UNIT 8
CLUTCHES,
MANUAL TRANSMISSIONS
AND DRIVE LINE
TEXT A
Clutches and Manual Transmissions
PROFESSIONAL ENGLISH
UNIT 7
CLUTCHES,MANUAL TRANSMISSIONS
AND DRIVE LINE
TEXT A
Clutches and Manual Transmissions
Clutches
Manual Transmission (M/T)
本次课学习内容本次课学习目标
掌握离合器和手动变速器的有关英文专业词汇
能够较好地用已知翻译技巧进行课文翻译
具有较高的阅读速度
NEW WORDS
transaxle [?tr? ns'? k
sl]
n.变速驱动桥
neutral ['nju:tr?l] a.中立的,中性的； n.空档
throw-out ['θrou'aut] n.抛开，断开，次品，分离
bronze [br?nz] n.青铜,铜像； a.青铜色的
bushing ['bu∫i?] n.轴衬,衬套，套管
asbestos [? z'best?s] n.石棉
woven ['wouv?n] a.编成的，纺织的
mold [mould] n.模子,铸型； v.铸 [塑 ]造，模制
rivet ['rivit] n.铆钉； v,铆接，固定
cup [k?p] n.杯； v.使成杯状
segment ['segm?nt] n.段,节,片，扇形
cushion ['ku∫?n] n.垫子,软垫,衬垫，缓冲垫 [器 ]
revolve [ri'v?lv] v.(使 )旋转,循环出现
pinch [pint∫] v.夹紧，挤压，节省
seize [si:z] v.挤住，卡住，抓住,逮住,夺取
overdrive ['ouv?'drai
v]
n.超速传动（常常简写为 O/D）
mileage ['mailid] n.英里数，里程
drop-forge ['dr?p'f?:d] v.锤锻,落锤锻造
spur [sp?:] n.正齿
washer ['w?∫?] n.垫圈,洗衣机,洗碗机，洗涤器
clash [kl? ∫] v.(使 )发出撞击声,猛撞,冲突
smash [sm? ∫] v.碰撞，猛撞
literally ['lit?r?li] ad.照字面意义,逐字地，确确实实地
PHRASES AND EXPRESSIONS
drive line 传动系统
clutch disc 离合器从动盘
pressure plate 离合器压盘
throw-out
bearing
分离轴承
release bearing 分离轴承
pilot bearing 导向轴承
ball bearing 球轴承
dual mass
flywheel
双质量飞轮
be constructed of 用 … 制造
splined hub 花键毂
release lever 分离杆
gear ratio 传动比
reduction gear 减速档
direct drive gear 直接档
overdrive gear 超速档
differential gear 差速器
reverse gear 倒档
fuel mileage 燃油经济性
shifting
mechanism
换档机构
extension
housing
加长壳，后壳
precision
machinery
精密机械
end play 轴向间隙
cluster gear 齿轮组，塔齿轮
thrust washer 止推垫片
synchronizing
mechanism 同步机构
synchronized gear 同步器，同步机构
Clutches and Manual Transmissions
Clutches
The function of the clutch assembly in cars and trucks with
manual transmissions or transaxles is to connect or disconnect
the flow of power from the engine to the drive line,Although
there are many variations in the design of clutches,all work on
the same basic principle,
Clutch Purpose
A clutch is a mechanism designed to connect or disconnect
power from one working part to another,In a vehicle,the
clutch is used to transmit engine power and to disengage the
engine and transmission when shifting gears,It also allows the
engine to operate when the vehicle is stopped without placing
the transmission in neutral (out of gear).
Clutch Construction
The modern clutch is a single plate,dry disc (see Figure 8-
1),It consists of five major parts,flywheel,clutch disc,
pressure plate assembly,throw-out bearing,and clutch
linkage,Other parts which make up the clutch assembly are
the transmission input shaft and clutch housing,
Figure 8-1 A typical clutch
Flywheel
In addition to providing a base for the starter ring gear,the
flywheel forms the foundation on which the other clutch parts
are attached,The flywheel used with manual transmissions is
thick to enable it to absorb a large amount of heat generated
by clutch operation.
