MANUAL GEARBOXES
9.1 MANUAL GEARBOX CLASSIFICATION
Gearboxes are normally classi?ed according to the number of toothed wheel
couples (stages) involved in the transmission of motion at a given speed; in the
case of manual vehicle transmissions, the number to be taken into account is
that of the forward speeds only, without consideration of the ?nal gear, even if included in the gearbox.
Therefore there are:
?Single stage gearboxes
?Dual stage or countershaft gearboxes
?Multi stage gearboxes
Figure 9.1 sho ws the three con?gurations for a four speed gearbox.
It is useful to comment on the generally adopted rules of these schemes.
Each wheel is represented by a segment whose length is proportional to the pitch diameter of the gear; the segment is ended by horizontal strokes, representing
the tooth width. If the segment is interrupted where crossing the shaft, the
gear wheel is idle; the opposite occurs if the segment crosses the line of the
shaft without interruption. Then the wheel rotates with the shaft. Hubs are represented according to the same rules, while sleeves are represented with a
pair of horizontal strokes. Arrows show the input and output shafts.
Single stage gearboxes are primarily applied to front wheel driven vehicles,
because in these it is useful that the input and the output shaft are o?set; in
G. Genta and L. Morello, The Automotive Chassis, Volume 1: Components Design, 425 Mechanical Engineering Series,
c Springer Science+Business Media B.V. 2009426 9. MANUAL GEARBOXES FIGURE 9.1. Schemes for a four spee
d gearbox shown in thre
e di?erent con?gurations: a: single stage, b: double stage and c: triple stage.
conventional vehicles, on the other hand, it is better that input and output shafts
are aligned.
This is why rear wheel driven vehicles usually adopt a double stage gearbox.
The multi-stage con?guration is sometime adopted on front wheel driven
vehicles with transversal engine, because the transversal length of the gearbox
can be shortened; it is used when the number of speeds or the width of the gears
do not allow a single stage transmission to be used.
It should be noted that on a front wheel driven vehicle with transversal
engine, having decided on the value of the front track and the size of the tire,
the length of the gearbox has a direct impact on the maximum steering angle of
the wheel and therefore on the minimum turning radius.
The positive result on the transversal dimension of multi-stage gearboxes is
o?set by higher mechanical losses, due to the increased number of engaged gear wheels.
It should be noted that in triple stage gearboxes, shown in the picture, the
axes of the three shafts do not lie in the same plane, as the scheme seems to
show. In a lateral view, the outline of the three shafts should be represented as
the vertices of a triangle; this lay-out reduces the transversal dimension of the gearbox. In this case and others, as we will show later, the drawing is represented
by turning the plane of the input shaft and of the counter shaft on the plane of
the counter shaft and of the output shaft.
Gear trains used in reverse speed are classi?ed separately. The inversion of
speed is achieved by using an additional gear. As a matter of fact, in a train of
three gears, the output speed has the same direction as the input speed, while
the other trains of two gears only have an output speed in the opposite direction;
the added gear is usually called idler.
The main con?gurations are reported in Fig. 9.2.
In scheme a, an added countershaft shows a sliding idler, which can match
two close gears that are not in contact, as, for example, the input gear of the
?rst speed and the output gear of the second speed. It should be noted that, in
this scheme, the drawing does not preserve the actual dimension of the parts.9.1 Manual gearbox classi?cation 427
FIGURE 9.2. Schemes used for reverse speed; such schemes ?t every type of gearbox
lay-out.
Scheme b shows instead two sliding idlers, rotating together; this arrange-
ment o?ers additional freedom in obtaining a given transmission ratio. The coun-
tershaft is o?set from the drawing plane; arrows show the gear wheels that match
when the reverse speed is engaged.
Scheme c is similar to a in relation to the idler; it pairs an added speci?c
wheel on the output shaft with a gear wheel cut on the shifting sleeve of the ?rs t
and second speed, when it is in idle position.
Con?guration d shows a dedicated pair of gears, with a ?xed idler and a
shifting sleeve.
The following are the advantages and disadvantages of the con?gurations
shown in the ?gure.
?Schemes a, b and c are simpler, but preclude the application of synchro-
nizers (because couples are not always engaged), nor do they allow the use
of helical gears (because wheels must be shifted by sliding).
?Scheme d is more complex but can include a synchronizer and can adopt
helical gears.
?Schemes a, b and c do not increase gearbox length.428 9. MANUAL GEARBOXES
9.2 MECHANICAL EFFICIENCY
The mechanical e?ciency of an automotive gear wheel transmission is high com-
pared to other mechanisms performing the same function; indeed, the value of
this e?ciency should not be neglected when calculating dynamic performance
and fuel consumption. The continuous e?ort of to limit fuel consumption justi-
?es the care of transmission designers in reducing mechanical losses.
Total transmission losses are conveyed up by terms that are both dependent
and independent of the processed power; the primary terms are:
?Gearing losses; these are generated by friction between engaging teeth
(power dependent) and by the friction of wheels rotating in air and oil
(power independent).
?Bearing losses; these are generated by the extension of the contact area of
rolling bodies and by their deformation (partly dependent on and partly
independent of power) and by their rotation in the air and oil (power
independent).
?Sealing losses; they are generated by friction between seals and rotating
shafts and are power independent.
?Lubrication losses; these are generated by the lubrication pump, if present,
and are power independent.
All these losses depend on the rotational speed of parts in contact and,
therefore, on engine speed and selected transmission ratio.
Table 9.1 reports the values of mechanical e?ciency to be adopted in calcu-
lations considering wide open throttle conditions; these values consider a pair of
gearing wheels or a complete transmission with splash lubrication; in the same
table we can see also the e?ciency of a complete powershift epicycloidal auto-
matic transmission and a steel belt continuously variable transmission. For the
two last transmissions, the torque converter must be considered as locked-up.
TABLE 9.1. Mechanical e?ciency of di?erent transmission mechanisms.
Mechanism type E?ciency (%)
Complete manual gearbox
with splash lubrication 92–97
Complete automatic transmission
(ep. gears) 90–95
Complete automatic gearbox
(steel belt; without press. contr.) 70–80
Complete automatic gearbox
(steel belt; with press. contr.) 80–86
Pair of cyl. gears 99.0–99.5
Pair of bevel gears 90–939.2 Mechanical e?ciency 429
FIGURE 9.3. Contributions to total friction loss of a single stage gearbox designed for
300 Nm as function of input speed.
It is more correct to reference power loss measurement as a function of
rotational input speed rather than e?ciency. Figure 9.3 shows the example of
a double stage transmission, in fourth speed, at maximum power; the di?erent
contributions to the total are shown.
This kind of measurement is made by disassembling the gearbox step by
step, thus eliminating the related loss.
In the ?rst step all synchronizer rings are removed, leaving the synchronizer
hubs only; mechanical losses of non-engaged synchronizers are, therefore, mea-
surable. The loss is due to the relative speed of non-engaged lubricated conical
surfaces; the value of this loss depends, obviously, on speed and the selected
transmission ratio.
In the second step all rotating seals are removed.
In the third step the lubrication oil is removed, and therefore, the bulk of
the lubrication losses is eliminated; some oil must remain in order to leave the
contact between teeth una?ected.
By removing those gear wheels not involved in power transmission, their
mechanical losses are now measurable.
The rest of the loss is due to bearings; the previous removal of parts can
a?ect this value.
