手动变速器外文翻译
附 录
附录A.
Manual Transmission
It’s no secret that cars with manual transmissions are usually more fun to drive than the
automatic-equipped counterparts. If you have even a passing interest in the act of driving,
then chances are you also appreciate a fine-shifting manual gearbox. But how does a manual
transmission actually work?
A history hows that manual transmissions preceded automatics by several decades. In
fact,up until General Motors offered an automatic in 1938, all cars were of the shift-it-
yourself variety. While it’s logical for many types of today’s vehicles to be equipped with an
automatic――such as a full-size sedan, SUV or pickup――the fact remains that nothing is
m o r e o f a t h r i l l t o d r i v e t h a n a t a u t l y s u s p e n d e d s p o r t s e d a n , s n o r t c o u p e o r t w o - s e a l e r
equipped with a precise-shifting five-or six-speed gearbox.
We know whicn types or cars have manual trannies. Now let’s take a look at how they
work. From the most basic four-speed manual in a car from the’60s to the most high-tech
six-speed one in a car of today, the principles of a manual gearbox are the same. The driver
must shift from gear to gear. Normally, a manual transmission bolts to a clutch housing (or
bell housing), in turn, bolts to the back of the engine. If the vehicle has front-wheel drive,
the transmission still attaches to the engine in a similar fashion but is usually referred to as a
t r a n s a xl e . T h i s i s b ec a u s e t h e t r a n s m i ss i o n , d i ff e r e n t i a l a n d dr iv e a x l e s a r e o ne c o m p l e t e
unit. In a front-wheel-drive car, the transmission also serves as part of the front axle for the
front wheels. In the remaining text, a transmission and a transaxle will both be referred to
using the term transmission.
The function of any transmission is transferring engine power to the driveshaft and rear
wheels (or axle halfshafts and front wheels in a front-wheel-drive vehicle). Gears inside the
transmission change the vehicle’s drive-wheel speed and torque in relation to engine speed
and torque.Lower(numerically higher) gear ratios serve as torque multipliers and help the
engine to develop enough power to accelerate from a standstill.
Initially, power and torque from the engine comes into the front of the transmissions
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and rotates the main drive gear (or input shaft), which meshes with the cluster or counter
shaft gear――a series of gears forged into one piece that resembles a cluster of gears. The
c l u s t e r - g e a r a s s e m b l y r o t a t e s a n y t i m e t h e c l u t c h i s e n g a g e d t o a r u n n i n g
engine,whether or not the transmission is in gear or in neutral.
T h e r e a r e t w o b a s i c t y p e s o f m a n u a l t r a n s m i s s i o n s . T h e s l i d i n g - g e a r t y p e a n d t h e
c o n s t a n t - m e s h d e s i g n . W i t h t h e b a s i c ― ― a n d n o w o b s o l e t e ― ― s l i d i n g - g e a r
type,nothing is turning inside the transmission case except the main drive gear and cluster
gear when the trans is in neutral. In order to mesh the gears and apply engine power to move
the vehicle, the driver presses the clutch pedal and moves the shifter handle, which in turn
moves the shift linkage and forks to slide a gear along the mainshaft, which is mounted
directly above the cluster. Once the gears are meshed, the clutch pedal is released and the
engine’s power is sent to the drive wheels. There can be several gears on the mainshaft of
different diameters and tooth counts, and the transmission shift linkage is designed so the
d r i v e r h a s t o u n m e s h o n e g e a r b e f o r e b e i n g a b l e t o m e s h a n o t h e r . W i t h t h e s e o l d e r
transmissions, gear clash is a problem because the gears are all rotating at different speeds.
Al l m od e rn tr a n sm i ss i on s a r e of the co n st ant - me s h t yp e , w hi c h s ti l l u s es a si m i la r
gear arrangement as the sliding-gear type. However,all the mainshaft gears are in constant
m e s h w i t h t h e c l u s t e r g e a r s . T h i s i s p o s s i b l e b e c a u s e t h e g e a r s o n t h e m a i n s h a f t a r e n o t
splined to the shaft, but are free to rotate on it. With a constant-mesh gearbox, the main drive
gear, cluster gear and all the mainshaft gears are always turning, even when the transmission
is in neutral.
A l o n g s i d e e a c h g e a r o n t h e m a i n s h a f t i s a d o g c l u t c h , w i t h a h u b t h a t ’ s p o s i t i v e l y
s p l i n e d t o t h e s h a f t a n d a n o u t e r r i n g t h a t c a n s l i d e o v e r a g a i n s t e a c h g e a r . B o t h t h e
mainshaft gear and the ring of the dog clutch have a row of teeth. Moving shift linkage
moves the dog clutch against the adjacent mainshaft gear, causing the teeth to interlock and
solidly lock the gear to the mainshaft.
To prevent gears from grinding or clashing during engagement, a constant-mesh, fully
" s y n c h r o n i z e d " m a n u a l t r a n s m i s s i o n i s e q u i p p e d w i t h s y n c h r o n i z e r s . A s y n c h r o n i z e r
typically consists of an inner-splined hub, an outer sleeve, shifter
plates,lock rings(or springs)and blocking rings. The hub is splined onto the mainshaft
b e t w e e n a p a i r o f m a i n d r i v e g e a r s . H e l d i n p l a c e b y t h e l o c k
r i n g s,t he sh ift e r p la t es po s it i on the sl ee v e o v er th e h ub wh i le als o h old i ng th e f l oat ing
2
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附 录附录A.ManualTransmissionIt’snosecretthatcarswithmanualtransmissionsareusuallymorefuntodrivethantheautomatic-equippedcounterparts.Ifyouhaveevenapassinginterestintheactofdriving,thenchancesareyoualsoappreciateafine-shiftingmanualgearbox.Buthowdoesamanualtransmissionactuallywork?Ahistoryhowsthatmanua...
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作者:闻远设计
分类:课程设计课件资料
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时间:2022-10-23