The clutch side is machined smooth to provide a friction
surface,Holes are drilled into the flywheel to provide a means
of mounting the clutch assembly,A hole is usually drilled
directly into the rear of the crankshaft,This hole allows a
bearing to be installed in the center of the flywheel.
The bearing in the center of the flywheel will act as a
support for the outboard end of the transmission input shaft,It
is referred to as a pilot bearing,The pilot bearing may be either
a ball bearing or a bronze bushing,
Dual Mass Flywheel
A dual mass flywheel is sometimes used with diesel engines,
To help absorb engine power stroke pulsations,springs
mounted inside the flywheel act as a shock absorbing unit when
the flywheel sections partially compress,smoothing out the
power flow,They also help to reduce stress on the clutch and
transmission parts.
Clutch Disc
The clutch disc is round and constructed of thin,high quality
steel with a splined (grooved) hub placed in the center,The
hub splines engage splines on the transmission input shaft,The
clutch disc can move back and forth on the shaft,but when the
disc is turned,the shaft must turn also.
Both sides of its outer edge are covered with friction material,
It is often made of asbestos or other high temperature material
and copper wires either woven or molded together,It is riveted
to the disc.
To assist in smooth engagement,the disc outer edges are
often split and each piece cupped,The friction material is
riveted to these segments,When the disc is compressed,these
cupped segments act as a spring-like cushion.
Pressure Plate
The clutch pressure plate disc is the same in each type of
pressure plate assembly,It is made of a thick piece of cast iron
for maximum heat absorption,It is round and about the same
diameter as the clutch disc,One side of the pressure plate is
machined smooth,This side will press the clutch disc facing area
against the flywheel,The outer side has various shapes to
facilitate attachment of springs and release mechanisms.
Release Lever Operating Mechanism
This mechanism consists of a ball bearing normally referred
to as a throw-out bearing or release bearing,This bearing is
mounted on a sleeve or collar that slides back and forth on a
hub that is an integral part of the transmission front bearing
retainer.
The throw-out bearing is filled with grease at the factory and does
not need service during its useful life,Another type of throw-out
bearing is the graphite type,This bearing employs a ring of
graphite to press against a smooth plate fastened to the clutch
levers,The throw-out bearing sleeve is moved in and out by a
throw-out fork or clutch fork,This fork is usually pivoted on a ball
head stud,A return spring pulls the fork away from the pressure
plate.
Clutch Operation
The flywheel,clutch cover,release levers,and pressure plate all
revolve as a single unit,The transmission input shaft and the
clutch disc are splined together,forming another unit.
The only time the clutch disc will turn (vehicle standing still) is
when it is pinched between the flywheel and pressure plate,When
the release levers draw the pressure plate away from the flywheel,
the clutch disc will stand still while every thing else continues to
revolve,When the pressure plate travels back toward the flywheel,
the disc is seized and forced to turn the transmission input shaft,
Figure 8-2,
a) disengaged b) engaged
Figure 8-2 Clutch operation simplified
Manual Transmission (M/T)
Transmission Gear Ratios
The modern manual transmission can provide the driver
with up to six forward gear ratios,The reduction gears provide
gear ratios of approximately 3.5:1 (stated as 3.5 to 1) for the
lowest gear,to about 1.5:1 for the highest,The direct drive
gear has a 1:1 gear ratio,The overdrive gears have a gear
ratio of about 0.7:1.
By selecting one of the ratios,it is possible to operate the
vehicle under all normal conditions,In addition,torque is
multiplied more through the differential gears,Ratios vary
from vehicle to vehicle,depending on engine horsepower and
vehicle weight,A reverse gear is also used,The reverse ratio is
usually about 3:1,The five-speed transmission has an
overdrive ratio,The overdrive ratio is incorporated into newer
transmissions to increase fuel mileage and lower emissions.
Figure 8-3 The relative positions of the four shafts
in the transmission case
Transmission Construction
A typical transmission consists of a case,four shafts,
bearings,gears,synchronizers,and a shifting mechanism,
Figure 8-3 shows the relative positions of the four shafts and
their gears in the case,
Transmission Case
The transmission case holds the transmission gears,shafts,
bearings,and washers,It bolts to the rear of the engine,or to
the clutch housing,Many transmission cases and clutch
housings are one-piece units,Most transmission cases are
made of cast iron or aluminum and have a separate extension
housing,which supports the output shaft,This housing may
also contain the speedometer gear,The rear engine mount is
usually attached to the extension housing.
