Enable power transmission at varied angles and varied lengths. ➢ Enable an automatic transmission have no clutch that disconnects the transmission from. The AF and AF automatic transmissions are the four-speed automatic transmission Check the automatic transmission (each clutch, brake and gear) for. of the automotive transmission market since is reflected in numerous new Variants, e.g. automatic transmissions, continuously variable transmissions.
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Automatic Transmission Basics. Automatic Transmissions/Transaxles contain. 3 Major Components or Systems. 1) Torque Converter. 2) The Planetary Gears. [PDF] Automatic Transmission System - Download as PDF File .pdf), Text File . txt) or read online. There is no clutch pedal in an automatic transmission car. • There is no gear shift in an automatic transmission car. Once you put the transmission into drive.
Published on Jan 10, Abstract The transmission is a device that is connected to the back of the engine and sends the power from the engine to the drive wheels. An automobile engine runs at its best at a certain RPM Revolutions Per Minute range and it is the transmission's job to make sure that the power is delivered to the wheels while keeping the engine within that range. It does this through various gear combinations. In first gear, the engine turns much faster in relation to the drive wheels, while in high gear the engine is loafing even though the car may be going in excess of 70 MPH. In addition to the various forward gears, a transmission also has a neutral position, which disconnects the engine from the drive wheels, and reverse, which causes the drive wheels to turn in the opposite direction allowing you to back up.
Driving a manual transmission is especially painful in stop-and-go traffic, where you constantly have to change your gear state. You might also make the case that having to concentrate on shifting your transmission takes some of your attention away from the actual driving, which is dangerous, because you might be concentrating on your tachometer or your gearshift when you really should be focusing on the traffic.
An automatic transmission bypasses these problems entirely. Planetary Gear Sets The automatic system for current automobiles uses a planetary gear set instead of the traditional manual transmission gear set.
The planetary gear set contains four parts: sun gear, planet gears, planet carrier, and ring gear see Figure 1. Based on this planetary set design, sun gear, planet carrier, and ring gear spin centrifugally. By locking one of them, the planetary set can generate three different gear ratios, including one reverse gear, without engaging and disengaging the gear set.
Normally an automatic transmission system has two planetary gear sets with different sizes of sun gears with their planet gears inter-meshed. Only one planet carrier is used to connect both sets of planet gears. This is called a compound planetary gear set.
This design can generate four different gear ratios and one reverse gear.
Hydraulic System It uses a special transmission fluid sent under pressure by an Oil Pump through the Valve Body to control the Clutches and the Bands in order to control the planetary gear sets. Dark brown or black ATF can be an indicator of a transmission problem, vehicle abuse, or fluid that has far exceeded its useful life.
Over-used ATF often has reduced lubrication properties and abrasive friction materials from clutches and brake bands suspended in it; failure to replace such fluid will accelerate transmission wear and could eventually ruin an otherwise healthy transmission.
However, color alone is not a completely reliable indication of the service life of ATF as most ATF products will darken with use.
The manufacturer's recommended service interval is a more reliable measure of ATF life. In the absence of service or repair records, fluid color is a common means of gauging ATF service life.
Continuously Variable CVT and dual-clutch transmissions often use specialized fluids. The world's first mass-produced automatic transmission, the Hydra-Matic 4-speed, was developed by General Motors GM for the model year. This transmission fluid was only available at Oldsmobile, Pontiac, and Cadillac dealerships.
Subsequent automatic transmission and fluid coupling technologies, and difficulties with fluids in cold and hot temperature extremes led to a need for longer lasting, higher quality transmission fluids. Additionally, a better system of automatic transmission fluid distribution and marketing was necessary for the long term success of the automatic transmission. In , GM released a new Type "A" fluid specification  .
In an attempt to make GM automatic transmission fluid available at retailers and service garages everywhere. From many vehicle manufacturers continued to use the next GM automatic transmission fluid specification, the Type "A" Suffix "A" fluid in their transmissions. In , Chrysler began releasing their own automatic transmission fluid specifications, see Mopar ATF for more information.
GM ATF was the same color as engine oil through Aftermarket ATF was available with red dye as an aid in fluid leak detection. In the s, s, s, and early s, ATF contained whale oil as a rust and corrosion inhibitor . To provide a fluid that would be available to the general public for service fill, oil companies and other than factory fill suppliers were allowed to develop fluids meeting the ESW M2CF specification and market these fluids under their own brand names but identified as Type F.
