4 T 1 4 3

Duplex locomotive cycle arrangement

4-4-4-iv

Forepart of locomotive at left

The Baltimore & Ohio Railroad'south #5600 George H. Emerson.

Equivalent classifications UIC grade 2'BB2' French class 2222 Turkish class 2424 Swiss class 4/8 Russian class ii-2-ii-2

Beginning known tender engine version First apply May 1937 Country United States Locomotive B&O Class N-1 Railway Baltimore and Ohio Railroad Designer Baltimore and Ohio Railroad Architect Mountain Clare Shops Benefits Decreased wheelbase Drawbacks Premature cylinder clothing, cylinder clogging and restricted firebox size

First known "True type" version Showtime utilise April 1942 Country U.s. Locomotive PRR grade T1 Railway Pennsylvania Railroad Designer Ralph P. Johnson Raymond Loewy Builder Baldwin Locomotive Works Altoona Works Evolved from 4-viii-4 Benefits Ameliorate high speed performance Drawbacks Wheel slip

A 4-4-iv-4 steam locomotive, in the Whyte notation for describing locomotive wheel arrangements, has a iv-wheel leading truck, 2 sets of four driving wheels, and a iv-bike trailing truck. While it would be possible to make an articulated locomotive of this arrangement, the only iv-4-4-4s ever built were duplex locomotives—with two sets of cylinders driving two sets of driven wheels in one rigid frame, essentially a 4-8-4 with divided drive.

Usage [edit]

Item, showing the rearward cylinders and gear of the sole N-1.

The first locomotive built with this arrangement was the Baltimore and Ohio Railroad'southward sole class Northward-ane #5600 George H. Emerson, synthetic at the B&O's own Mount Clare Shops in May 1937. To reduce the fixed wheelbase, this locomotive had the two sets of cylinders at opposite ends, so that the rear pair were abreast the firebox. This proved to be a poor design, as it restricted the firebox size and exposed the cylinders to grit and dirt, causing premature wear. The locomotive was not considered successful enough to indistinguishable. The sole Northward-1 was retired in 1943 and scrapped in 1950.^[ane]

The next locomotives to utilise the four-iv-4-4 arrangement were the Pennsylvania Railroad's 52 class T1 locomotives (although the unmarried class S1 was originally intended to be a 4-4-4-4, it was later changed to 6-4-4-6 due to increased weight). These had the cylinders in forepart of the wheels they drove, so that the rear pair were between the ii sets of drivers. These locomotives were impressive performers but suffered from wheelslip and astringent reliability problems, and did not concluding long in service. ^[two] The two prototypes, #6110 and #6111, were synthetic at the Baldwin Locomotive Works in Apr 1942. The mechanical design work had been undertaken by Baldwin's chief engineer Ralph P. Johnson, while the streamlining was the handiwork of industrial designer Raymond Loewy.^{[ii] [three]} Both locomotives showed fantastic performance in examination trials, leading to the structure of 50 further examples. Numbers 5500 through 5524 would be constructed at the PRR's Altoona Works while 5525 through 5549 would be synthetic at Baldwin. As performance connected, bug arose. The T1 class was known for violent uncontrollable wheel sideslip equally well as performance and maintenance issues caused by the Franklin oscillating-cam Poppet valves.^[iv] The PRR did show interest in trying to solve these problems such as replacing the original poppets on #5500 with easier to maintain Franklin rotary-cam poppet valves and refitting #5547 with Walschaerts valve gears reclassifying the latter engine as a "T1a".^[4]

In the finish, the PRR decided to finish development of the T1 form, replacing all examples by the mid-1950s with diesel fuel units. All members of the class were scrapped. Information technology is very likely the T1 may have had many of its shortcomings solved had the PRR not retired the short-lived class so shortly.^[four] During its short service life, the T1 was rumored to have operated at higher speeds than the steam speed record set by the London and North Eastern Railway's Mallard, but the claims could not exist officially verified.^[5]

Several bush tramway engine types were built with this bike arrangement. These were known every bit "xvi-Wheelers". 2 notable builders were J. Johnson and Sons Ltd, Invercargill, and A & M Price, Thames, New Zealand.

Currently, but one locomotive of the four-4-4-iv arrangement is being constructed. When finished, PRR 5550 will be the 53rd and simply surviving case of the PRR T1 grade rather than a replica. Furthermore, the new build T1 is expected to implement some design improvements to help aid in solving problems encountered by the original 52. The estimated date of projection completion is currently set around the yr 2030.^[vi] As of November 4th 2019, the project is 34.1% complete with an estimated total cost of Us $7,000,000.^[7]

References [edit]

1. ^ Reed, Brian (June 1972). Pennsylvania Duplexii. Loco Profile 24. Windsor, Berkshire: Profile Publications Limited. pp. 266–267.
2. ^ ^{a b} Staufer 1962, p. 217.
3. ^ Staufer 1962, p. 225.
4. ^ ^{a b c} Staufer 1962, p. 218.
5. ^ "Railway Vehicle Information Sheet - 1975-7007 - Mallard" (PDF). National Railway Museum Official Website (PDF File). York England: National Railway Museum. p. iii. Archived (PDF) from the original on 31 October 2017. Retrieved nine May 2017.
6. ^ "FAQ Section - The T1 Trust". The Pennsylvania Railroad T1 Steam Locomotive Trust. 2016. Retrieved 23 Apr 2017.
7. ^ "5550 Tender Preservation Fund". prrt1steamlocomotivetrust.org. Pottstown, Pennsylvania, USA: Pennsylvania Railroad T1 Steam Locomotive Trust (published August 2017). 2017-08-21. Retrieved 2017-08-21 .

Further reading [edit]

• Staufer, Alvin (1962). Pennsy Power. Staufer. pp. 216–225. LOC 62-20872.

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Source: https://en.wikipedia.org/wiki/4-4-4-4

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