Transmission Gear
Transmission gears are made of high quality steel,carefully
heat-treated to produce smooth,hard surface gear teeth with a
softer,but very tough interior [1],They are drop-forged
(machine hammered into shape) while red hot,The teeth and
other critical areas are cut on precision machinery.
The teeth on transmission gears are cut into spur and helical
patterns,The helical gear is superior in that it runs more quietly
and is stronger because more tooth area is in contact [2],
Helical gears must be mounted firmly,since there is a tendency
for them to slide apart due to the spiral shape,Gear end play in
the cluster gear and some other gears and shafts is controlled
by the use of bronze and steel thrust washers,These washers
are installed on the end of the gear shafts between the moving
gears and the stationary transmission case.
There must be some clearance between the gear teeth to allow
for lubrication,expansion and possible size irregularity,This
clearance is very small (a few thousandths of an inch).
Synchronizing Mechanism
Once the vehicle is in motion,the drive line will turn the
output shaft continuously,As a result,the sliding gears will
also be turning,When an attempt is made to mesh them with
any of the cluster gears (which tend to stop when the clutch is
depressed),the gear teeth will be subjected to damaging
impact forces,The sound of gear clash when shifting results
from the sliding gear teeth literally smashing against the
cluster gear.
It is obvious that for one gear to mesh with another quietly
and without damage,both gears must be rotating at nearly
the same speed,Modern manual transmissions and transaxles
have synchronized gears (shown in Figure8-4),with special
internal clutches to prevent gear clash when shifting,The
purpose of the synchronizer is to move ahead of the unit that
is to be meshed,seize the other unit,and bring the rotational
speed of both units together [3],Once both units are rotating
at the same speed,they may be meshed.
Figure 8-4 Synchronized gear
小结
Clutches
Clutch Purpose
Clutch Operation
Clutch Construction
Manual Transmission (M/T)
Transmission Gear Ratios
Transmission Construction
作业
熟记相关专业词汇
P191 EXERCIES Ⅰ &Ⅱ
CLUTCHES,
MANUAL TRANSMISSIONS
AND DRIVE LINE
TEXT A
Clutches and Manual Transmissions
PROFESSIONAL ENGLISH
UNIT 7
CLUTCHES,MANUAL TRANSMISSIONS
AND DRIVE LINE
TEXT A
Clutches and Manual Transmissions
Clutches
Manual Transmission (M/T)
本次课学习内容本次课学习目标
掌握离合器和手动变速器的有关英文专业词汇
能够较好地用已知翻译技巧进行课文翻译
具有较高的阅读速度
NEW WORDS
transaxle [?tr? ns'? k
sl]
n.变速驱动桥
neutral ['nju:tr?l] a.中立的,中性的； n.空档
throw-out ['θrou'aut] n.抛开，断开，次品，分离
bronze [br?nz] n.青铜,铜像； a.青铜色的
bushing ['bu∫i?] n.轴衬,衬套，套管
asbestos [? z'best?s] n.石棉
woven ['wouv?n] a.编成的，纺织的
mold [mould] n.模子,铸型； v.铸 [塑 ]造，模制
rivet ['rivit] n.铆钉； v,铆接，固定
cup [k?p] n.杯； v.使成杯状
segment ['segm?nt] n.段,节,片，扇形
cushion ['ku∫?n] n.垫子,软垫,衬垫，缓冲垫 [器 ]
revolve [ri'v?lv] v.(使 )旋转,循环出现
pinch [pint∫] v.夹紧，挤压，节省
seize [si:z] v.挤住，卡住，抓住,逮住,夺取
overdrive ['ouv?'drai
v]
n.超速传动（常常简写为 O/D）
mileage ['mailid] n.英里数，里程
drop-forge ['dr?p'f?:d] v.锤锻,落锤锻造
spur [sp?:] n.正齿
washer ['w?∫?] n.垫圈,洗衣机,洗碗机，洗涤器
clash [kl? ∫] v.(使 )发出撞击声,猛撞,冲突
smash [sm? ∫] v.碰撞，猛撞
literally ['lit?r?li] ad.照字面意义,逐字地，确确实实地
PHRASES AND EXPRESSIONS
drive line 传动系统
clutch disc 离合器从动盘
pressure plate 离合器压盘
throw-out
bearing
分离轴承
release bearing 分离轴承
pilot bearing 导向轴承
ball bearing 球轴承
dual mass
flywheel
双质量飞轮
be constructed of 用 … 制造
splined hub 花键毂
release lever 分离杆
gear ratio 传动比
reduction gear 减速档
direct drive gear 直接档
overdrive gear 超速档
differential gear 差速器
reverse gear 倒档
fuel mileage 燃油经济性
shifting
mechanism
换档机构
extension
housing
加长壳，后壳
precision
machinery
精密机械
end play 轴向间隙
cluster gear 齿轮组，塔齿轮
thrust washer 止推垫片
synchronizing
mechanism 同步机构
synchronized gear 同步器，同步机构
Clutches and Manual Transmissions
Clutches
The function of the clutch assembly in cars and trucks with