A more exhaustive approach consists in measuring the complete e?ciency
map; the e?ciency can be represented as the third coordinate of a surface, where
the other two coordinates are input speed and engine torque. E?ciency calcu-
lations can be made by comparing input and output torque of a working trans-
mission.
Such map can show how e?ciency reaches an almost constant value at a
modest value of the input torque; it must not be forgotten that standard fuel
consumption evaluation cycles involve quite modest values of torque and there-
fore imply values of transmission e?ciency that are changing with torque.
Figure 9.4 shows a qualitative cross section of the aforesaid map, cut at
constant engine speed. It should be noted that e?ciency is also zero at input430 9. MANUAL GEARBOXES
FIGURE 9.4. Mechanical e?ciency map, as a function of input torque at constant
engine speed; the dotted line represents a reasonable approximation of this curve, to be
used on mathematical models for the prediction of performance and fuel consumption.
torque values slightly greater than zero; as a matter of fact, friction implies a
certain minimum value of input torque, below which motion is impossible.
A good approximation to represent mechanical e?ciency can be made using
the dotted broken line as an interpolation of the real curve.
9.3 MANUAL AUTOMOBILE GEARBOXES
9.3.1 Adopted schemes
In manual gearboxes, changing speed and engaging and disengaging the clutch
are performed by driver force only.
This kind of gearbox is made with helical gears and each speed has a syn-
chronizer; some gearboxes do not use show the synchronizer for reverse speed,
particularly those in economy minicars.
We previously discussed a ?rst classi?cation; additional information is the
speed number, usually between four and six.
Single stage gearboxes are used in trans-axles; they are applied, with some
exceptions, to front wheel driven cars with front engine and rear driven cars with
rear engine; this is true with longitudinal and transversal engines.
In all these situations the ?nal drive is included in the gearbox, which is
therefore also called transmission.
Countershaft double stage gearboxes are used in conventionally driven cars,
where the engine is mounted longitudinally in the front and the driving axle is
the rear axle. If the gearbox is mounted on the rear axle, in order to improve the
weight distribution, the ?nal drive could be included in the gearbox.9.3 Manual automobile gearboxes 431
By multi-stage transmissions, some gear wheels could be used for di?erent
speeds. The number of gearing wheels could increase at some speeds; this nor-
mally occurs at low speeds, because the less frequent use of these speeds reduces
the penalty of lower mechanical e?ciency on fuel consumption.
Cost and weight increases are justi?ed by transmission length reduction,
sometimes necessary on transversal engines with large displacement and more
than four cylinders.
In all these gearboxes synchronizers are coupled to adjacent speeds (e.g.:
?rst with second, third with fourth, etc.) in order to reduce overall length and
to shift the two gears with the same selector rod.
We de?ne as the selection plane of a shift stick (almost parallel to the xz
coordin ate body reference system plane for shift lever on vehicle ?oor) the plane
on which the lever knob must move in order to select two close speed pairs. For
instance, for a manual gearbox following many existing schemes, ?rst, second,
third, fourth and ?fth speed are organized on three di?erent selection planes; the
reverse speed can have a dedicated plane or share its plane with the ?fth speed.
Figure 9.5 shows a typical example of a ?ve speed single stage gearbox. The
?rst speed wheels are close to a bearin g, in order to limit shaft de?ection.
In this gearbox the total number of tooth wheels pairs is the same as for
the double stage transmission shown in Fig. 9.6.
While in the ?rst gearbox there are only two gearing wheels for each speed,
in the second there are three gearing wheels for the ?rst four speeds and none
FIGURE 9.5. Scheme for a ?ve speed single stage transmission, suitable for front wheel
drive with transversal engine.432 9. MANUAL GEARBOXES
FIGURE 9.6. Scheme of an on-line double stage gearbox for a conventional lay-out.
for the ?fth. This property is produced by the presence of the so called constant
gear wheels (the ?rst gear pair at the left) that move the input wheels of the
?rst four speeds; the ?fth speed is a direct drive because the two p arts of the
upper shaft are joined together.
The single stage gearbox in Fig. 9.5 shows the ?fth speed wheel pair posi-
tioned beyond the bearing, witness to the upgrading of an existing four speed
transmission; in this case the ?fth speed has a dedicated selection plane.
The double stage gearbox in Fig. 9.7 is organized in a completely di?erent
way but also shows the ?rst speed pair of wheels close to the bearing. The direct
drive is dedicated to the highest speed; the ?fth speed shows a dedicated selectio n
plane.
Six speed double stage gearboxes do not show conceptual changes in com-
parison with the previous examples; synchronizers are organized to leave ?rst
and second, third and fourth, ?fth and sixth speeds on the same selection plane.
As already seen, the multistage con?guration shown in Fig. 9.7 allows a
reasonable reduction of the length of the gearbox. In this scheme, only ?rst and
second speeds bene?t from the second countershaft; power enters the counter-
shaft through a constant gear pair of whee ls and ?ows to the output shaft at a
reduced speed. Third, fourth and ?fth speed have a single stage arrangement.
Reverse speed is obtained with a conventional idling wheel.
9.3.2 Practical examples
Four speed gearboxes represented the most widely distributed solution in Europe
until the 1970s, with some economy cars having only three speeds.9.3 Manual automobile gearboxes 433
FIGURE 9.7. Scheme of a triple stage ?ve speed gearbox, suitable for front wheel driven
car with transversal engine.
With the increase in installed power, the improvement in aerodynamic per-
formance and increasing attention to fuel consumption, it became necessary to
increase the transmission ratio of the last speed, having the ?rst speed remain at
the same values; as a matter of fact car weight continued to increase and engine
minimum speed did not change signi?cantly.
To achieve satisfactory performance all manufacturers developed ?ve speed
gearboxes; this solution is now standard, but many examples of six speed gear-
boxes are available on the market, not limited to sports cars.
Figure 9.8 shows an example of a six speed double stage transmission with
the ?fth in direct drive; here the ?rst and second pair of wheels are close to the
bearing.
This rule is not generally accepted; on one hand having the most stressed
pairs of wheels close to the bearing allows a shaft weight containment. On the
other hand, having the most frequently used pairs of wheels close to the bearing
reduces the noise due to shaft de?ection.
Synchronizers of fourth and third speed are mounted on the countershaft;
this lay-out reduces the work of synchronization, improving shifting quality by an
amount proportional to the dimension of the synchronizing rings. Synchronizers
of ?rst and second gear on the output shaft are, because of their diameter, larger434 9. MANUAL GEARBOXES
FIGURE 9.8. Double stage six speed gearbox (GETRAG).
than those of the corresponding gear; the penalty of the synchronization work is
paid by the adoption of a double ring synchronizer.
Synchronizers on the countershaft o?er a further advantage: In idle position
the gears are stopped and produce no rattle; this subject will be studied later on.9.3 Manual automobile gearboxes 435
Figure 9.9 introduces the example of a single stage gearbox for a front
longitudinal engine. The input upper shaft must jump over the di?erential, which
is set between the engine and the wheels. The increased length of the shafts
suggested adopting a hollow section. Because of this length the box is divided
into two sections; on the joint between the two sections of the box additional
bearings are provided to reduce the shaft de?ection.
The input shaft features a ball bearing close to the engine and three other
needle bearings that manage solely the radial loads. The output shaft has two
tapered roller bearings on the di?erential side and a roller bearing on the opposite
side. This choice is justi?ed by the relevant axial thrust emerging from the bevel
gears.
