A 6×4 or six-by-four is a vehicle with three axles, with a drivetrain delivering power to wheels at the ends of two of them.[1] It is a form of four-wheel drive[2] but not one of all-wheel drive.
It is the most common form of drivetrain of semi-tractors[2] and heavy haul fixed-chassis cargo trucks in larger countries such as the United States and Australia; in Europe, 4×2 and 6×2 variants are more commonplace.
The First World War saw a great adoption of petrol-engined lorries, beginning to replace horse transport. These were almost all simple 4×2 chassis, often based on commercial lorries or buses. Only a handful of 4×4 vehicles existed and these were slow and lumbering, with complicated servicing needed to their steering axle.
Between the wars there was a great interest in the development of vehicles with better off-road performance, both for the military and for the growing oil exploration industry. More driven axles were needed, for better grip, but also a heavier load capacity which itself required an additional axle. This led to designs favouring the 6×4 layout and 4×4 was largely ignored at first, at least from the major truck makers.[3] Military 6×4 chassis were also easier to produce for civilian manufacturers, as they were more similar to chassis for the larger civilian market, often just with uprated components. A few aberrations of 6×6, 8×8 and even half-tracks were produced,[4] but these were mostly as gun tractors or recovery vehicles and were too complex and expensive for General Service trucks. The standard design became a 6×4 truck of 3 ton capacity,[5] along with larger trucks of 10 tons.[6]
Bogie suspensionedit
With six wheels, the off-road performance often relied on articulation between the axles, so as to keep all the wheels in contact with uneven ground. A standard lorry chassis with live axles suspended by semi-elliptic leaf springs was inadequate for military use.
A solution to this was a bogie suspension. This coupled two rear wheels to a rigid frame or bogie but allowed this to tilt. The bogie pivoted freely for much of its range, allowing a greater movement than was possible with springs.[i][7] One of the best-known heavy tractor units of World War II, the Scammell Pioneer used this bogie system.[8][9]
Supplementary axlesedit
TACR2 airfield fire engine
Nearly all 6×4 have an unpowered leading steering axle, with two driven rear axles. However some mass-produced 4×4[ii] vehicles have had their load-carrying capability increased by adding an additional, unpowered, rear axle.
The Carmichael Commando chassis, a stretched version of the Range Rover, was used for such extended 6×4 conversions in the 1970s and '80s. Some German conversions provided full 6×6 performance, but most were like the TACR2 and just 6×4. This gave a vehicle suitable for airfield emergency services; with fast performance on tarmac, useful off-road performance for crossing obstacles, increased load capacity and a much cheaper price than dedicated 6×6 vehicles.
^These have been mostly AWD vehicles with permanent 4WD and good road performance rather than the selectable 4WD used more widely for earlier off-road vehicles.
Referencesedit
^"International ProStar ES Class 8 truck". Retrieved 2024-04-29.
^ ab(PDF) (Report). Archived from the original (PDF) on 2015-07-07. A typical three axle Class 8 tractor today is equipped with two rear drive axles ("live" tandem) and is commonly referred to as a 6 X 4 configuration meaning that it has four-wheel drive capability.
^Freathy, Les (2012). British Military Trucks of World War Two. Erlangen: Tankograd Publishing. pp. 11–14. ISBN978-3-936519-29-7.
^Georgano, Nick (1997). "4: Cross Country, Military and Export, The Pioneer and its Descendants". Scammell: The Load Movers From Watford. Roundoak Publishing. pp. 36–38. ISBN1 871565 26 X.