manual transmissions or transaxles is to connect or disconnect
the flow of power from the engine to the drive line,Although
there are many variations in the design of clutches,all work on
the same basic principle,
Clutch Purpose
A clutch is a mechanism designed to connect or disconnect
power from one working part to another,In a vehicle,the
clutch is used to transmit engine power and to disengage the
engine and transmission when shifting gears,It also allows the
engine to operate when the vehicle is stopped without placing
the transmission in neutral (out of gear).
Clutch Construction
The modern clutch is a single plate,dry disc (see Figure 8-
1),It consists of five major parts,flywheel,clutch disc,
pressure plate assembly,throw-out bearing,and clutch
linkage,Other parts which make up the clutch assembly are
the transmission input shaft and clutch housing,
Figure 8-1 A typical clutch
Flywheel
In addition to providing a base for the starter ring gear,the
flywheel forms the foundation on which the other clutch parts
are attached,The flywheel used with manual transmissions is
thick to enable it to absorb a large amount of heat generated
by clutch operation.
The clutch side is machined smooth to provide a friction
surface,Holes are drilled into the flywheel to provide a means
of mounting the clutch assembly,A hole is usually drilled
directly into the rear of the crankshaft,This hole allows a
bearing to be installed in the center of the flywheel.
The bearing in the center of the flywheel will act as a
support for the outboard end of the transmission input shaft,It
is referred to as a pilot bearing,The pilot bearing may be either
a ball bearing or a bronze bushing,
Dual Mass Flywheel
A dual mass flywheel is sometimes used with diesel engines,
To help absorb engine power stroke pulsations,springs
mounted inside the flywheel act as a shock absorbing unit when
the flywheel sections partially compress,smoothing out the
power flow,They also help to reduce stress on the clutch and
transmission parts.
Clutch Disc
The clutch disc is round and constructed of thin,high quality
steel with a splined (grooved) hub placed in the center,The
hub splines engage splines on the transmission input shaft,The
clutch disc can move back and forth on the shaft,but when the
disc is turned,the shaft must turn also.
Both sides of its outer edge are covered with friction material,
It is often made of asbestos or other high temperature material
and copper wires either woven or molded together,It is riveted
to the disc.
To assist in smooth engagement,the disc outer edges are
often split and each piece cupped,The friction material is
riveted to these segments,When the disc is compressed,these
cupped segments act as a spring-like cushion.
Pressure Plate
The clutch pressure plate disc is the same in each type of
pressure plate assembly,It is made of a thick piece of cast iron
for maximum heat absorption,It is round and about the same
diameter as the clutch disc,One side of the pressure plate is
machined smooth,This side will press the clutch disc facing area
against the flywheel,The outer side has various shapes to
facilitate attachment of springs and release mechanisms.
Release Lever Operating Mechanism
This mechanism consists of a ball bearing normally referred
to as a throw-out bearing or release bearing,This bearing is
mounted on a sleeve or collar that slides back and forth on a
hub that is an integral part of the transmission front bearing
retainer.
The throw-out bearing is filled with grease at the factory and does
not need service during its useful life,Another type of throw-out
bearing is the graphite type,This bearing employs a ring of
graphite to press against a smooth plate fastened to the clutch
levers,The throw-out bearing sleeve is moved in and out by a
throw-out fork or clutch fork,This fork is usually pivoted on a ball
head stud,A return spring pulls the fork away from the pressure
plate.