The ?rst and second speed synchronizers are on the output shaft a nd feature
a double ring.
The reverse speed gears are placed immediately after the joint (the idler
gear is not visible) and have a synchronized shift. Remaining synchronizers are
set in the second section of the box on the input shaft. The output shaft ends
with the bevel pinion, a part of the ?nal ratio.
It should be noted that the gears of the ?rst, second and reverse speeds are
directly cut on the input shaft, in order to reduce overall dimensions.
Most contemporary cars use a front wheel drive with transversal engine; the
number of gearboxes with integral helical ?nal ratio is, therefore, dominant.
In these gearboxes geared pairs are mounted from the ?rst to the last speed,
starting from the engine side. An example of this architecture is given in Fig. 9.10.
Like many other transmissions created with only four speeds, it shows the
?fth speed segregated outside of the aluminium box and enclosed by a thin steel
sheet cover; this placement is to limit the transverse dimension of the power
train, in the area where there is potential interference with the left wheel in the
completely steered position.
This solution is questionable as far as the total length is concerned but shows
some advantage in the reduction of the span between the bearings. Each bearing
is of the ball type; on the side opposite to the engine the external ring of the
bearing can move axially, to compensate for thermal di?erential displacements.
One of the toothed wheels of the reverse speed is cut on the ?rst and second
shifting sleeve.
The casing is open on both sides; one of these is the rest of one of the
bearings of the ?nal drive. A large cover closes the casing on t he engine side and,
in the meantime, provides installation for the second bearing of the ?nal drive
and the space for the clutch mechanism; it is also used to join the gearbox to
the engine.
In this gearbox synchronizers are placed partly on the input shaft and partly
on the output shaft.
Figure 9.11 shows a drawing of a more modern six speed gearbox, in which
it was possible to install all the gears in a conventional single stage arrangement,
thanks to the moderate value of the rated torque.436 9. MANUAL GEARBOXES
FIGURE 9.9. Single stage six speed gearbox for longitudinal front engine (Audi).9.4 Manual gearboxes for industrial vehicles 437
FIGURE 9.10. Five speed transmission for a transversal front engine (FIAT).
Gears are arranged from the ?rst to the sixth, starting from the engine
side; as we have already said this arrangement is demanded by the objective
of minimizing shaft de?ection. Only the synchronizers of ?rst and second speed
found no place on the input shaft; they are of the double ring type, as for the
?rst speed.
The reverse speed is synchronized and bene?ts of a countershaft not shown
in this drawing.
9.4 MANUAL GEARBOXES FOR INDUSTRIAL
VEHICLES
9.4.1 Lay-out schemes
The gearboxes we are going to examine in this section are suitable for vehicles of
more than about 4 t of total weight; lighter vehicles, usually called commercial
vehicles, adopt gearboxes that are derived from automobile production, as noted
in the previous section.438 9. MANUAL GEARBOXES
FIGURE 9.11. Six speed transmission for a transversal front engine (FIAT).
Gearboxes used in industrial vehicles also feature synchronizers; they can be
shifted directly, as in a conventional manual transmission, or indirectly with the
assistance of servomechanisms. Non-synchronized gearboxes are sometimes used
on long haul trucks, because of their robustness. Assisted shifting mechanisms
are widespread because of the easy availability of power media. Automatic or
semi-automatic transmis sions are also used, the ?rst type especially in buses.
For gearboxes with four up to six speeds, the double stage countershaft
architecture represents a standard; the scheme is the same as seen before.
The constant gear couple is used for all speeds but the highest. Also notable
is that the lowest speed wheels are close to the bearings.
As shown in the drawings of Fig. 9.12, the highest speed can be obtained
either in direct drive (scheme b) or with a pair of gears (scheme a); in this last
case the direct drive is used for the speed before the last: these architectures are
called direct drive and overdrive.
In the ?gure, only the last and the ?rst before the last speed are represented.
The choice between the two alternatives can be justi?ed by the di?erent
vehicle mission; virtually the same gearbox can be used on di?erent vehicles
with di?erent frequently used speeds (a truck and a bus for example).9.4 Manual gearboxes for industrial vehicles 439
FIGURE 9.12. Alternative constant gear schemes with last or ?rst before the last speed
in direct drive.
Sometime the constant gear is set on the output shaft, after the di?erent
speed gears; this con?guration o?ers the following advantages:
?Reduction of the work of synchronization, because of the smaller gear di-
mension at the same torque and total transmission ratio
?Less stress on the input shaft and countershaft
On the other hand, the following disadvantages emerge:
?Bearings rotate faster.
?Constant gear wheels are more highly stressed.
This applies for single range transmissions.
Multiple range transmissions feature, in addition to the main gearbox, other
gearboxes that multiply the number of speeds of the main gearbox by the number
of their speeds. With this architecture the total number of gear pairs might be
reduced, for a given number of speeds, and, sometime the use of the gearshift
lever can be simpler.
This arrangement is used when more than six speeds are necessary. A multi-
ple range transmission is therefore made out of a combination of di?erent coun-
tershaft gearboxes, single range gearboxes or epicycloidal gearboxes.
Each added element is called a range changer if it is conceived as being
capable of using the main gearbox speeds in sequence, in two completely non-
overlapping series of vehicle speeds; for example, if the main gearbox has four
speeds, the ?rst speed in the high range is faster than the fourth speed in the
low range.
The element is called a splitter if it is intended to create speeds that are
intermediate to those of the main gearbox; in this case, for example the third440 9. MANUAL GEARBOXES
FIGURE 9.13. Scheme of a 16 speed gearbox for industrial vehicles; it is made with a
four gear main gearbox, a double speed splitter and a double speed range changer with
direct drive.
speed in the high range is faster than the third speed in the low range, but slower
than the fourth speed in the low range.
We call the gearbox with the highest number of speeds the main gearbox;
the splitter and the range changer will be set in series before and after the main
gearbox.
Figure 9.13 shows the scheme of a gearbox featuring a splitter and a range
changer. The splitter is made out of a pair of wheels that work as two di?erent
constant gears for the main gearbox. The countershaft can therefore be moved
at two di?erent speeds, according to the position of the splitter unit. Because
the main gearbox has four speeds, this splitter unit can create a total of eight
speeds, one of them being in direct drive.
At the output shaft of this assembly, there is a range changer unit made
as a two speed double stage gearbox with direct drive; this unit multiplies by
two the total number of obtainable speeds. The range changer is quali?ed by the signi?cant di?erence between the two obtainable speeds.
The range changer can be made with a countershaft gearbox or an epicy-
cloidal gearbox with direct drive; the advantage in the latter case is the possi-
bility of an easier automatic actuation, by braking some of the elements of the epicycloidal gear.9.4 Manual gearboxes for industrial vehicles 441
FIGURE 9.14. Transmission ratios obtained with the scheme of transmission shown in Fig. 9.15; speed identi?cation shows the main gearbox speed with the number, the splitter position with the ?rst letter, the range changer position wi th the second; L stands for low, H stands for high.
It is also possible to place the range changer before the main gearbox and
the splitter unit after the main gearbox.
A di?erent way of de?ning the functions of range change units is to say that
the splitter is a gearbox that compresses the gear sequence, because it reduces
the gap between speeds, while the range changer is a gearbox that expands the gear sequence, because it increases the total range of the transmission.
