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differentials since manufacturers will often have a slightly lower ratio in the front vs. the rear to help with control (such as a 3.55:1 in the rear differential and a 3.54:1 in the front differential). If the transfer case did not make up the difference between the two different rates of rotation, binding would occur and the transfer case could become damaged. This is also why a transfer case that is not designed for on-road use will cause problems with
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20:
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for off-road use. Low range gears are engaged with a shifter or electronic switch. In many transfer cases, this shifter is the same as the one that selects 2WD or 4WD operation. Low range gears allow the vehicle to drive at much slower speeds while still operating within the usable power band / RPM
80:
and sends it to both the front and rear axles, or just one (usually the rear.) This can be done with gears, hydraulics, or chain drive. On some vehicles, such as four-wheel-drive trucks or vehicles intended for off-road use, this feature is controlled by the driver. The driver can put the transfer
234:
A divorced or independent transfer case is completely separate from the transmission. It is located further down the driveline than a married transfer case and connected to the transmission output shaft by a short driveshaft. Independent transfer cases are used on very long wheelbase vehicles, such
217:
Transfer cases are also classified as either "divorced"/independent or "married". Married transfer cases are bolted directly to the transmission, usually between the transmission's output shaft and the rear or main driveshaft. Sometimes a married transfer case is an integral part of the transmission
269:
Electronic Shift On-the-Fly (ESOF) transfer cases have a dash-mounted selector switch or buttons with front sealed automatic locking axle hubs or drive flanges. Unlike the manual transfer case, this system has a transfer case motor. To engage the four-wheel-drive system the vehicle must be moving
127:
acts on a given axle. This is necessary because the front and rear tires never turn at the same speed. Different rates of tire rotation are generally due to different tire diameters (since the front and rear tires inevitably wear at different rates) and different gear ratios in the front and rear
172:
four-wheel-drive off-road vehicles such as trucks and some specialty military vehicles generally allow the driver to select 2WD or 4WD, as well as high or low gear ranges. Automated versions used in sports cars and performance sedans are usually "transparent" to the driver; there is no shifter or
186:
There are two different types of internal power-transfer mechanisms found in most transfer cases. Gear-driven transfer cases use sets of gears to drive either the front or both the front and rear driveshafts. These are generally strong, heavy units that are used in large trucks, but there are
252:
or two manual front axle hub selectors of "LOCK" and "UNLOCK" or "FREE". To engage the four-wheel-drive system the vehicle must be moving at a low speed. The speed at which 4x4 can be engaged depends on the vehicle. This is only for the four-wheel-drive
112:
range of the engine. This also increases the torque available at the axles. Low-range gears are used for very inclement road conditions, towing a heavy load slowly, driving on rough, unimproved roads slowly, and extreme off-road maneuvers such as
195:
Chain-driven transfer cases use a chain to drive most often only one axle but can drive both axles. Chain-driven transfer cases are quieter and lighter than gear-driven ones. They are used in vehicles such as compact trucks, full-size trucks,
119:
The transfer case may require stopping entirely to engage four-wheel drive (or just low-range 4WD), slowing to a designated speed to engage or disengage an extra axle, or may permit full "shift-on-the-fly" engagement of high-range 4WD at any
146:
A part-/full-time hybrid transfer case enables a vehicle to operate in two-wheel drive, full-time four-wheel drive (with the center differential open) and part-time four-wheel drive (with the center diff locked) in both high- and
100:(AWD) sports cars, have transfer cases that are not selectable, known as "full-time". Such a transfer case is permanently "locked" into AWD mode. In recent decades hybrids have been developed that share properties of each.
63:
to mechanically deliver motive power. The transfer case also synchronizes the difference between the rotation of the front and rear wheels (only high-speed 4wd-Awd systems), and may contain one or more sets of
204:. Some off-road driving enthusiasts modify their vehicles to use gear-driven transfer cases, accepting the additional weight and noise to gain the extra strength they generally provide.
159:
tractor for selecting between 2WD and 4WD (left) and high and low gear ranges (right) are connected to the transfer case . The transfer case is currently in high-range, rear-wheel-drive.
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as commercial trucks or military trucks. This setup is also optimal for modified 4x4 because it's easier to change engine and transmissions, preserving the original 4WD system.
116:. This feature is often absent on all-wheel-drive cars. Some very large vehicles, such as heavy equipment or military trucks, may have more than one set of low-range gears.
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Transfer cases that are designed to allow for normal road use synchronize the difference between the rotation of the front and rear wheels, in much the same way the
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Manual Shift On-the-Fly transfer cases have a selector lever on the driver's side floor transmission hump and may also have either two sealed automatic front axle
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A transfer case that allows alternating between 2-wheel drive and 4-wheel drive modes but lacks a center differential for coordinating axle speeds is known as "
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setting, the vehicle must be stopped and the transmission must be shifted to neutral, then the four-wheel-drive low can be selected.
