (Locobase 5465). The I-3s were relegated to secondary pasenger runs, they nevertheless served until the late 1940s.

Express Pacifics for the New York, New Haven & Hartford that headed the varnish between New York and Boston. For some very long trains (as many as 23 cars, e.g.), the New Haven would double up on I-4 power.

Compared to Brooks's I-2s (Locobase 7590), these engines had taller drivers and larger-diameter cylinders. RME shows the class as having 71 1/4 sq ft of grate area, but Locobase later ascertained through the NH 1962 Locomotive Diagram book (supplied in May 2005 by Allen Stanley from his extensive collection) that this was mistaken. In later years, they were easily distinguished by the Elesco feedwater heater mounted athwart the smokebox and, more unusually, by the air tanks laid longitudinally on each upper half of the boiler just behind the stack.

Later on, the New Haven made over some number (Locobase isn't sure how many) into superpower engines; see Locobase 7591.

As noted in Locobase 7591, the New Haven met the burgeoning demand for heavy passenger trains led to upgrades of some of the I-4s to a superpower standard (see Locobase 7591). This entry reflects another subset that used the original boiler layout but added 3 thermic syphons of 91 sq ft and modernized the Baker valve gear by fitting it with roller bearings.

As in the more extensive makeover, boiler pressure remained the same, but the cylinders shrank by 1" in diameter. The tender was much bigger and heavier.

The New Haven calculated that the augmented boiler evaporated water at the maximum rate of 49,730 lb/hour, of which the direct heating surface contributed 20,130 lb/hour. Compared to the maximum steam consumption rate of 46,840 lb/hour, the boiler factor came to 106%.

When delivered in 1916, the I-4 class (Locobase 5465) was a pretty potent express locomotive design. But as trains grew longer and heavier still, the New Haven began double-heading them. To meet the demand, the railroad procured the famed I-5 4-6-4s (Locobase 187) and modified some of the I-4s beyond the modest updates that appeared on the I-4-E (Locobase 12721).

The I-4-F rose to a superpower standard. In the makeover, boiler pressure remained the same, but the cylinders shrank by 1" in diameter, the Baker gear now used roller bearings, and the firebox received 91 sq ft of thermic syphons added to the firebox and combustion chamber. The tender was much bigger and heavier.

The big change came in the boiler. A redesign of the layout added considerable evaporative heating surface in not only the new combination of 2 1/4" tubes and 3 1/2" flue. Altogether, the design added about 25% in heating surface to the original I-4 boiler.

The New Haven calculated that the new boiler evaporated water at the maximum rate of 51,180 lb/hour, of which the direct heating surface contributed 20,130 lb/hour. Compared to the maximum steam consumption rate, the boiler factor came to 109.2%.

Specifications by Steve Llanso | |||||||
---|---|---|---|---|---|---|---|

Class | I-1 | I-1-a | I-2 | I-3 | I-4 | I-4-E | I-4-F |

Locobase ID | 157 | 8116 | 7590 | 9400 | 5465 | 12721 | 7591 |

Railroad | New Haven (NYNH&H) | New Haven (NYNH&H) | New Haven (NYNH&H) | New Haven (NYNH&H) | New Haven (NYNH&H) | New Haven (NYNH&H) | New Haven (NYNH&H) |

Country | USA | USA | USA | USA | USA | USA | USA |

Whyte | 4-6-2 | 4-6-2 | 4-6-2 | 4-6-2 | 4-6-2 | 4-6-2 | 4-6-2 |

Road Numbers | 1000-1031 | 1000-1031 | 1300-1349 | 1090-1095 | 1350-1399 | 1350+ | 1353+ |

Gauge | Std | Std | Std | Std | Std | Std | Std |

Builder | several | New Haven | Alco-Brooks | Baldwin | Alco | New Haven | New Haven |

Year | 1907 | 1917 | 1913 | 1913 | 1916 | 1930 | 1930 |

Valve Gear | Walschaert | Walschaert | Walschaert | Walschaert | Baker | Baker | Baker |

Locomotive Length and Weight | |||||||

Driver Wheelbase | 13.08' | 13.08' | 14.08' | 14.08' | 14.08' | 14.08' | 14.08' |

Engine Wheelbase | 33.45' | 33.46' | 34.46' | 36.10' | 36.10' | 36.10' | 36.10' |

Ratio of driving wheelbase to overall engine wheebase | 0.39 | 0.39 | 0.41 | 0.39 | 0.39 | 0.39 | 0.39 |

