The Pennsylvania Railroad 's class FF1 was an American electric locomotive , a prototype numbered #3931 and nicknamed "Big Liz". It was built in 1917 to haul freight trains across the Allegheny Mountains where the PRR planned to electrify. "Big Liz" proved workable but too powerful for the freight cars of the time with its 4,600 hp (3,400 kW) and 140,000 lbf (620 kN ) of tractive effort. Pulling the train it regularly snapped couplers and when moved to the rear as a pusher its force was sufficient to pop cars in the middle of the train off the tracks.
15-403: It had a 2-6-6-2 wheel arrangement in two half- frames , connected in the center. Each frame had a pair of three-phase AC induction motors driving a jackshaft through gearing and a spring drive; side rods then drove the wheels. The jackshafts can be mistaken for an additional fourth axle but the "wheels" are cogwheels to transfer power from the motors to the jackshaft. Three-phase power for
30-468: A cowl unit is provided by the frame of the locomotive, rather than in the body as with a cab unit. This allows manufacturers to cheaply and easily create full-width locomotives from their hood unit designs by simply adding cowling. Cowl units were first introduced as a special order from the Santa Fe, which wanted a sleeker design for its passenger equipped hood units. Although the first cowl units (such as
45-513: A frame structure of some kind. The frame may in turn be supported by axles directly attached to it, or it may be mounted on bogies ( UK ) / trucks ( US ), or a combination of the two. The bogies in turn will have frames of their own. Three main types of frame on steam locomotives may be distinguished: These used steel plates about 1–2 in (25.4–50.8 mm) thick. They were mainly used in Britain and continental Europe. On most locomotives,
60-617: A single load-bearing assembly. They were first used on the Bury Bar Frame locomotive during the 1830s, and were widely used in nineteenth century American locomotives (including those exported to Australia and New Zealand; see Vogel railways ). Cast steel locomotive beds were developed in the latter years of steam locomotive design in the United States, from where they were also exported to Britain and Australia. An articulated locomotive with no fixed wheels (i.e. excluding
75-408: Is a stub . You can help Misplaced Pages by expanding it . Cab unit In North American railroad terminology , a cab unit is a railroad locomotive with its own cab and controls. "Carbody unit" is a related term, which may be either a cabless booster unit controlled from a linked cab unit, or a cab unit that contains its own controls. With both body styles, a bridge-truss design framework
90-435: Is a stub . You can help Misplaced Pages by expanding it . This United States train or rolling stock-related article is a stub . You can help Misplaced Pages by expanding it . 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
105-447: Is still popular elsewhere, but North American locomotives nowadays are overwhelmingly hood units —with a strong frame beneath the superstructure that carries all the load, and bodywork made of removable panels for easy maintenance. Fully enclosed locomotives are used in some limited applications, mostly for passenger trains . These tend to be cowl units , in which the body is not load-bearing. This locomotive-related article
120-454: Is used to make the body a structural element of the locomotive. The body extends the full width and length of the locomotive. The service walkways are inside the body. Carbody units, gaining rigidity from the body trusswork, require less structural weight to achieve rigidity than do locomotives with non-structural bodies. For that reason, carbody construction was favored to increase the power-to-weight ratio for early diesel locomotives, before
135-731: The EMD FP45 and the GE U30CG ) were meant for passenger service, EMD would later offer freight-only derivatives starting with the F45 . Cab units were not generally used in Great Britain. The traditional makers continued to use heavyweight frames and cowl units instead. The LMS twins 10000 and 10001 used the design and later locomotive types such as the British Rail Class 37 , and British Rail Class 40 utilised cab units but
150-596: The Mallet locomotive but including other articulated steam locomotives , as well as most diesel and electric locomotives ) may have a separate frame beneath the superstructure, or the bodywork's internal structure may be load-bearing. Rarely is a true monocoque structure used. Diesel and electric locomotives with a traditional, full-width body, known as cab units in North America , tend to have their strength in an internal structure. This style of construction
165-468: The streamliner trains. A cab unit is a carbody unit with a driving cab (or crew compartment). Thus, a cab unit is also always an A unit (a locomotive with a cab). By contrast, a carbody unit can be either an A unit, or a B unit (a locomotive without a cab). A cowl unit is an adaptation of the hood unit design with a full-width body. Despite some visual similarities, cowl units are actually very different from cab units. All structural support on
SECTION 10
#1732798152349180-405: The 4 massive motors was supplied from the single phase overhead supply via a large rotary converter housed in the body of the locomotive. Combined rated output of the motors was 7,640 hp (5,700 kW), but the converter could only supply a short term 4,600 hp (3,400 kW ) or a continuous 4,000 hp (3,000 kW). With three-phase induction motors there was no way to control
195-547: The frames would be situated within the driving wheels ("inside frames"), but some classes of an early steam locomotive and diesel shunters were constructed with "outside frames". Some early designs were double framed where the frame consisted of plates both inside and outside the driving wheels. Others were sandwich frames where the frame was constructed of wood sandwiched between two metal plates. These are openwork girder structures built up from steel or iron bars which are usually 4–7 in (100–180 mm) thick, welded into
210-531: The power available with diesel technology was increased. Recent years have seen carbody construction revived in the quest for greater fuel efficiency with passenger locomotives. The full-width body gives a carbody cab unit poor rear visibility compared with a hood unit . For that reason, cab or carbody units are mostly used in situations where rear visibility is not important, such as power for through freight and passenger trains . Cab and carbody units are also more aerodynamic than hood units, and pulled many of
225-473: The speed of the motors; changing the wiring of the motor poles allowed for two speed settings, 10.3 and 20.6 mph (16.6 and 33.2 km/h), which were considered enough to drag heavy freight trains up and down steep grades . Its intended use as an Allegheny climber never realized and its power too much for the rolling stock in service at the time, Big Liz was sidelined until being cut up for scrap in 1940. This electric locomotive-related article
#348651