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setting, the vehicle must be stopped and the transmission must be shifted to neutral, then the four-wheel-drive low can be selected.
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ability to force both wheels of an axle to turn simultaneously by locking them together, only between axles instead of wheels.
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at a lower speed. The speed at which 4x4 can be engaged depends on the vehicle. This is only for the four-wheel-drive
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Most traditional transfer cases designed for off-road include the ability to mechanically lock the front and rear
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case into either "two-wheel-drive" or "four-wheel-drive" mode. This was traditionally accomplished by means of a
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Transfer cases also perform other functions. Some are common to all types, others vary by type:
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and the two components share the same housing or "case", as is commonly found on recent
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The transfer gearbox (a secondary transmission system) receives power from the
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to evenly distribute engine torque between them. This is similar to the
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currently several gear drive cases in production for passenger cars.
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107:The transfer case may contain one or more sets of
27:transfer case. Part-time/Manual, shift on the fly
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16:Drivetrain used in four-wheel drive vehicles
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257:setting. To engage the four-wheel-drive
274:setting. To engage the four-wheel-drive
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370:"Transfer case differential action"
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530:Continuously variable transmission
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385:Transfer case differential action
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43:of a motor vehicle to the driven
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344:Hardin, Drew (March 1, 2002).
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39:that transfers power from the
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565:Automated manual transmission
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304:Jeep four-wheel-drive systems
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7:
640:Semi-automatic transmission
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477:Internal combustion engine
289:AMC and Jeep transmissions
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132:if driven on dry pavement.
96:". Some vehicles, such as
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776:Hybrid vehicle drivetrain
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665:Transmission control unit
605:Limited-slip differential
570:Electrorheological clutch
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346:"How Transfer Cases Work"
555:Dual-clutch transmission
239:Transfer case shift type
222:products and some other
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840:Four-wheel drive layout
525:Constant-velocity joint
314:Mitsubishi Super Select
168:Transfer cases used on
85:, similar to that in a
505:Automatic transmission
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28:
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22:
610:Locking differential
545:Direct-shift gearbox
230:Divorced/independent
25:231 New Process Gear
635:Preselector gearbox
615:Manual transmission
141:differential lock's
87:manual transmission
68:for off-road use.
35:is an intermediate
835:Vehicle technology
781:Electric generator
686:Wheel hub assembly
309:List of auto parts
161:
29:
822:
821:
575:Epicyclic gearing
444:Automotive engine
847:
812:
811:
802:
679:Wheels and tires
650:Torque converter
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372:. Archived from
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319:New Venture Gear
155:The levers on a
130:driveline windup
49:four-wheel-drive
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109:low range gears
98:all-wheel-drive
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66:low range gears
53:all-wheel-drive
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376:on 2007-12-25
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59:, it employs
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33:transfer case
26:
21:
723:Racing slick
660:Transfer box
630:Park-by-wire
625:Parking pawl
540:Differential
515:Direct-drive
497:Transmission
487:Steam engine
432:Part of the
431:
378:. Retrieved
374:the original
364:
353:. Retrieved
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275:
271:
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258:
254:
250:locking hubs
247:
233:
216:
208:Housing type
194:
191:Chain-driven
185:
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137:drive shafts
125:differential
114:rockcrawling
102:
91:
78:transmission
75:
61:drive shafts
41:transmission
32:
30:
23:Inside of a
701:Alloy wheel
560:Drive wheel
550:Drive shaft
510:Chain drive
182:Gear-driven
177:Drive types
170:"part-time"
147:low-ranges.
829:Categories
786:Alternator
434:Automobile
423:Powertrain
380:2011-02-22
355:2024-03-30
326:References
57:drivetrain
655:Transaxle
620:Manumatic
590:Gearshift
462:Fuel cell
94:part-time
72:Functions
814:Category
753:Tubeless
738:Run-flat
718:Off-road
535:Coupling
457:Electric
299:Gear box
282:See also
265:E.S.O.F.
244:M.S.O.F.
213:Married
83:shifter
37:gearbox
804:Portal
764:Hybrid
728:Radial
706:Hubcap
520:Clutch
467:Hybrid
436:series
294:Clutch
226:cars.
220:Subaru
200:, and
157:Kubota
120:speed.
748:Spare
691:Wheel
595:Giubo
198:Jeeps
164:Types
45:axles
743:Snow
733:Rain
713:Tire
272:high
255:high
202:SUVs
696:Rim
276:low
259:low
47:of
831::
348:.
334:^
51:,
31:A
473:)
469:(
415:e
408:t
401:v
383:.
358:.
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