Manual Transmissions
description
Transcript of Manual Transmissions
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Manual Transmissions
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Purpose To change the torque going to the drive wheels
Needed to start vehicle from a stand still
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Basic Theory Manually shifted Clutch disc rotates the input shaft Output shaft powers wheels
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Transaxle A differential and transmission in the same housing Common in four wheel drive vehicles Manual or automatic transmissions
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Parts Input shaft GearsSynchronizers Shift fork
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PartsGear shift leverOutput shaft Transmission case
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Input Shaft Driven by clutchTurns gears inside transmission
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Transmission gears Provides a means of changing output torque and speed
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Synchronizers Devices that help gears mesh into desired arrangement
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Shift fork Unit for moving gears in and out of arrangement
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Gear shift leverA lever that provides the driver with the ability to change the gear arrangement
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Output Shaft Shaft that transfers power from the transmission to the wheelsTransfers power to drive shaft in a rear wheel drive vehicle
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Transmission CaseHousing that encases transmission shafts, gears, and lubricant
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Gear RatioDefinition: the number of rotations a drive gear has to turn before the driven gear turns once
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Determining Gear Ratio
Found by dividing the number of teeth on the driven gear by the number of teeth on the drive wheel
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Gear Reduction A smaller gear drives a larger gear Increases torque and decreases the speed
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Over Drive Gear A large gear drives a smaller gear Torque is decreased and speed is increased
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Gear types There are two types of gears found in manual transmissions Spur gears Helical gears
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Spur Gears Teeth cut parallel to center shaft Not used for drive gears Used for gears that have to slide in and mesh with other gears Noisy
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Helical Gears Teeth cut out of parallel to drive shaft Used for constant drive components More efficient Quiet
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Gear back lash Small clearance between meshing gears Allows lubricant to flow between high friction gears Allows gears to expand during operation
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Lubricant Splash lubricant Gears fling lubricant around transmission Gear oil: 80W to 90W (always check owners manual)
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Transmission shafts Input shaft Counter shaft Reverse idler shaft Output shaft
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Input shaft (AKA clutch shaft)Transfers power from clutch to the counter shaft Splined on clutch side and a fixed gear on the transmission side Whenever clutch is turning the input shaft is turning
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Counter shaft (AKA cluster gear shaft)Holds counter shaft gears into mesh with the input shaft gear
Counter shaft does not turn
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Reverse idler shaft Small shaft that supports idler gear Reverse idler gear meshes with gears on both the input shaft and the counter shaft
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Output shaft (AKA Main shaft)Holds output gears and synchronizers Extends out of the transmission to power the drive wheels
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Shift forks Sits around synchronizer sleeves
Transfers movement from the gear shifter linkage to the synchronizers
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Problems Grinding sounds when shifting Worn gear change linkage Clutch grabbing Synchronizer gears grinding going into mesh
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Problems Transmission noise Roaring, rumbling, whirling sounds Low lubricant, metal contaminants
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Problems Difficulty shifting Problem with the linkage for the shifter mechanismClutch problems
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Problems Jump out of gear Worn clutch pilot bearing causes vibration and wobbling of the transmission input shaft. The vibration and wobbling shakes the synchronizers out of gear
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Problems Locked in gear Shifter assembly problems Broken drive gear teeth, bits stuck in gears