PRR D16
Encyclopedia
Class D16 on the Pennsylvania Railroad
Pennsylvania Railroad
The Pennsylvania Railroad was an American Class I railroad, founded in 1846. Commonly referred to as the "Pennsy", the PRR was headquartered in Philadelphia, Pennsylvania....

 was their final development of the 4-4-0
4-4-0
Under the Whyte notation for the classification of steam locomotives, 4-4-0 represents the wheel arrangement of four leading wheels on two axles , four powered and coupled driving wheels on two axles, and no trailing wheels...

 "American" type of steam locomotive
Steam locomotive
A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...

.
A total of 429 of these locomotives were built, spread across five subclasses; some had 80 in (2,032 mm) diameter driving wheel
Driving wheel
On a steam locomotive, a driving wheel is a powered wheel which is driven by the locomotive's pistons...

s for service in level territory, while others had 68 in (1,727.2 mm) drivers for mountainous terrain.
In the pre-1895 scheme, these locomotives were second class L.

Construction continued until 1910, and the locomotives, aided by a rebuild program from 1914, remained in service in large numbers until the 1930s, a small number surviving into the 1940s. One locomotive, #1223
PRR 1223
PRR 1223 is the only preserved class D16sb of the Pennsylvania Railroad. The 4-4-0 sits on static display at the Railroad Museum of Pennsylvania in Strasburg. In the 1970s and 80s the 1223 ran on excursions on the Strasburg Rail Road also in Strasburg...

, was preserved and is currently on display.

Design

These locomotives were originally conceived as an enlargement of the earlier class P (later reclassified D14
PRR D14
Class D14 on the Pennsylvania Railroad was a type of steam locomotive with a 4-4-0 wheel arrangement in the Whyte notation.They were originally designated class P in the PRR's pre-1895 classification scheme...

) and were an extremely large and powerful locomotive for the period. Breaking with the traditional 4-4-0 layout with a low-slung boiler and the firebox between the frames, the class L design had a large Belpaire firebox
Belpaire firebox
The Belpaire firebox is a type of firebox used on steam locomotives. It was invented by Alfred Belpaire of Belgium. It has a greater surface area at the top of the firebox, improving heat transfer and steam production...

 above the frames
Locomotive frame
A locomotive frame is the structure that forms the backbone of the railway locomotive, giving it strength and supporting the superstructure elements such as a cab, boiler or bodywork. The vast majority of locomotives have had a frame structure of some kind...

 and a large high-mounted boiler. The high center of gravity
Center of gravity
In physics, a center of gravity of a material body is a point that may be used for a summary description of gravitational interactions. In a uniform gravitational field, the center of mass serves as the center of gravity...

 proved to offer an exceptional high-speed ride.

The design was the product of three men; general superintendent of motive power Frank D. Casaneve, chief mechanical engineer Axel S. Vogt, and chief of motive power Theodore N. Ely, Casaneve supervising the overall design, Vogt perfecting the mechanical details and Ely paying more attention to the appearance and external detail.

Two versions were conceived, reflecting the variety of terrain the PRR traversed; a high-drivered version for flat terrain with 80 in (2,032 mm) wheels and a low-drivered version for hilly terrain with 68 in (1,727.2 mm) wheels. The versions had tractive effort
Tractive effort
As used in mechanical engineering, the term tractive force is the pulling or pushing force exerted by a vehicle on another vehicle or object. The term tractive effort is synonymous with tractive force, and is often used in railway engineering to describe the pulling or pushing capability of a...

 ratings of 17500 lbf (77.84 kN) and 20600 lbf (91.63 kN), respectively. In the reclassification of 1895, the 68-inch drivered locomotives became class D16 and the 80-inch became D16a.

Production

73 of the high-drivered D16a subclass were built between 1895–1898, and 6 of class D16 in 1896. A slightly revised low-drivered subclass D16b was constructed to the tune of 262 examples between 1900–1908, as well as 12 high-drivered D16c in 1900 and 45 high-drivered D16d between 1900–1910.

As the American (4-4-0) type was displaced from top-flight service to secondary duties, tractive effort became more important than top speed. Large numbers of the high-drivered locomotives were converted to low-drivered; 76 D16a and D16c were converted to subclass D16, while 9 of class D16d were converted to D16b specification; this left only a small number of locomotives with 80-inch drivers.

Rebuilds

In 1914, the PRR experimentally rebuilt D16b #178 in the Altoona Shops, giving it superheat
Superheater
A superheater is a device used to convert saturated steam or wet steam into dry steam used for power generation or processes. There are three types of superheaters namely: radiant, convection, and separately fired...

 for greater power and efficiency. This necessitated replacing the slide-valve equipped cylinders, the lubrication of which was incompatible with the hotter, dryer superheated steam, with piston valves and slightly larger cylinders. Steam pressure was reduced by 10 psi (0.6894757293 bar) to 175 psi (12.07 bar). Tractive effort
Tractive effort
As used in mechanical engineering, the term tractive force is the pulling or pushing force exerted by a vehicle on another vehicle or object. The term tractive effort is synonymous with tractive force, and is often used in railway engineering to describe the pulling or pushing capability of a...

 increased to 23900 lbf (106.31 kN) from 20600 lbf (91.63 kN). The rebuilt locomotive was classified D16sb, the "s" referring to superheat.

