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North
America, this type of cab can be useful in rigid trucks, but has little advantage in tractors and is rarely used. EU rules (introduction of EU Regulation No. 2019/1892) have been relaxed since September 2021 to allow for a longer cab, where the additional length is used to improve aerodynamics and vulnerable road user safety.
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four axles, but with all of them driven, and 10×8 units have five axles with the rear four usually driven and the front axle for steering. All five axles of 10×10 units are driven. The front two axles are usually both steer axles. The axle configurations are usually based on axle load legislation, and maximum
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The cab over engine or cab forward "flat face" has a flat nose cab with the driver sitting in front of the front axle. Widely used in the EU and Japan, this style has the advantages of good vision and maneuverability and shorter cab length, at the expense of driver safety in case of an accident. In
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on the driven axle. The 6×6 units have three axles, all can be driven, and 8×6 units have four axles, with either the rear three driven and the front axle not, or the front and rear-most two axles powered and an unpowered lifting center axle to spread the load when needed. The 8×8 units also have
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types. However, some manufacturers offer 4×4, 6×6, 8x4, 8×6, 8×8, 10×8, and 10×10 axle configurations. A 6×4 has three axles, normally an undriven front steer axle and the two rear axles driven. 6×4 units are more common in long-distance haulage in larger countries such as the United States and
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weight restrictions. With the loosening of length restrictions in 1982 this style had limited applications, and is no longer manufactured for the U.S. market. This style is still popular in
Australia and New Zealand where length restrictions apply and it is used to maximise the capacity of both
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Most tractor units are based on the chassis of a large truck (Class 8 in North
America) minus the cargo body, with shorter frames used for cabovers and day-cab tractors, and longer frames used for
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couplings are also found, particularly in dedicated exceptionally heavy-duty ballast tractors and as a means to connect intermediate fifth-wheel dollies for pulling multiple semi-trailers.
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A North
American style cab over engine "bull nose", largely obsolete, had a flat nose cab located higher over the engine, with the driver sitting above the front axle. This allowed a
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The conventional "dog nose" has an engine and hood over the front axle in front of the cab, as in most automobiles. This style is almost universal in North
America.
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still manufacture trucks in this style for this market. In
Australia both styles of cab over engine truck as well as conventionals are in common use.
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axle, which can also be driven. Most 6×2 units allow the undriven rear axle to be raised when lightly loaded, or running without a trailer, to save
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This article is about the power unit for hauling towed or trailered loads. For the vehicle used in agriculture or construction, see
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distributes a load across multiple axles while being more maneuverable than an equivalently sized rigid
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can be rapidly swapped between tractors, eliminating downtime while a trailer is unloaded or loaded.
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There have been three common cab configurations used in tractors, two are still widely used.
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load. These fall into two categories: heavy- and medium-duty military and commercial
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in a short tractor, and maximum wheelbase relative overall length, important for
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Heavier versions of tractor units, such as those used in heavy haulage and
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by fitting temporary ballast, which may require special permitting.
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single trailer and B double configurations, and
American companies
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632:"Freight Management and Operations: Bridge Formula Weights"
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8×8 Heavy
Equipment Transporter (HET) tractor pulling a 5-
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Tractors with three axles or more can have more than one
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657:"Freight Management and Operations: Size Regulations"
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679:"Guidelines on Maximum Weights…Criteria (EU)"
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179:which is a combination of a tractor unit and
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318:tractors, to accommodate the longer cabin.
270:for power, durability, and economy; several
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605:"Tractor Units Information UK Regulations"
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403:6×6 NBC detection vehicle near Baghdad
27:A truck designed to tow semi-trailers
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278:for maximum flexibility in gearing.
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659:. U.S. Department of Transportation
634:. U.S. Department of Transportation
431:Typical tractor unit versions from
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301:. Trailers containing differing
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152:semi-tractors used for hauling
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684:. Road Safety Authority. 2013
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263:Tractor units typically have
458:gross vehicle weight ratings
283:tractor–trailer combination
229:(not present in all trucks)
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18:Prime mover (tractor unit)
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734:Articulated vehicles
715:at Wikimedia Commons
609:www.truckpages.co.uk
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451:fees, and increase
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537:Semi-trailer truck
522:Gladhand connector
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210:semi-trailer
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465:road trains
447:wear, save
316:Sleeper cab
299:box trailer
295:bulk tipper
243:fifth wheel
218:compartment
94:tractor cab
78:ten-wheeler
74:prime mover
46:sleeper-cab
723:Categories
614:2024-02-22
591:References
527:Road train
238:fuel tanks
166:commercial
90:semi-lorry
86:semi-truck
70:power unit
66:lorry unit
62:truck unit
449:toll road
327:Cab Types
146:trailered
102:lorry cab
98:truck cab
42:Peterbilt
517:Cab over
479:See also
453:traction
441:steering
369:Kenworth
337:cab-over
274:; and a
246:coupling
191:Overview
158:off-road
688:25 June
638:25 June
552:Tractor
460:(BDM).
401:M93 Fox
309:Drawbar
233:air dam
227:sleeper
201:tractor
134:big rig
118:tractor
32:Tractor
729:Trucks
663:25 Jun
422:Europe
392:M1000
303:cargos
216:engine
682:(PDF)
564:Notes
547:Toter
409:axles
390:bogie
376:Axles
287:truck
272:axles
253:space
251:cargo
222:cabin
142:towed
126:lorry
122:truck
690:2013
665:2013
640:2013
445:tire
394:HETS
367:and
297:and
281:The
255:10.
130:semi
44:386
417:6×4
384:An
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231:6.
225:5.
220:4.
214:3.
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162:6×6
144:or
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136:or
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