Overall Wheelbase (engine & tender) | 61.17' | 61.17' | 62.33' | 66.77' | 66.77' | 79.92' | 79.92' |

Axle Loading (Maximum Weight per Axle) | 46400 lbs | 54150 lbs | 60700 lbs | 60300 lbs | 61400 lbs | ||

Weight on Drivers | 142500 lbs | 142800 lbs | 154000 lbs | 161100 lbs | 165000 lbs | 178600 lbs | 180800 lbs |

Engine Weight | 229500 lbs | 234400 lbs | 251500 lbs | 259000 lbs | 266000 lbs | 287500 lbs | 291000 lbs |

Tender Light Weight | 134000 lbs | 134000 lbs | 132600 lbs | 132600 lbs | 154000 lbs | 298000 lbs | 298000 lbs |

Total Engine and Tender Weight | 363500 lbs | 368400 lbs | 384100 lbs | 391600 lbs | 420000 lbs | 585500 lbs | 589000 lbs |

Tender Water Capacity | 6000 gals | 6000 gals | 6000 gals | 6000 gals | 7500 gals | 16000 gals | 16000 gals |

Tender Fuel Capacity (oil/coal) | 14 tons | 14 tons | 13 tons | 13 tons | 12 tons | 16 tons | 16 tons |

Minimum weight of rail (calculated) on which locomotive could run | 79 lb/yard | 79 lb/yard | 86 lb/yard | 90 lb/yard | 92 lb/yard | 99 lb/yard | 100 lb/yard |

Geometry Relating to Tractive Effort | |||||||

Driver Diameter | 73" | 73" | 73" | 79" | 79" | 79" | 79" |

Boiler Pressure | 200 psi | 200 psi | 200 psi | 200 psi | 200 psi | 200 psi | 200 psi |

Cylinders (dia x stroke) | 22" x 28" | 23" x 28" | 24" x 28" | 24" x 28" | 26" x 28" | 25" x 28" | 25" x 28" |

Tractive Effort | 31559 lbs | 34494 lbs | 37558 lbs | 34706 lbs | 40731 lbs | 37658 lbs | 37658 lbs |

Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.52 | 4.14 | 4.10 | 4.64 | 4.05 | 4.74 | 4.80 |

Heating Ability | |||||||

Firebox Area | 204.40 sq. ft | 219 sq. ft | 217 sq. ft | 223 sq. ft | 298 sq. ft | 366 sq. ft | 366 sq. ft |

Grate Area | 53.40 sq. ft | 53.50 sq. ft | 53.20 sq. ft | 53.20 sq. ft | 59.20 sq. ft | 59.20 sq. ft | 59.20 sq. ft |

Evaporative Heating Surface | 3947 sq. ft | 3133 sq. ft | 3309 sq. ft | 3356 sq. ft | 3315 sq. ft | 3383 sq. ft | 3576 sq. ft |

Superheating Surface | 670 sq. ft | 780 sq. ft | 730 sq. ft | 776 sq. ft | 776 sq. ft | 1425 sq. ft | |

Combined Heating Surface | 3947 sq. ft | 3803 sq. ft | 4089 sq. ft | 4086 sq. ft | 4091 sq. ft | 4159 sq. ft | 5001 sq. ft |

Evaporative Heating Surface/Cylinder Volume | 320.40 | 232.69 | 225.70 | 228.91 | 192.66 | 212.66 | 224.79 |

Computations Relating to Power Output (More Information) | |||||||

Robert LeMassena's Power Computation | 10680 | 10700 | 10640 | 10640 | 11840 | 11840 | 11840 |

Same as above plus superheater percentage | 10680 | 12626 | 12662 | 12555 | 14090 | 14090 | 15155 |

Same as above but substitute firebox area for grate area | 40880 | 51684 | 51646 | 52628 | 70924 | 87108 | 93696 |

Power L1 | 9815 | 18538 | 18944 | 19832 | 18043 | 20190 | 30179 |

Power MT | 455.54 | 858.60 | 813.59 | 814.19 | 723.24 | 747.67 | 1103.98 |

- 1029 (I-1 at Boston 5/15/47, photographer unknown courtesy Carl Weber)
- 1091 (I-3 at Norwood, MA 06/1937, photographer unknown courtesy Carl Weber)
- 1335 (I-2 at Boston 9/21/50, photographer unknown courtesy Carl Weber)
- 1357 (I-4 at Providence 4/26/49, photographer unknown courtesy Carl Weber)
- 1396 (I-4 at South Boston 5/17/51, Don Hayward photo courtesy Carl Weber)