Figure 9.14 explains the concept of compression; the bars represent the ratios obtained in all shifting lever positions. Ratios obtained with the splitter unit in
the L position (the ?rst letter in the speed identi?cation, L stands for lower ratio) are interspersed with the ratios obtained with the splitter unit in the H position (H stands for higher ratio, in this case 1:1) and reduce the amplitude of the gear steps of the main gearbox.
The same ?gure also explains the concept of expansion, showing on the
same graph the ratio obtained with the range changer in the H position (second identi?cation letter) and the L position; the gear step between the ?rst in low
gear and the ?rst in high gear is as big as the range of the main gearbox, and
the total transmission range is widened.
The range changer is therefore seldom used, when driving conditions change suddenly, as, for example, when leaving a normal road for a country road that must be driven more slowly, or when encountering a strong slope with a fully loaded vehicle. The splitter allows the dynamic performance of the vehicle to be improved, making the optimum transmission ratio available to obtain the desired power. The splitter is therefore used frequently. In a fully loaded vehicle, for example, all split ratios can be used in sequence during full throttle acceleration from a standstill.442 9. MANUAL GEARBOXES
The range changer and splitter are usually made as modular units that can
be mounted at both ends of the main gearbox, or changed with simple covers,
in order to satisfy all application needs with limited total production costs. Generalizing these concepts could suggest building transmissions using ad- ditional range changing units arranged in series. These could be conceived as being made only of splitter units with direct drive.
In such a case, with n pairs of tooth wheels it is possible to obtain a total
of z transmission ratios, given by the formula:
z =2n?1
. (9.1)
The formula expresses the number of possible states that can be obtained
from n ? 1 pairs of gears; one unit is subtr acted because one pair must be a constant gear to move the countershaft.
With four pairs of gears, for example, four speeds can be obtained in a
double stage gearbox; while using a cascade of splitters eight di?erent speeds could be obtained. The goal of good shift manoeuvrability and the implications
for mechanical losses must not be forgotten, while de?ning the best architecture. Figure 9.15 shows the scheme of the 16 speed transmission with splitter and
range changer we already described. In this picture are represented the spans of
shafts under torque; the dotted line shows where upper input and output shafts
are loaded, while the solid line shows when the lower countershaft is loaded. The
two lines are joined where a pair of wheels is gearing.
A totally di?erent approach is shown by the double countershaft transmis-
sion in Fig. 9.16 (Fuller scheme); the power ?ow is divided between two coun-
tershafts by two constant gears and exits through a single output shaft. This
con?guration has been conceived wit h the objective of shortening the gearbox,
because it is possible, in this way, to divide the torque on two gear wheels work-
ing in parallel. The teeth width can be reduced by about 40% at the same level
of rated torque.
On the other hand the transmission is much wider; this choice can represent
a favorable compromise for certain vehicles such as road saddle tractors.
In this scheme, after the main gearbox, there is a three speed splitter; one
splitter speed is direct drive, one is over-drive, the last is under-drive; the total
number of speeds is therefore 12.
It can be noticed that the reverse speed is obtained with the same wheels
used for the ?rst speed and with two small idlers. With this arrangement it is
also possible to use the splitter in reverse speed.
9.4.2 Practical examples
A practical example of a gearbox for a medium duty truck is shown in Fig. 9.17;
in this example a double stage four speed main gearbox is joined to a two speed
splitter, o?ering a total of eight speeds. The splitter unit with its direct drive9.4 Manual gearboxes for industrial vehicles 443
FIGURE 9.15. Power ?ow scheme in the 16 speeds of a gearbox; lines are dotted when
the torque ?ows through the countershaft. They are solid when the torque ?ows through
the upper shafts (input and output shafts).
FIGURE 9.16. Scheme of a Fuller gearbox featuring 12 speeds, created from a main
four speed double countershaft gearbox and a splitter gearbox with three speeds; one of
these last is direct drive. The two countershafts in the main gearbox and in the splitter
allow the gear wheel width and therefore the total length of the gearbox to be reduced.444 9. MANUAL GEARBOXES
FIGURE 9.17. Truck gearbox with eight speeds; on the lower side there is the reverse
idler (IVECO).9.4 Manual gearboxes for industrial vehicles 445
FIGURE 9.18. Truck gearbox with 16 speeds including splitter and range changer (IVECO).446 9. MANUAL GEARBOXES
FIGURE 9.19. Fuller gearbox (IVECO).
can obtain the same transmission ratios as the main gearbox, while a reduced
speed can obtain transmission ratios that are set between the ratios of the main
gearbox.
Section A-A on the lower right side shows a detail of the idler of the reverse
speed; the reverse speed is doubled by the splitter.9.4 Manual gearboxes for industrial vehicles 447
In the main gearbox the wheels of the ?rst and reverse speeds are close to
the rear bearing; the wheels of the following speeds are set in increasing order
from the left to the right. The eighth speed is direct drive.
The synchronizers of the ?rst and second speed show a double ring, while the
reverse speed has no synchronization. This gearbox can receive a conventional
manual shifting mechanism or a power assisted mechanism that can be fully
automatic.
A three element gearbox with a total of 16 speeds is shown in Fig. 9.18. A
four speed main gearbox (the same as in the previous example) is joined with
a two speed splitter and a two speed range changer. The wheels in the main
gearbox are ordered in increasing speed from the rear bearing.
The 16th gear is a direct drive. The range changer is made with epicycloidal
gears; when the rear shifting sleeve is moved to the left, the epicycloidal gear is blocked and acts like a locked joint.
When the rear shifting sleeve is moved to the right the annulus wheel is
blocked with the casing and the carrier speed will be reduced, with the same direction of the input speed.
The reduced speeds stay in a range that is fully separated from the normal speed range; they will be used when a very high torque or a very low speed are needed. The main gearbox shows ball bearings and tapered roller bearings, while the epicycloidal gear train, where the radial thrusts are self-equilibrated, shows only needle bearings and a ball bearing.
The main gearbox countershaft rotates also in idle speed; it shows a spline
end that can be used to move auxiliary equipments such as a hydraulic pump useful to operate a tilting loading plane.
A practical example of the Fuller scheme is shown in Fig. 9.19; in this ex-
ample the gearbox has a total of 16 speeds and is made of a four speed main gearbox, a two speed splitter and a two speed range epicycloidal gear changer. Notice the two reverse speed idlers. The splitter shift is synchronized, while
the main gearbox features dog clutches.