Clutch Operation
The flywheel,clutch cover,release levers,and pressure plate all
revolve as a single unit,The transmission input shaft and the
clutch disc are splined together,forming another unit.
The only time the clutch disc will turn (vehicle standing still) is
when it is pinched between the flywheel and pressure plate,When
the release levers draw the pressure plate away from the flywheel,
the clutch disc will stand still while every thing else continues to
revolve,When the pressure plate travels back toward the flywheel,
the disc is seized and forced to turn the transmission input shaft,
Figure 8-2,
a) disengaged b) engaged
Figure 8-2 Clutch operation simplified
Manual Transmission (M/T)
Transmission Gear Ratios
The modern manual transmission can provide the driver
with up to six forward gear ratios,The reduction gears provide
gear ratios of approximately 3.5:1 (stated as 3.5 to 1) for the
lowest gear,to about 1.5:1 for the highest,The direct drive
gear has a 1:1 gear ratio,The overdrive gears have a gear
ratio of about 0.7:1.
By selecting one of the ratios,it is possible to operate the
vehicle under all normal conditions,In addition,torque is
multiplied more through the differential gears,Ratios vary
from vehicle to vehicle,depending on engine horsepower and
vehicle weight,A reverse gear is also used,The reverse ratio is
usually about 3:1,The five-speed transmission has an
overdrive ratio,The overdrive ratio is incorporated into newer
transmissions to increase fuel mileage and lower emissions.
Figure 8-3 The relative positions of the four shafts
in the transmission case
Transmission Construction
A typical transmission consists of a case,four shafts,
bearings,gears,synchronizers,and a shifting mechanism,
Figure 8-3 shows the relative positions of the four shafts and
their gears in the case,
Transmission Case
The transmission case holds the transmission gears,shafts,
bearings,and washers,It bolts to the rear of the engine,or to
the clutch housing,Many transmission cases and clutch
housings are one-piece units,Most transmission cases are
made of cast iron or aluminum and have a separate extension
housing,which supports the output shaft,This housing may
also contain the speedometer gear,The rear engine mount is
usually attached to the extension housing.
Transmission Gear
Transmission gears are made of high quality steel,carefully
heat-treated to produce smooth,hard surface gear teeth with a
softer,but very tough interior [1],They are drop-forged
(machine hammered into shape) while red hot,The teeth and
other critical areas are cut on precision machinery.
The teeth on transmission gears are cut into spur and helical
patterns,The helical gear is superior in that it runs more quietly
and is stronger because more tooth area is in contact [2],
Helical gears must be mounted firmly,since there is a tendency
for them to slide apart due to the spiral shape,Gear end play in
the cluster gear and some other gears and shafts is controlled
by the use of bronze and steel thrust washers,These washers
are installed on the end of the gear shafts between the moving
gears and the stationary transmission case.
There must be some clearance between the gear teeth to allow
for lubrication,expansion and possible size irregularity,This
clearance is very small (a few thousandths of an inch).
Synchronizing Mechanism
Once the vehicle is in motion,the drive line will turn the
output shaft continuously,As a result,the sliding gears will
also be turning,When an attempt is made to mesh them with
any of the cluster gears (which tend to stop when the clutch is
depressed),the gear teeth will be subjected to damaging
impact forces,The sound of gear clash when shifting results
from the sliding gear teeth literally smashing against the
cluster gear.
It is obvious that for one gear to mesh with another quietly
and without damage,both gears must be rotating at nearly
the same speed,Modern manual transmissions and transaxles
have synchronized gears (shown in Figure8-4),with special
internal clutches to prevent gear clash when shifting,The
purpose of the synchronizer is to move ahead of the unit that
is to be meshed,seize the other unit,and bring the rotational
speed of both units together [3],Once both units are rotating
at the same speed,they may be meshed.
Figure 8-4 Synchronized gear
小结
Clutches
Clutch Purpose
Clutch Operation
Clutch Construction
Manual Transmission (M/T)
Transmission Gear Ratios
Transmission Construction
作业
熟记相关专业词汇
P191 EXERCIES Ⅰ &Ⅱ