The conversion proving a success, over the next few years 241 locomotives of various D16 sub-classes were converted to D16sb configuration, with 68-inch drivers. In addition, a number of high-drivered locomotives were rebuilt; these were classified D16sd.

Later career

Even by the early 1900s the 4-4-0 type was becoming eclipsed by larger types such as
4-4-2
4-4-2 (locomotive)
Under the Whyte notation for the classification of steam locomotives, 4-4-2 represents the wheel arrangement of four leading wheels on two axles , four powered and coupled driving wheels on two axles, and two trailing wheels on one axle...

 "Atlantics" in top-flight service, and the D16 locomotives became stalwarts on more pedestrian services; slower trains, locals, branch line service, and commuter services. The rebuilds to D16sb and D16sd gave them a new lease of life in such service, and even by December 1929 there were still 143 examples in operation, mostly in the Eastern and Central Regions. A number were sold to the small Kishacoquillas Valley Railroad in Lewistown, Pennsylvania
Lewistown, Pennsylvania
Lewistown is a borough in and the county seat of Mifflin County, Pennsylvania, United States. It lies along the Juniata River, northwest of Harrisburg. The number of people living in the borough in 1900 was 4,451; in 1910, 8,166; and in 1940, 13,017. The population was 8,998 at the 2000 census,...

, and the quantities in service with the PRR dwindled progressively as train lengths increased and newer locomotives trickled down, especially with the reduced traffic of Depression years and with steam locomotives made surplus by the railroad's electrification projects.

Last survivors

The last of the PRR's American types were found on the branch lines of the Delmarva Division, on the Delmarva Peninsula
Delmarva Peninsula
The Delmarva Peninsula is a large peninsula on the East Coast of the United States, occupied by most of Delaware and portions of Maryland and Virginia...

, encompassing parts of the U.S. state
U.S. state
A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...

s of Maryland
Maryland
Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...

, Delaware
Delaware
Delaware is a U.S. state located on the Atlantic Coast in the Mid-Atlantic region of the United States. It is bordered to the south and west by Maryland, and to the north by Pennsylvania...

 and Virginia
Virginia
The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...

. Three locomotives were left at the beginning of World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, numbers 1035, 1223 and 5079; of these, only 1223 retained its slatted passenger pilot
Pilot (locomotive)
In railroading, the pilot is the device mounted at the front of a locomotive to deflect obstacles from the track that might otherwise derail the train. In some countries it is also called cowcatcher or cattle catcher....

. This locomotive, a 1905 product of the Juniata Shops, was selected by the railroad for preservation as a historic artifact and was stored at Wilmington, Delaware
Wilmington, Delaware
Wilmington is the largest city in the state of Delaware, United States, and is located at the confluence of the Christina River and Brandywine Creek, near where the Christina flows into the Delaware River. It is the county seat of New Castle County and one of the major cities in the Delaware Valley...

 until 1951, following which it was placed in the PRR's historic collection in the roundhouse at Northumberland, Pennsylvania
Northumberland, Pennsylvania
Northumberland is a borough in Northumberland County, Pennsylvania, United States. The population was 3,714 at the 2000 census.-History:Northumberland was founded in 1772. The land that became Northumberland was purchased from the Iroquois in the first Treaty of Fort Stanwix in 1768, and the...

.

Strasburg Railroad

In 1960, the 1223 was leased and transferred to the Strasburg Rail Road
Strasburg Rail Road
The Strasburg Rail Road is a heritage railroad located near Strasburg, Pennsylvania. It operates excursion trains hauled by steam locomotives in the heart of Pennsylvania Dutch Country.Across the street lies the Railroad Museum of Pennsylvania...

, a tourist line in the Amish
Amish
The Amish , sometimes referred to as Amish Mennonites, are a group of Christian church fellowships that form a subgroup of the Mennonite churches...

 hamlet of Strasburg, Pennsylvania
Strasburg, Pennsylvania
Strasburg is a borough in Lancaster County, Pennsylvania, United States. It developed as a linear village along the Great Conestoga Road, stretching about two miles along path later known as the Strasburg Road...

, where it was returned to operating condition. It operated tourist trains there until 1989, successively leased by the PRR, its successor Penn Central from 1968, and the Railroad Museum of Pennsylvania
Railroad Museum of Pennsylvania
The Railroad Museum of Pennsylvania is a railroad museum in Strasburg, Lancaster County, Pennsylvania.The museum is located on the east side of Strasburg along Pennsylvania Route 741...

 from 1979. While in operation, it had Strasburg Railroad lettering on both cab sides below the number.

Railroad Museum of Pennsylvania

Survivor D16sb #1223 is now a restored static exhibit at the Railroad Museum of Pennsylvania
Railroad Museum of Pennsylvania
The Railroad Museum of Pennsylvania is a railroad museum in Strasburg, Lancaster County, Pennsylvania.The museum is located on the east side of Strasburg along Pennsylvania Route 741...

, near Strasburg and the Strasburg Rail Road on which it operated for many years.
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