Cab forward

The term cab forward refers to various rail and road vehicle designs which place the driver's compartment substantially farther towards the front than is common practice.

Rail locomotives

In steam locomotive design, a cab forward design will typically have the driver's compartment placed immediately forward of the firebox at the very front of the engine while the fireman's station remains on the footplate behind the firebox (for obvious reasons). This type of design was widely, though not commonly, used throughout Europe in the first half of the 20th century, often in conjunction with an enclosed body design and/or streamlining.

Italy: Ferrovie dello Stato italiane (FS)

The state owned Italian FS had several cab forward locomotives, 4-6-0 types group 670, 671, 672 and 0-10-0 types 470. The 670 to 672 group engines had a 3 axle tender, the nickname was "mucca" (cow). The engines (construction year 1902, top speed 110 km/h) were used to haul passenger trains on the east coast line.

Southern Pacific

In contrast however, the best known example of the cab-forward design in the United States, the Southern Pacific Cab-Forward (also known as "Cab-in-fronts") placed the cab at the front by the simple expedient of turning the entire locomotive, minus the tender, by 180 degrees, an arrangement made possible by burning fuel oil instead of coal.

The cab forward design was widely used by the Southern Pacific Railroad, which developed it to deal with the peculiar problems of its routes. The 39 long tunnels and nearly convert|40|mi|km of snow sheds of the Sierra Nevada Mountains could funnel dangerous exhaust fumes back into the crew compartment of a conventional locomotive. After a number of crews nearly asphyxiated, someone had the idea of running his locomotive in reverse. This meant that the tender was leading the train, which introduced new problems. The tender blocked the view ahead and put crewmen on the wrong sides of the cab for seeing signals. The tenders were not designed to be pushed at the lead of the train, which limited speeds. Southern Pacific commissioned Baldwin Locomotive Works to build a prototype cab-forward locomotive, then ordered more before the prototype had even arrived.

All of the cab-forwards were oil-burning locomotives, which meant there was little trouble involved putting the tender at what would normally be the front of the locomotive. The oil and water tanks were pressurized so that both would flow normally even on uphill grades. Visibility from the cab was superb, such that one crewman could easily survey both sides of the track. There were concerns about what would happen to the crew in the event of a collision, and at least one fatal accident occurred on the Modoc Line when a moving locomotive struck a flat car. Turning the normal locomotive arrangement around also placed the crew well ahead of the exhaust fumes, insulating them from that hazard. One problematic aspect of the design, however, was the routing of the oil lines; because the firebox was located ahead of the driving wheels (instead of behind them, the usual practice), oil leaks could cause the wheels to slip. A nuisance under most conditions, it resulted in at least one fatal accident. This occurred in 1941 when a cab-forward with leaking steam and oil lines entered the tunnel at Santa Susana Pass near Los Angeles. The tunnel was on a grade, and as the slow-moving train ascended the tunnel, oil on the rails caused the wheels to slip and spin. The train slipped backwards and a coupler knuckle broke, separating the air line, causing an emergency brake application and stalling the train in a tunnel that was rapidly filling with exhaust fumes and steam. The oil dripping on the rails and ties then ignited beneath the engine cab, killing the crew.

No other North American railroad ordered cab-forward locomotives. Built to deal with difficult terrain, these remarkable locomotives became an easily recognizable symbol of the Southern Pacific. One example of the type, Southern Pacific 4294, is kept at the California State Railroad Museum in Sacramento, California. It is a 4-8-8-2 locomotive and is the only one to escape being scrapped.

Oliver Bulleid's ill-fated "Leader" is sometimes referred to as a cab-forward locomotive, but since it had a cab at each end like a typical modern electric locomotive this designation is at best misleading.

Road transport

Automobiles

The first modern mass produced, U.S. automobile design using the cab forward concept was the Pacer, introduced in 1975 by American Motors (AMC). [ [http://www.azsolo2.com/pylon_press/pp2003/pp200311.htm Driscoll, Mike. "The pylon points to: Mindi Cross", "The Pylon Press", November 2003] , retrieved on July 24, 2008.] [ [http://www.amcpacer.com/features/did-the-pacer-kill-amc.asp Stakes, Eddie. Response to the posting of Matt Crawford's "Why a Pacer?" essay, "Did the Pacer kill AMC?" undated] , retrieved on July 23, 2008.] [cite book | last = Peter | first = Eric | title = Automotive Atrocities: The Cars We Love to Hate | publisher = MotorBooks/MBI Publishing Company | date = 2004 | pages = 54 | isbn = 978-0760317877 ] The company did not call it "cab forward", but the Pacer's layout included wheels pushed to the corners (short overhangs), a relatively wide body, and A-pillars moved forward; the windshield was placed over part of the engine compartment. [ [http://www.okanaganracing.com/articles/markus/042006.htm "Tech Transfer" Okanagan Racing, April 2006] , retrieved on July 24, 2008.] The cab forward design allowed the passenger area to be much larger than in other similar sized automobiles. [ [http://www.american-motors.de/en/pacer/history/amc_pacer.pdf Mederle, Wolfgang A. "Chapter 1: History" "The American Motors Pacer", December 26, 2005] , retrieved on July 24, 2008.]

In automobile design, the term "cab forward" was used by Chrysler Corporation starting in 1992 to refer to their new styling and engineering features, similar to those seen on the AMC Pacer, which improved cornering and interior space [ [http://query.nytimes.com/gst/fullpage.html?res=9D00E5DD1039F932A25751C1A962958260 Taras, Jeffrey J. "Driving Smart; What's the Big Deal About 'Cab Forward' Cars?" The New York Times, December 11, 1994] , retrieved on July 24, 2008.] The passenger cabin was "pushed forward" so that the front wheelwell directly abutted the leading edge of the front doors, and the windshield extended forward near the front axle, while the rear wheels were shifted towards the back corners of the vehicle. Moving the wheels to the edges allowed designers to enlarge the interior while improving ride and cornering. Numerous models built from 1993 to 2004 on the Chrysler LH platform, the JA and JR platforms ("cloud cars"), and the PL platform (Neon), were specifically marketed as cab forward cars. Chrysler claimed to be the first to apply these features to a full-size car. [ [http://www.allpar.com/corporate/cab-forward.html "Chrysler Defines Cab-Forward and the Second-Generation LH Cars' Styling" allpar,com, undated] , retrieved on July 24, 2008.]

Commercial vehicles

In road vehicle design, Cab forward, also known as Cab-over, COE (Cab Over Engine), or forward control, is a body style of truck or van that has a vertical front or "flat face", with the cab sitting above the front axle. This truck configuration is currently common among European and Japanese truck manufacturers, because the laws governing overall vehicle lengths are strict and the body style allows longer trailers or a longer cargo area for the same overall length than a standard truck (with an engine compartment ahead of a conventional cabin). Better visibility and maneuverability in tight quarters, such as for city delivery, is a benefit of locating the truck's cab up front. Large trucks of this type are most often described as "cab over engine" (COE) or cab over models.

References

External links

* [http://www.skyrocket.de/locomotive/cabforward.htm A site with a good selection of photographs of cab-forward locomotives.]
* [http://www.steamlocomotive.com/cabforward/ Steam Locomotive.com's Southern Pacific Cab Forward article, including detailed specs.]