Manual Gearbox in Automatic Transmission

Manual transmission (also known as a manual gearbox; abbreviated as MT) is a multi-speed transmission where gear changes require the driver to select the gears by manually operating a gear stick and clutch (which is usually a foot pedal for cars, or a hand lever for motorcycles).

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Early automobiles used sliding mesh manual transmissions with up to three forward gear ratios. Since the 1950s, constant mesh manual transmissions have become increasingly commonplace and the number of forward ratios has increased to 5-speed and 6-speed manual transmissions for current vehicles.

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The alternative to a manual transmission is the automatic transmissions; common types of automatic transmissions are the hydraulic automatic transmission (AT), automated manual transmission (AMT), dual-clutch transmission (DCT), and the continuously variable transmission (CVT).

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A manual transmission requires the driver to operate the gear stick and clutch in order to change gears (unlike an automatic transmission or semi-automatic transmission, where one or both of these functions are automated). Most manual transmissions for cars allow the driver to select any gear ratio at any time, for example shifting from 2nd to 4th gear, or 5th to 3rd gear. However, sequential manual transmissions, which are commonly used in motorcycles and racing cars, only allow the driver to select the next-higher or next-lower gear.

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In a vehicle with a manual transmission, the flywheel is attached to the engine's crankshaft, therefore rotating at engine speed. A clutch sits between the flywheel and the transmission input shaft, controlling whether the transmission is connected to the engine (clutch engaged- the clutch pedal is not being pressed) or not connected to the engine (clutch disengaged- the clutch pedal is being pressed down). When the engine is running and the clutch is engaged (i.e., clutch pedal up), the flywheel spins the clutch plate and hence the transmission.

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The design of most manual transmissions for cars is that gear ratios are selected by locking selected gear pairs to the output shaft inside the transmission.

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Contemporary manual transmissions for cars typically use five or six forward gears ratios and one reverse gear, however, transmissions with between two and seven gears have been produced at times. Operating such transmissions often uses the same pattern of shifter movement with a single or multiple switches to engage the next sequence of gears.

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Symptoms of a Bad Transmission:

• Odd sounds (whirring, squealing, bumping, or thumping)

• Grinding noise.

• Transmission jumps out of gear (into neutral)

• Difficulty shifting gears.

• Car stuck in one gear.

• Car that can't get into gear.

• Leaking transmission oil.

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Here are some of the most common forms of gearbox failure. The major cause is inadequate lubrication caused by under filling, incorrect specification, mixing or incompatibility, incorrect lubrication and intervals, deteriorated grease or oil, water contamination and particulate contamination