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Overdrive in automatic cars

Discussion in 'Tech, Gadgets & Science Forum' started by Kimori88, Apr 27, 2011.

  1. K

    Kimori88 Member

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    Apr 27, 2011
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    Hello GREAT THINKERS!
    Nimekutana na huu ubishani kuwa ni wakati gani Over drive facility inatumika katika gari? Je ikiwa off inaonekana vipi kwenye dashboard? Thanks
     
  2. Dingswayo

    Dingswayo JF-Expert Member

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    Kwa kawaida magari yanatumia gear nne, overdrive inaweza kuwa ya 5, au kwa magari mengine 6. Overdrive ikiwa off ina maana kuwa gari litakwenda kwa kutumia gear 4 tu. Overdrive inatumika mara nyingi ukiwa kwenye mwendo mkali kwa mfano kwenye highways. Ukiwa mjini mara nyingi mtu unatumia mpaka gear ya 4 tu. Hakikisha ukiwa kwenye highway, button ya overdrive iwe 'on'.
     
  3. Inkoskaz

    Inkoskaz JF-Expert Member

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    OD inatakiwa kuwa on(button pressed) katika hali ya kawaida ila ukihitaji ku-cruise power zaidi ndo unadisengage..normaly the dashboard indicator should be off
     
  4. wende

    wende JF-Expert Member

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    No matter upo H/way or on town,You can engage/press and keep OD down throughout the time,wala haina taabu coz AUTO Vehicles ni self controlled as you acceralate!
    Ikiwa hujapress OD down pale ktk gear selector,utaona neno "OFF" kwenye dashoard. Ukigandamiza OD button,basi OFF inaishia na utakuwa unaendesha gari yako ktk OD mode!
     
  5. wende

    wende JF-Expert Member

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    ....confusing!
     
  6. itnojec

    itnojec JF-Expert Member

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    really,
     
  7. kikahe

    kikahe JF-Expert Member

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    Mimi ninachojua ni kuwa, kama kwenye dashboard lile neno O/D off linaonekana ni kuwa Overdrive iko OFF na kama halionekani ni kuwa O/D iko ON. Na mostly inatumiaka ukiwa kwenye highway ili iweze kumaliza gears zote ila ikiwa off inakuwa na limit ya Gears. BUT I stand to be corrected
     
  8. CAMARADERIE

    CAMARADERIE JF-Expert Member

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    Magari mengi ya automatic gear from 2000 hayana hii kitu........ni old technology

    Overdrive is a term used to describe a mechanism that allows an automobile to cruise at sustained speed with reduced engine speed, leading to better fuel consumption, lower noise and lower wear. Use of the term is confused, as it is applied to several different, but related, meanings.

    The most fundamental meaning is that of an overall gear ratio between engine and wheels, such that the car is now over-geared and can no longer reach its potential top speed, i.e. the car could travel faster if it were in a lower gear, with the engine turning more quickly. The purpose of such a gear may not be immediately obvious. The power produced by an engine increases with the engine's speed to a maximum, then falls away. The point of maximum power is somewhat slower than the absolute maximum speed to which the engine is limited, the "redline" speed. A car's speed is limited by the power available to drive it against air resistanceĀ—so the maximum possible speed is obtained at the engine's point of maximum power, or power peak, and the gear ratio necessary to achieve this will be the single ratio between these two speeds.

    As the power needed increases dramatically at high speeds, most cars will be capable of achieving a fast cruising speed slightly less than their maximum, but with far less power being required. This power is available well below the engine's power peak and so the ideal cruising gear is an overdrive gear, a ratio higher than that for absolute top speed.

    With the early development of cars and the almost universal rear-wheel drive layout, the final drive (i.e. rear axle) ratio for fast cars was chosen to give the ratio for maximum speed. The gearbox was designed so that, for efficiency, the fastest ratio would be a 'direct-drive' or 'straight-through' 1:1 ratio, avoiding frictional losses in the gears. Achieving an overdriven ratio for cruising thus required a gearbox ratio even higher than this, i.e. the gearbox output shaft rotating faster than the original engine speed. The propeller shaft linking gearbox and rear axle is thus overdriven, and a transmission capable of doing this became termed an "overdrive" transmission.

    The device for achieving an overdrive transmission was usually a small separate gearbox, attached to the rear of the main gearbox and controlled by its own shift lever.These were often an optional extra on some models of the same car.As popular cars became faster relative to legal limits and fuel costs became more important, particularly after the 1973 oil crisis, the use of 5-speed gearboxes became more common in mass-market cars. These had a direct fourth speed with an overdrive top gear, replacing the need for the separate overdrive gearbox.

    With the popularity of front wheel drive cars, the separate gearbox and final drive have merged into a single transaxle. There is no longer a propeller shaft and so one meaning of "overdrive" can no longer be applied. However the fundamental meaning, that of an overall ratio higher than the ratio for maximum speed, still applies. Although the deliberate labelling of an overdrive is now rare, the underlying feature is now found across all cars.
     
  9. Sumbalawinyo

    Sumbalawinyo JF-Expert Member

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    naona maluweluwe tu. Bora magari yetu manual
     
  10. Inkoskaz

    Inkoskaz JF-Expert Member

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    wende angalia maelezo haya ya wikipedia aliyotoa Camaradiere japo mimi nilieleza kwa kifupi
     
  11. Mtoka Mbali

    Mtoka Mbali JF-Expert Member

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    Ndivyo sivyo, yaani nje ndani, yaani upside down, yaani mawazo yako yageuze yawe kinyume na hiyo ndokawaida. Kama huwa unafanya hivyo basi unatakiwa ufanye the other way round.
     