For purposes of whether to up or downshift. The driver pushes a shift level in simplicity, one sub-transmission is represented as a shaft All rights reserved by www. Despite the speed differentials involved, torque can be transmitted via both clutches, but the sum of the torque values from both clutches must be accounted for. For instance, if one clutch transmits the full engine torque, the 2nd partially activated clutch only generates losses as a result of its slip.
If the transmittable torque from clutch 1 is reduced the torque from clutch 2 synchronously increases, the engine will be accelerated or decelerated to the speed of the other transmission train.
Fine- tuning these procedures is easy with a fully electronic control system. Both theoretical and practical experience indicate that Fig. A disadvantage is that the clutch diameter is limited by the distance between the shafts. State-of-the-art gear design and manufacturing procedures make it possible to suppress gear noise to the same level achieved by a planetary gear transmission - in other words, these transmissions are virtually noiseless.
With or without one-way-clutches, they provide the same shift quality as planetary gear transmissions both in theory and in practice. Planetary gear transmissions were used at the time because of the power density involved and remain the standard. As was the case with the dual clutch transmission, two power-shift clutches Fig. If the torque converter has been retained as a start-up costs Include: the division of the transmission into two sub- element, the total costs for this system are comparable to the transmissions, the additional clutch, the cost of the automatic cost for planetary gear transmissions with 5 shift elements, controls for the two clutches, the operating systems for the for lay shaft transmissions with the same number of elements synchromesh elements and the hydraulic oil supply in the or for dual clutch transmissions Figure 7.
Whether this transmission is designed with a lay shaft or as a planetary gear transmission, at least each of the forward gears is Fig. All these transmissions require an oil pump for the transmission fluid supply to the torque converter and for the V.
The hydraulic control system is Figure 6 shows an example of a 4-speed automatic basically in effect an analog, partially digital hydraulic transmission like those that have been built in the USA and "computer". Even when equipped with an electronic control Japan for many years.
Figure 8 shows the total resulting efficiency rating for a 5-speed automatic transmission with a hard locked torque converter All rights reserved by www. Efficiency ratings can vary depending on represents a compromise in this direction.
However, its the design. The total drive ratio for an automatic transmission efficiency is not particularly satisfactory, and the selection of in first gear can be somewhat "longer" than for a manual shift transmission ratios is not free - it depends on the limitations transmission if a torque converter is used to assist start-up. Currently familiar higher consumption at higher velocities, e.
This means that ability to shift gears without interrupting tractive force is continuously variable transmissions make it possible to readily apparent.
This elimination of the "shift interval" achieve transmission spreads that otherwise are only possible reduces the acceleration deficit that results from the lower with five or size mechanical gears in an automatic number of transmission ratios. This wide range of transmission ratios can be used to take some of the load off the start-up element; the load exerted in this range is proportional to the square of the total transmission ratio in under drive.
It is also possible to use some of this wide range to develop an overdrive CVTs introduced in the past had relatively high losses. The high clamp loads exerted in the pulley sets required high oil pressures and large quantities of oil to facilitate the rapid adjustment of the tapered pulleys.
This means that oil pump output must be considerably higher than for a multi- step automatic. The selection of the appropriate pump design is consequently very important. The chain or belt is drawn Fig.
This can be prevented by designing speed manual transmission. There are several reasons for stiffer pulleys and shafts.
Furthermore, the full- load shift clutches - add weight to the design. It is easy to visualize how l than in a manual transmission. An optimum weigh at least 5 kg.
If the oil cooling system is added, design for a continuously variable transmission could achieve then a transmission for this vehicle performance class has loss performance in the most important partial load range a total weight of between 80 and 90 kg, depending on the similar to values for a good 4-speed automatic Figure 9.
The design volume of the torque transmitting components shift elements, planetary gear sets and shafts can be about the same as for the corresponding components of a manual transmission, but the hydraulic control system and the oil sump provide additional volume. In addition to the cost, this is the main reason why, although 5-speed manual transmissions are used in all front-wheel drive vehicles, generally only 4- speed automatic transmissions are used in these vehicles.