手动变速器外文文献翻译、中英文翻译

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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 more of a thrill to drive than a tautly suspended sport

sedan, snort coupe or two-sealer 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 transaxle. This is because the

transmission, differential and drive axles are one complete 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 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 cluster-gear assembly rotates any time the clutch is engaged to

a running engine，whether or not the transmission is in gear or in neutral.

There are two basic types of manual transmissions. The sliding-gear type and the

constant-mesh design. With the basic――and now obsolete――sliding-gear

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 driver has to unmesh one gear before

being able to mesh another. With these older transmissions, gear clash is a problem

because the gears are all rotating at different speeds.

All modern transmissions are of the constant-mesh type, which still uses a

similar gear arrangement as the sliding-gear type. However ，all the mainshaft gears

are in constant mesh with the cluster gears. This is possible because the gears on the

mainshaft are not 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.

Alongside each gear on the mainshaft is a dog clutch, with a hub that’s positively

splined to the shaft and an outer ring that can slide over against each gear. Both the

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 "synchronized" manual transmission is equipped with synchronizers. A

synchronizer 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 between a pair of main drive gears. Held in place by the lock rings ，the

shifter plates position the sleeve over the hub while also holding the floating blocking

rings in proper alignment.

A synchro’s inner hub and sleeve are made of steel, but the blocking ring――the

part of the synchro that rubs on the gear to change its speed――is usually made of a

softer material, such as brass. The blocking ring has teeth that match the teeth on the

dog clutch. Most synchros perform double duty――they push the synchro in one

direction and lock one gear to the mainshaft. Push the synchro the other way and it

disengages from the first gear, passes through a neutral position, and engages a gear

on the other side.

That’s the basics on the inner workings of a manual transmission. As for

advances, they have been extensive over the years, mainly in the area of additional

gears. Back in the 60’s, four-speeds were common in American and European

performance cars ．Most of these transmissions had 1:1 final-drive ratios with no

overdrives. Today, overdriven five-speeds are standard on practically all passenger

cars available with a manual gearbox.

Overdrive is an arrangement of gearing that provides more revolutions of the

driven shaft（the driveshaft going to the wheels）than the driving shaft（crankshaft

of the engine ）. For example, a transmission with a fourth-gear ratio of 1:1 and a

fifth-gear ratio of 0.70:1 will reduce engine rpm by 30 percent, while the vehicle

maintains the same road speed. Thus, fuel efficiency will improve and engine wear

will be notably reduced. Today, six-speed transmissions are becoming more and more

common. One of the first cars sold in America with a six-speed was the ’89 Corvette.

Germany, this tough-as-nails six-speed was available in the Corvette up to the

conclusion of the ’96 model year. Today，the Corvette uses a Tremec T56 six-speed

mounted at the back of the car.

Many cars are available today with six-speeds, including the Mazda Miata,

Porsche Boxster S and 911, Dodge Viper, Mercedes-Benz SLK320, Honda S2000,

Toyota Celica GT-S and many others. Some of these gearboxes provide radical 50-

percent (0.50:1) sixth-gear overdrives such as in the Viper and Corvette, while others

provide tightly spaced gear ratios like in the S2000 and Celica for spirited backroad

performance driving. While the bigger cars mentioned above such as the Viper and

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摘要：

附　　录附录A.ManualTransmissionIt’snosecretthatcarswithmanualtransmissionsareusuallymorefuntodrivethantheautomatic-equippedcounterparts.Ifyouhaveevenapassinginterestintheactofdriving,thenchancesareyoualsoappreciateafine-shiftingmanualgearbox.Buthowdoesamanualtransmissionactuallywork?Ahistoryhowsthatmanua...

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