  12. Albedo

    Albedo JF-Expert Member

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  13. wende

    wende JF-Expert Member

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    Daaa,haya bana....sure urs was very brief. Kwa apo sawa!
     
  14. C

    Caroline Danzi JF-Expert Member

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    Sijawahi kutumia OD, sidhani kama naweza itumia kwa sababu sijawahi kuwa na haraka kwenye maisha yangu. Huwa naenda na muda pale inanilazimu. Nikiweka D naenda mpaka muda wa P ufike.

    Haraka mara nyingi siyo nzuri, ninachoweza kusema muwe na uvumilivu.
     
  15. Revolutionary

    Revolutionary JF-Expert Member

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    Tusitake kuwa mainjinia wa magari, ni kwamba kwenye mizunguko ya kawaida weka overdrive on, isipokua kwenye vilima vikali! Tena inasaidia kupunguza fuel consumption.
     
  16. O

    One Man Army JF-Expert Member

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    heshima mbele wakuu.nilikua nahitaji kujua kuhusu matumizi ya overdrive na je ni kweli gari ukiweka overdrive hutumia mafuta mengi?please kwa kama unauelewa na hili jambo utufahamishe..
     
  17. M

    Mkwe21 JF-Expert Member

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    Apr 25, 2012
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    General
    Nadhani ile indication ya
    "overdrive" Huwa inawasumbua watu wengi Kuielewa!! Kwa Kawaida kama ile taa Haiwaki, Normal condition ndio Inakuwa gari Kialisia ipo kwenye Overdrive!! Na ukiwasha button ya overdrive inakuja message inasema "overdrive off!!" Means muda huo hauko kwenye overdrive na taa inakuwa inaonyesha kwenye Dashboard!! Na always kwenye dashboard kukiwa na any lighting ikiwa "on" hii inamaanisha something is not Normal!!

    Overdrive
    Overdrive maana yake ni kuwa katika uendeshaji wa gari unakuwa umeruhusu kwenye Mwendo fulani (Say 100km/hr and above) mzunguko wa Engine Unakuwa mdogo kuliko Mzunguko wa Gearbox!! Ikimaanisha mzunguko mmoja wa engine ni sawa na mizunguko miwili ya Gearbox (Mfano). kwa kawaida gari ikianza kuacellarate (Mwendo) Huwa mzunguko wa Engine ni Mkubwa kuliko Mzunguko wa Gearbox, na inapofika gear no 4 (Vehicle speed) Engine speed inakuwa sawa na Gearbox speed!! Then kama gari inakuwa kwenye Overdrive Then Unaweza kuaccelarate hadi gear namba 5 na 6 ambazo hizi ni overspeed!! Kumaanisha mzunguko wa Gearbox ni mkubwa kuliko mzunguko wa Engine!! - Note Engine is the source of Motion so you are over the speed of Engine!!

    Overdrive "off"
    Hii inamaanisha imeilazimisha gari yako iende hadi Gear no 4 bila kuiruhusu gear no 5 na 6 (Kwa baadhi ya Magari) Hivyo kitendo hicho kinafanya gari kutoa mlio Mkali kwani Unapokuwa kwenye gear no 4 na mwendo wa 120km/h unakuwa unailazimisha engine kuzunguka sana na Hivyo unaweza kuwa na revolution ya up to 4.5 rpm to 5 rpm hence more consumption of fuel hence more energy!!!

    Remarks on Overdrive "off"

    Hii inashauriwa Kutumiwa kama kuna sehemu unahitaji kulipa gari Nguvu Kubwa kwa kipindi Kifupi i.e Kama Kupanda Mlima Kitonga kwa speed Kubwa na si vinginevyo!!

    Kama una swali Jingine Uliza!!
     
  18. Goodrich

    Goodrich JF-Expert Member

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    Overdrive (OD) is a term used to describe a mechanism that allows an automobile to cruise at sustained speed with reduced engine RPM, leading to better fuel economy, lower noise and lower wear.[SUP][1][/SUP] Use of the term is confused, as it is applied to several different, but related, meanings.[SUP][1][/SUP] The most fundamental meaning is that of an overall gear ratio between engine and wheels, such that the car is now over-geared and can no longer reach its potential top speed, i.e. the car could travel faster if it were in a lower gear, with the engine turning more quickly. In some cases this implies a second definition is also true, that the gearbox output driveshaft is rotating faster than the original engine RPM. This later definition was common in the past, but many cars no longer have a driveshaft and it is not technically correct.[SUP][1][/SUP]
    In the era of front-engine, rear-wheel drive layouts, the device for achieving an overdrive transmission was usually a small separate gearbox, attached to the rear of the main gearbox and controlled by its own shift lever or electrical actuation button. These were often an optional extra on some models of the same car. As popular cars became faster relative to legal limits and fuel costs became more important, particularly after the 1973 oil crisis, the use of 5-speed gearboxes became more common in mass-market cars, with the 5th gear being an overdrive, eliminating the need for a separate gearbox.[SUP][1][/SUP]
    With the popularity of front wheel drive cars, the separate gearbox and final drive have merged into a single transaxle. However the fundamental meaning, that of an overall ratio higher than the ratio for maximum speed, still applies.[SUP][1][/SUP] Although the deliberate labelling of an overdrive is now rare, the underlying feature is now found across all cars.
     
  19. Goodrich

    Goodrich JF-Expert Member

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    Excellent !!!
     
  20. k

    kifuruko Member

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    Hapo sina cha kuongeza, umefafanua vya kutosha. Big up!
     
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