Gear shifts are semi-automatic, manually pre-selected; in this case the gear
shift lever does not move the shifting sleeves mechanically, but launches an auto- matic sequence, where electric valves operate pneumatic actuators. The selection and shift motions do not occur when the lever is moved but when the power is cut o? because the accelerator pedal is released or the clutch pedal is depressed
吉林化工学院外文翻译
手动变速箱
MANUAL GEARBOXES
性质: 毕业设计□毕业论文
教学院：机电工程学院
系别：机械设计制造及其自动化学生学号：09410235
学生姓名：韩东君
专业班级：机自0902
指导教师：
职称：
起止日期：2013.3.4～2013.3.20
吉林化工学院
Jilin Institute of Chemical Technology
手动变速箱
1.手动变速箱分类
变速箱的分类通常根据参与传输运动齿轮的数目。在手动汽车变速箱的情况下，只考虑前进的速度，不考最终的传动齿轮，即使它被包含在变速箱内。因此有单级齿轮箱、双级或副轴齿轮箱、多级齿轮箱。图1.1显示了三种配置的四速变速箱。
对这些采用普遍规则的评论是很有用的，每个齿轮被分割很多段，其螺距与齿轮的直径成正比。该段最后的水平行程，代表牙宽度。如果该段被交叉轴中断，则该齿轮处于闲置状态，否则该段超越了轴的承受界限没有中断。然后根据中心相同的规则，齿轮与轴一起旋转。而套筒代表了一对水平行程，箭头显示输入轴和输出轴的方向。单级齿轮箱主要应用于前轮驱动的车辆，因为这些输入和输出轴容易被抵消。
图1.1传统车辆的四速变速箱分三个不同的配置:单级，两级和三级。另一方面，输入和输出轴要对齐这样更好。这就是为什么后轮驱动的车辆通常采用两级齿轮箱，而在前轮驱动的车辆采用多级配置是与横向引擎。因为变速箱的横向长度可以缩短，速度的大小或齿轮的宽度不允许一个单级传动被使用。应该指出的是,前轮驱动的车辆采用横向引擎是由前轮距和轮胎的尺寸所决定的。齿轮箱的长度直接影响着方向盘的最大转向角与最小转弯半径。多级齿轮箱上的横向维度的积极作用可抵消较高的机械损失，但将导致啮合齿轮的数量增加。
应该指出的是,在三阶段变速箱,如图中所示该计划表现出，这个图中的三个轴不处于同
一平面。在侧视图中，三个轴的轮廓应表示为一
个三角形的顶点，这将减少变速箱的横向尺寸。
除了这种与其他情况，我们会在之后介绍，这个
图代表的是，输入轴平面和副轴平面上的中间轴
与输出轴。齿轮传动通常采用的反速度进行区分，
反转的速度是通过使用一个附加的齿轮实现的。
事实上，上述的三个齿轮，输出速度方向与输入
速度方向相同。而其他列的两个齿轮只有一个与
输出速度的方向相反，增加齿轮通常被称为惰轮。
主要的配置在图1.2中，在方案中，增加一个
副轴显示一个滑动滚轮，可配合两个啮合的齿轮不接触。例如，输入齿轮的第一速度和输出齿轮的第二速度。应该指出的是，在这个方案中，图纸不保持零件的实际尺寸。
图1.2用于反向速度。这样的计划适合所有类型的变速箱，方案b显示两个相反的滑动惰轮一起转动。在一个给定的传动比下这样的安排提供了额外的自由度，中间轴偏离绘图平面，箭头显示齿轮匹配啮合的反向速度。方案c是类似于一个相对的惰轮，当它在怠速位置对特定轮的输出轴与齿轮，将减少移动套筒的第一和第二速度。配置d显示了一对专用的齿轮，带着一个惰轮和一个连接套筒。配置图中所示的是以下的优点和缺点。方案A，B和C比较简单，但排除同步中的应用他们也不允许使用斜齿轮。方案d更复杂,但是可以包括一个同步器,可以采用斜齿轮，方案A，B和C不增加变速箱长度。
2. 机械效率
相比其他机构完成同一功能，汽车的齿轮传动的机械效率高。事实上，这种效率的价值不可忽视性能计算和燃油消耗。变速箱设计师不断的努力来限制燃料消耗以减少机械损失，总的传输损耗输送条件，都依赖于独立的处理能力。
首要条件:
（1）传动损失：这些是由啮合齿之间产生的摩擦和齿轮在空气与油旋转产生的摩擦造成的。
（2）轴承损失：这些是由于滚动体的变形，接触面积的扩展，在空气和油中旋转造成的。（3）密封损失：它们之间产生的摩擦是由于密封件和旋转轴的动力独立造成的。
（4）润滑损失：如果存在，这些是由润滑泵动力独立产生的。
所有这些损失取决于接触部分的旋转速度和发动机转速与选定的传动比。表2.1报告采取的计算应考虑节气门全开条件下的机械效率，这些参考值将伴随一对飞溅润滑的传动齿轮或一个完整的传输的过程。在相同的表中我们还可以看到，一个完整的动力换档外摆线，及其汽车的电气自动传输方式和钢带无级变速传动。对于最后两个传输，液力变矩器必须被锁紧。
表2.1不同传输机制的机械效率
机制类型效率（%）
采用飞溅润滑的完整手动变速箱 92-97
全自动变速器 90-95
全自动变速箱（钢带，没有压力控制） 70-80
全自动变速箱（钢带，有压力控制） 80-86
圆柱齿轮副 90.0-90.5
锥齿轮副 90-93
表2.2机械效率
上图为输入速度300NM的单级变速箱设计总摩擦损失。作为旋转输入速度函数，而不追求效率，这是更正确的参考功率损耗量。上图为一个二级传动的例子，四个最大功率的速度对整体不同的贡献。这种测量采用一步一步拆卸变速箱的方式，从而消除相关的损失。所有同步环在第一步骤中被除去，只留下的同步器的中心。因此，非啮合的同步器的机械损失可测量。该损失是由于非从事润滑圆锥表面的相对速度不同造成的，这一损失的价值将决定速度和选择的传动比。在第二步骤中除去所有的旋转密封，在第三步去除润滑油，因此消除了大部分润滑损失。但是必须残留一些油，为了使接触齿之间分离不受影响。通过去除那些不参与动力传动的齿轮，机械损失可被测出。其余的损失是由于轴承和先前去除的部分造成的。更详尽的方法在于测量完整的效果图，其中两个坐标分别代表输入速度和发动机转矩效率。这样效率就可以表示为表面的第三坐标，它可以通过比较输入和输出扭矩的工作传输计算得出。这样的效果图显示出在合适的输入转矩下，效率达到一个几乎恒定的值。不要忘记，对燃料消耗标准周期的作用，适中的扭矩会使传输效率和扭矩值发生变化。
图2.3显示了上述在恒定的发动机转速下定性截面图
机械效率图2.3表示，在输入扭矩保持恒定的前提下发动机转速，虚线代表的是一个合理的近似的曲线，该曲线用于建立数学模型，对性能和燃油消耗量进行预测。事实上，转矩值略大于零，摩擦意味着一定程度上不可能低于输入转矩的最小值。一个好的近似代表机械效率曲线可以通过使用这个虚线，插入真实曲线达到共同表示的目的。
3.汽车手动变速箱
采用的方案：手动变速箱速度的变化和离合器的啮合与脱开仅由驱动力决定。这种变速箱是由螺旋齿轮和同步器共同组成的。特别是在经济型车上，变速箱不使用显示反向速度的同步器。我们前面所讨论的为第一类，速度的大小是额外的信息，通常在四到六之间。
单级齿轮箱中常使用反向轴，但是有一些例外。前轮驱动前置发动机和后轮驱动后置发动机的汽车，它们有横向和纵向发动机。在所有这些情况下，由于最后的驱动器包含在变速箱内，因此也被称为传输。驱动汽车常用副轴变速箱，发动机纵向安装在前轴和后桥驱动轴上。如果为了改善重量分布，齿轮箱应安装在后桥上，最后的驱动器也可以包含在变速箱内。
通过多级变速器，一些齿轮可用于输出不同的速度。通常在速度较低的情况下，增加轮子的数量可能会增加一些传动速度。因为不经常使用这样的速度，会降低了机械效率，从而减少了燃料的消耗。同时成本和重量的增加导致传输长度的减少，有时有必要采用超过四个汽缸的大排量横向发动机。通过同步器的耦合使这些变速箱与相邻的速度相同，以降低变速箱总的长度同时采用同一个操控杆变换两个齿轮。通过旋杆的移动选择两个相近的速度，我们定义为变速杆选择平面。例如，一个手动变速箱有许多现有的计划，用三个不同的选择平面控制一二三四五个不同的速度，其中反向速度可以用一个专门的平面或共享刚才五速的平面。
图3.1显示了一个典型的例子,一个五速单级齿轮箱。为了限制轴偏转，第一个齿轮的速度与轴承的速度很接近。该变速箱齿轮副的
总数与图3.1中二级传动的齿轮副数相同。在
第一变速箱中只有两个传动齿轮，第二个变
速箱有三个齿轮为第一个变速箱提供四种速
度。图3.1为五速单级传动方案，适用于前轮
驱动并配有横置发动机的汽车。
图3.2为常规布置的双级变速箱，是由恒
定的齿轮数所决定的。使前轮具有前四种速
度，第五种速度是直接驱动的，因为这两个
部分是由轴连接在一起的。在图3.1单级齿轮
箱中，第五个齿轮的速度比轴承快，是现有
的四档变速器的一个升级。双级变速箱的组
织结构和单级的完全不同，同时也说明了第一
对齿轮的速度与轴承是比较接近的，并且直接
驱动以达到最高速度。六速双级变速箱与之前
的例子没有本质上的的改变，同步装置使一二
三四五六级速度在同一个平面上。
正如已经看到的，在多级配置中允许合理
的减少变速箱的长度。在这个方案中，只有一
级和二级的速度优于副轴。动力通过车轮不断
进入副轴齿轮副，使输出轴保持一个较低的速度。三级，四级，五级有单级的分布，反向速度由传统的空转轮得到。
中英文对照外文翻译 汽车变速器设计 我们知道，汽车发动机在一定的转速下能够达到最好的状态，此时发出的功率比较大，燃油经济性也比较好。因此，我们希望发动机总是在最好的状态下工作。但是，汽车在使用的时候需要有不同的速度，这样就产生了矛盾。这个矛盾要通过变速器来解决。 汽车变速器的作用用一句话概括，就叫做变速变扭，即增速减扭或减速增扭。为什么减速可以增扭，而增速又要减扭呢？设发动机输出的功率不变，功率可以表示为 N = w T，其中w是转动的角速度，T 是扭距。当N固定的时候，w与T是成反比的。所以增速必减扭，减速必增扭。汽车变速器齿轮传动就根据变速变扭的原理，分成各个档位对应不同的传动比，以适应不同的运行状况。 一般的手动变速器内设置输入轴、中间轴和输出轴，又称三轴式，另外还有倒档轴。三轴式是变速器的主体结构，输入轴的转速也就是发动机的转速，输出轴转速则是中间轴与输出轴之间不同齿轮啮合所产生的转速。不同的齿轮啮合就有不同的传动比，也就有了不同的转速。例如郑州日产ZN6481W2G型SUV车手动变速器，它的传动比分别是：1档3.704:１；2档2.202:1；3档1.414:1；4档1:1；5档（超速档）0.802:1。 当汽车启动司机选择1档时，拨叉将1/2档同步器向后接合1档