This article about an automotive technology is a stub. You can help Wikipedia by expanding it.
four, vehicle, with, three, axles, with, drivetrain, delivering, power, wheels, ends, them, form, four, wheel, drive, wheel, drive, typical, american, tractor, unit, most, common, form, drivetrain, semi, tractors, heavy, haul, fixed, chassis, cargo, trucks, la. A 6 4 or six by four is a vehicle with three axles with a drivetrain delivering power to wheels at the ends of two of them 1 It is a form of four wheel drive 2 but not one of all wheel drive Typical American 6 4 tractor unit It is the most common form of drivetrain of semi tractors 2 and heavy haul fixed chassis cargo trucks in larger countries such as the United States and Australia in Europe 4 2 and 6 2 variants are more commonplace Contents 1 Off road vehicles 1 1 Bogie suspension 2 Supplementary axles 3 See also 4 Notes 5 ReferencesOff road vehicles edit nbsp 1937 military lorry off road The First World War saw a great adoption of petrol engined lorries beginning to replace horse transport These were almost all simple 4 2 chassis often based on commercial lorries or buses Only a handful of 4 4 vehicles existed and these were slow and lumbering with complicated servicing needed to their steering axle Between the wars there was a great interest in the development of vehicles with better off road performance both for the military and for the growing oil exploration industry More driven axles were needed for better grip but also a heavier load capacity which itself required an additional axle This led to designs favouring the 6 4 layout and 4 4 was largely ignored at first at least from the major truck makers 3 Military 6 4 chassis were also easier to produce for civilian manufacturers as they were more similar to chassis for the larger civilian market often just with uprated components A few aberrations of 6 6 8 8 and even half tracks were produced 4 but these were mostly as gun tractors or recovery vehicles and were too complex and expensive for General Service trucks The standard design became a 6 4 truck of 3 ton capacity 5 along with larger trucks of 10 tons 6 Bogie suspension edit With six wheels the off road performance often relied on articulation between the axles so as to keep all the wheels in contact with uneven ground A standard lorry chassis with live axles suspended by semi elliptic leaf springs was inadequate for military use A solution to this was a bogie suspension This coupled two rear wheels to a rigid frame or bogie but allowed this to tilt The bogie pivoted freely for much of its range allowing a greater movement than was possible with springs i 7 One of the best known heavy tractor units of World War II the Scammell Pioneer used this bogie system 8 9 Supplementary axles edit nbsp TACR2 airfield fire engine Nearly all 6 4 have an unpowered leading steering axle with two driven rear axles However some mass produced 4 4 ii vehicles have had their load carrying capability increased by adding an additional unpowered rear axle The Carmichael Commando chassis a stretched version of the Range Rover was used for such extended 6 4 conversions in the 1970s and 80s Some German conversions provided full 6 6 performance but most were like the TACR2 and just 6 4 This gave a vehicle suitable for airfield emergency services with fast performance on tarmac useful off road performance for crossing obstacles increased load capacity and a much cheaper price than dedicated 6 6 vehicles See also editFour wheel drive Six wheel driveNotes edit Horstmann suspension did something similar for tracked vehicles and tanks at around the same time These have been mostly AWD vehicles with permanent 4WD and good road performance rather than the selectable 4WD used more widely for earlier off road vehicles References edit International ProStar ES Class 8 truck Retrieved 2024 04 29 a b NACFE North American Council for Freight Efficiency Executive Report 6x2 Dead Axle Tractors PDF Report Archived from the original PDF on 2015 07 07 A typical three axle Class 8 tractor today is equipped with two rear drive axles live tandem and is commonly referred to as a 6 X 4 configuration meaning that it has four wheel drive capability Freathy Les 2012 British Military Trucks of World War Two Erlangen Tankograd Publishing pp 11 14 ISBN 978 3 936519 29 7 Freathy 2012 p 12 Freathy 2012 pp 11 14 Freathy 2012 pp 36 37 Albion CX Tuck Bob 1987 The Supertrucks of Scammell Motor Racing Publications pp 16 17 ISBN 0 948358 01 7 Tuck 1987 pp 21 22 Georgano Nick 1997 4 Cross Country Military and Export The Pioneer and its Descendants Scammell The Load Movers From Watford Roundoak Publishing pp 36 38 ISBN 1 871565 26 X nbsp This article about an automotive technology is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title 6 4 amp oldid 1221395158, wikipedia, wiki, book, books, library,