齿轮并将它锁定输出轴上，动力经输入轴、中间轴和输出轴上的1档齿轮，1档齿轮带动输出轴，输出轴将动力传递到传动轴上（红色箭头）。典型1档变速齿轮传动比是3:1,也就是说输入轴转3圈，输出轴转1圈。 当汽车增速司机选择2档时，拨叉将1/2档同步器与1档分离后接合2档齿轮并锁定输出轴上，动力传递路线相似，所不同的是输出轴上的1档齿轮换成2档齿轮带动输出轴。典型2档变速齿轮传动比是2.2:1，输入轴转2.2圈，输出轴转1圈，比1档转速增加，扭矩降低。 当汽车加油增速司机选择3档时，拨叉使1/2档同步器回到空档位置，又使3/4档同步器移动直至将3档齿轮锁定在输出轴上，使动力可以从轴入轴—中间轴—输出轴上的3档变速齿轮，通过3档变速齿轮带动输出轴。典型3档传动比是1.7:1，输入轴转1.7圈，输出轴转1圈，是进一步的增速。 当汽车加油增速司机选择4档时，拨叉将3/4档同步器脱离3档齿轮直接与输入轴主动齿轮接合，动力直接从输入轴传递到输出轴，此时传动比1:1，即输出轴与输入轴转速一样。由于动力不经中间轴，又称直接档，该档传动比的传动效率最高。汽车多数运行时间都用直接档以达到最好的燃油经济性。 换档时要先进入空档，变速器处于空档时变速齿轮没有锁定在输出轴上，它们不能带动输出轴转动，没有动力输出。 一般汽车手动变速器传动比主要分上述1－4档，通常设计者首先确定最低（1档）与最高（4档）传动比后，中间各档传动比一
On the vehicle sideslip angle estimation through neural networks: Numerical and experimental results. S. Melzi,E. Sabbioni Mechanical Systems and Signal Processing 25 (2011)：14~28 电脑估计车辆侧滑角的数值和实验结果 S.梅尔兹,E.赛博毕宁 机械系统和信号处理2011年第25期：14~28
摘要 将稳定控制系统应用于差动制动内/外轮胎是现在对客车车辆的标准（电子稳定系统ESP、直接偏航力矩控制DYC）。这些系统假设将两个偏航率(通常是衡量板)和侧滑角作为控制变量。不幸的是后者的具体数值只有通过非常昂贵却不适合用于普通车辆的设备才可以实现直接被测量,因此只能估计其数值。几个州的观察家最终将适应参数的参考车辆模型作为开发的目的。然而侧滑角的估计还是一个悬而未决的问题。为了避免有关参考模型参数识别/适应的问题,本文提出了分层神经网络方法估算侧滑角。横向加速度、偏航角速率、速度和引导角,都可以作为普通传感器的输入值。人脑中的神经网络的设计和定义的策略构成训练集通过数值模拟与七分布式光纤传感器的车辆模型都已经获得了。在各种路面上神经网络性能和稳定已经通过处理实验数据获得和相应的车辆和提到几个处理演习(一步引导、电源、双车道变化等)得以证实。结果通常显示估计和测量的侧滑角之间有良好的一致性。 1 介绍 稳定控制系统可以防止车辆的旋转和漂移。实际上，在轮胎和道路之间的物理极限的附着力下驾驶汽车是一个极其困难的任务。通常大部分司机不能处理这种情况和失去控制的车辆。最近,为了提高车辆安全，稳定控制系统(ESP[1,2]; DYC[3,4])介绍了通过将差动制动/驱动扭矩应用到内/外轮胎来试图控制偏航力矩的方法。 横摆力矩控制系统（DYC）是基于偏航角速率反馈进行控制的。在这种情况下,控制系统使车辆处于由司机转向输入和车辆速度控制的期望的偏航率[3,4]。然而为了确保稳定，防止特别是在低摩擦路面上的车辆侧滑角变得太大是必要的[1,2]。事实上由于非线性回旋力和轮胎滑移角之间的关系，转向角的变化几乎不改变偏航力矩。因此两个偏航率和侧滑角的实现需要一个有效的稳定控制系统[1,2]。不幸的是,能直接测量的侧滑角只能用特殊设备(光学传感器或GPS惯性传感器的组合)，现在这种设备非常昂贵,不适合在普通汽车上实现。因此, 必须在实时测量的基础上进行侧滑角估计，具体是测量横向/纵向加速度、角速度、引导角度和车轮角速度来估计车辆速度。 在主要是基于状态观测器/卡尔曼滤波器(5、6)的文学资料里, 提出了几个侧滑角估计策略。因为国家观察员都基于一个参考车辆模型,他们只有准确已知模型参数的情况下，才可以提供一个令人满意的估计。根据这种观点,轮胎特性尤其关键取决于附着条件、温度、磨损等特点。 轮胎转弯刚度的提出就是为了克服这些困难,适应观察员能够提供一个同步估计的侧滑角和附着条件[7,8]。这种方法的弊端是一个更复杂的布局的估计量导致需要很高的计算工作量。 另一种方法可由代表神经网络由于其承受能力模型非线性系统，这样不需要一个参
附录 附录A Braking system function is to make the car driving in accordance with the requirements of the pilot required even slow down park; They offend car has in various road conditions (including in the slope stability) in car; Make the downhill cars speed to be stable. For car up the role of brake is only in the car and role with the direction of the car driving direction opposite forces, and the size of these forces are random, do not control, so cars must be installed on a series of special equipment to achieve the function. Automobile brake system is to point to to ensure that the car in technology, improve the safe driving car average speed, etc., and the admiration installed in the car brake special brake institutions. In general automobile brake system including crane brake system and parking brake two sets of independent device. One crane brake device is a driver with feet to manipulate, and it said the foot brake. Parking brake device is a pilot with the hand, so it says of the manipulation of the hand brake. The function of the crane brake system is to make the car slow down or running in the shortest distance parking within. And parking brake function is to make had stopped the car on the road all keep still. But, sometimes, in an emergency, two braking device can be used at the same time and increase the effect of auto brake. Some special purpose of cars and often in the mountains cars, long and frequently brake will lead to crane brake system overheating, so in these cars often add all sorts of different types of auxiliary braking equipment, so as to speed up the hill stability. According to the braking energy situation, brake system can also be divided into human brake system, power brake system, and servo brake system, three. Human brake system to the driver's physical strength as braking energy; Power brake system engine power to the transformation of the air pressure or hydraulic braking energy as; And servo brake system is the most human and engine power as a brake energy. In addition, according to the braking energy transfer mode, brake system and can be divided into mechanical and hydraulic, pneumatic type and assolenoid style wait until a few kinds.
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 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 development of automobile As the world energy crisis and the war and the energy consumption of oil -- and are full of energy in one day someday it will disappear without a trace. Oil is not inresources. So in oil consumption must be clean before finding a replacement. With the development of science and technology the progress of the society people invented the electric car. Electric cars will become the most ideal of transportation. In the development of world each aspect is fruitful especially with the automobile electronic technology and computer and rapid development of the information age. The electronic control technology in the car on a wide range of applications the application of the electronic device cars and electronic technology not only to improve and enhance the quality and the traditional automobile electrical performance but also improve the automobile fuel economy performance reliability and emission spurification. Widely used in automobile electronic products not only reduces the cost and reduce the complexity of the maintenance. From the fuel injection engine ignition devices air control and emission control and fault diagnosis to the body auxiliary devices are generally used in electronic control technology auto development mainly electromechanical integration. Widely used in automotive electronic control ignition system mainly electronic control fuel injection system electronic control ignition system electronic control automatic transmission electronic control ABS/ASR control system electronic control suspension system electronic control power steering system vehicle dynamic control system the airbag systems active belt system electronic control system and the automatic air-conditioning and GPS navigation system etc. With the system response the use function of quick car high reliability guarantees of engine power and reduce fuel consumption and emission regulations meet standards. The car is essential to modern traffic tools. And electric cars bring us infinite joy will give us the physical and mental relaxation. Take for example automatic transmission in road can not on the clutch can achieve automatic shift and engine flameout not so effective improve the driving convenience lighten the fatigue strength. Automatic transmission consists mainly of hydraulic torque converter gear transmission pump hydraulic control system electronic control system and oil cooling system etc. The electronic control of suspension is mainly used to cushion the impact of the body and the road to reduce vibration that car getting smooth-going and stability. When the vehicle in the car when the road uneven road can according to automatically adjust the height. When the car ratio of height low set to gas or oil cylinder filling or oil. If is opposite gas or diarrhea. To ensure and improve the level of driving cars driving stability. Variable force power steering system can significantly change the driver for the work efficiency and the state so widely used in electric cars. VDC to vehicle performance has important function it can according to the need of active braking to change the wheels of the car car motions of state and optimum control performance and increased automobile adhesion controlling and stability. Besides these appear beyond 4WS 4WD electric cars can greatly improve the performance of the value and ascending simultaneously. ABS braking distance is reduced and can keep turning skills effectively improve the stability of the directions simultaneously reduce tyre wear. The airbag appear in large programs protected the driver and passengers safety and greatly reduce automobile in collision of drivers and passengers in the buffer to protect the safety of life. Intelligent electronic technology in the bus to promote safe driving and that the other functions. The realization of automatic driving through various sensors. Except some smart cars equipped with multiple outside sensors can fully perception of information and traffic facilities
Automobile Brake System The braking system is the most important system in cars. If the brakes fail, the result can be disastrous. Brakes are actually energy conversion devices, which convert the kinetic energy (momentum) of the vehicle into thermal energy (heat).When stepping on the brakes, the driver commands a stopping force ten times as powerful as the force that puts the car in motion. The braking system can exert thousands of pounds of pressure on each of the four brakes. Two complete independent braking systems are used on the car. They are the service brake and the parking brake. The service brake acts to slow, stop, or hold the vehicle during normal driving. They are foot-operated by the driver depressing and releasing the brake pedal. The primary purpose of the parking brake is to hold the vehicle stationary while it is unattended. The parking brake is mechanically operated by when a separate parking brake foot pedal or hand lever is set. The brake system is composed of the following basic c omponents: the “master cylinder” which is located under the hood, and is directly connected to the brake pedal, converts driver foot’s mechanical pressure into hydraulic pressure. Steel “brake lines” and flexible “brake hoses” connect the master cylinder to the cylinders” located at each wheel. Brake fluid, specially designed to work in extreme conditions, fills the system. “Shoes” and “pads” are pushed by cylinders to contact the “drums” and “rotors” thus causing drag, which (hopefully) slows the car. The typical brake system consists of disk brakes in front and either disk or drum brakes in the rear connected by a system of tubes and hoses that link the brake at each wheel to the master cylinder (Figure).
外文翻译 文章出处《Tribology International》, 2009, 42(5):714-723 译文： 有限元热分析的陶瓷离合器 1 引言 磨料空转车辆离合器是力封闭联轴器。扭矩和高速传输被压紧表面之间产生的摩擦力所保证。应用陶瓷是因为它作为摩擦介质具有好耐热和耐磨损性能，提供了机会以驱动更高的压力，以及一个低的密度。因此，一个提功率密度启用了一个平行的最小化建筑空间。 测量使用陶瓷饰面离合器盘的第一个原型在卡尔斯鲁厄大学的一个实验室专门从事客车驱动系统进行了测试执行。在分析过程中的有限元（FE）模型是将与测量数据和测量条件的知识所构成。计算的目的是要确定在离合器盘上温度的分布以及环境中的在每一时刻的及时测量目。至关重要的是熟悉的温度范围，为了检验该系统的耐磨特性。因此，重要信息从测量数据中得出。在临界负载的情况下，预计最高温度必须在时间和空间上进行预测，为保护接近发热体的位置测量工具的。 本研究的目的是分析和修改该离合器系统通过改进，以提供更好的工作条件热传导和系统或增加转化成摩擦热的能量的对流。此外，人们希望找到更有效的更好的离合器系统设计方案。 计算是由宇宙星空的设计的软件进行的。在模型开发阶段，非常谨慎，必须采取几何元素，选择适当的简化尺寸，并且由于正确调整的时间步长大量的硬件要求瞬态计算。热物性参数的改变，如表面热对流化系数和热负荷，必须考虑到到在一个持续的基础上在时间和地点方面。离合器系统的分析测试这两方面，只能通过加热隔板连接的两个独立的模型来管理，根据该假说认为，接触温度必须是在两个相同的双方，同时他们要有适当接触，其价值需通过迭代来进行调整。计算显示，该热分区按周期变化，它沿不同的内，外接触环。在不同的冷却特性下，在陶瓷和钢之间的结果是不同的，热流从陶瓷侧面向钢侧流动。此热流也通过迭代确定;它的价值也改变了周期和不同沿着所述内和外接触环。 2 采用工程陶瓷作为摩擦材料的第一个原型机 这款检查过的离合器盘是根据“特定的陶瓷”产品而开发的，此材料的研发过程在流程在卡尔斯鲁厄大学的Institute for Product Development (IPEK)杂志上发表过。此开发过程已经具有的可能性，用于连接到一个真实的传动轴；甚至，它为面板有一个好的初始行为起到一个很好的缓冲作用。磨料配件必须符合以下基本要求：
汽车保险中英文对照外文翻译文献(文档含英文原文和中文翻译)
汽车保险 汽车保险是在事故后保证自己的财产安全合同。尽管联邦法律没有强制要求，但是在大多数州（新罕布什和威斯康星州除外）都要求必须购买汽车保险；在各个州都有最低的保险要求。在鼻腔只购买汽车保险的两个州，如果没有足够的证据表明车主财力满足财务责任法的要求，那么他就必须买一份汽车保险。就算没有法律规定，买一份合适的汽车保险对司机避免惹上官和承担过多维修费用来说都是非常实用的。 依据美国保险咨询中心的资料显示，一份基本的保险单应由6个险种组成。这其中有些是有州法律规定，有些是可以选择的，具体如下： 1.身体伤害责任险 2.财产损失责任险 3.医疗险或个人伤害保护险 4.车辆碰撞险 5.综合损失险 6.无保险驾驶人或保额不足驾驶人险 责任保险 责任险的投保险额一般用三个数字表示。不如，你的保险经纪人说你的保险单责任限额是20/40/10，这就代表每个人的人身伤害责任险赔偿限额是2万美元，每起事故的热身上海责任险赔偿限额是4万美元，每起事故的财产损失责任险的赔偿限额是1万美元。 人身伤害和财产损失责任险是大多数汽车保险单的基础。要求汽车保险的每个州都强令必须投保财产损失责任险，佛罗里达是唯一要求汽车保险但不要求投保人身伤害责任险的州。如果由于你的过错造成了事故，你的责任险会承担人身伤害、财产损失和法律规定的其他费用。人身伤害责任险将赔偿医疗费和误工工资；财产损失责任险将支付车辆的维修及零件更换费用。财产损失责任险通常承担对其他车辆的维修费用，但是也可以对你的车撞坏的灯杆、护栏、建筑物等其他物品的损坏进行赔偿。另一方当事人也可以决定起诉你赔偿精神损失。
毕业设计（论文）外文文献翻译 文献、资料中文题目：汽车制动系统 文献、资料英文题目： 文献、资料来源： 文献、资料发表（出版）日期： 院（部）： 专业：汽车检测与维修 班级： 姓名： 学号： 指导教师： 翻译日期： 2017.02.14
Automobile Brake System The braking system is the most important system in cars. If the brakes fail, the result can be disastrous. Brakes are actually energy conversion devices, which convert the kinetic energy (momentum) of the vehicle into thermal energy (heat).When stepping on the brakes, the driver commands a stopping force ten times as powerful as the force that puts the car in motion. The braking system can exert thousands of pounds of pressure on each of the four brakes. Two complete independent braking systems are used on the car. They are the service brake and the parking brake. The service brake acts to slow, stop, or hold the vehicle during normal driving. They are foot-operated by the driver depressing and releasing the brake pedal. The primary purpose of the brake is to hold the vehicle stationary while it is unattended. The parking brake is mechanically operated by when a separate parking brake foot pedal or hand lever is set. The brake system is composed of the following basic components: the “master cylinder” which is located under the hood, and is directly connected to the brake pedal, converts driver foot’s mechanical pressure into hydraulic pressure. Steel “brake lines” and flexible “brake hoses” connect the master cylinder to the “slave cylinders” located at each wheel. Brake fluid, specially designed to work in extreme conditions, fills the system. “Shoes” and “pads” are pushed by the slave cy linders to contact the “drums” and “rotors” thus causing drag, which (hopefully) slows the car. The typical brake system consists of disk brakes in front and either disk or drum brakes in the rear connected by a system of tubes and hoses that link the brake at each wheel to the master cylinder (Figure). Basically, all car brakes are friction brakes. When the driver applies the
外文翻译 Auto Transmission First, an overview of automotive transmission and the development trend Automobile available more than a century, especially from the mass production of motor vehicles and the automotive industry since the development of large, Car has been the economic development of the world for mankind to enter the modern life and have had a tremendous impact on the immeasurable, The progress of human society has made indelible contributions to the great, epoch-making set off arevolution. From From the vehicle as a power plant using internal combustion engine to start, auto transmission has become an important component. Is Generation is widely used in automotive reciprocating piston internal combustion engine with a small size, light weight, reliable operation and the use of The advantages of convenience, but its torque and speed range of smaller changes, and complex condition requires the use of motor vehicles Traction and the speed can be considerable changes in the scope. Therefore, its performance and vehicle dynamics and economy of There are large inter-contradictions, which contradictions of modern automotive internal combustion engine by itself is insoluble. Because Here, in the automotive power train set up the transmission and main reducer in order to achieve the purpose of deceleration by moment. Speed The main function of performance: ⑴ change gear ratio of motor vehicles, and expand the wheel drive torque and rotational speed of the Fan Wai, in order to adapt to constantly changing driving cycle, while the engine in the most favorable conditions within the scope of work; ⑵no change in the direction of engine rotation, under the premise of the realization of cars driving back; ⑶the realization of the free, temporary Interruption of power transmission, in order to be able to start the engine, idling, etc.. V ariable-speed drive transmission by the manipulation of institutions and agencies. Change the transmission ratio by way of transmission is divided into There are class-type, non-stage and multi-purpose three. Have class most widely used transmission. It uses gear drive, with a number of transmission ratio setting. Stepless transmission Continuously V ariable Transmission (CVT) transmission ratio of a certain The framework of multi-level changes may be unlimited, there is a common type of power and torque (dynamic fluid-type) and so on. Continuously V ariable Transmission Transmission development is the ultimate goal, because only it can make the most economical engine in working condition Can provide the best vehicle fuel economy and optimal power in order to provide the most comfortable By the feeling. Today's CVT is a typical representative of the CVT