LOCKING AND TOR SEN

Locking and Tor sen

The locking differential is useful for serious off-road vehicles. This type of differential has the same parts as an open differential, but adds an electric, pneumatic or hydraulic mechanism to lock the two output pinions together.

This mechanism is usually activated manually by switch, and when activated, both wheels will spin at the same speed. If one wheel ends up off the ground, the other wheel won't know or care. Both wheels will continue to spin at the same speed as if nothing had changed.

The Tor sen differential* is a purely mechanical device; it has no electronics, clutches or viscous fluids.

The Tor sen (from Torque Sensing) works as an open differential when the amount of torque going to each wheel is equal. As soon as one wheel starts to lose traction, the difference in torque causes the gears in the Tor sen differential to bind together. The design of the gears in the differential determines the torque bias ratio. For instance, if a particular Tor sen differential is designed with a 5:1 bias ratio, it is capable of applying up to five times more torque to the wheel that has good traction.

These devices are often used in high-performance all-wheel-drive vehicles. Like the viscous coupling, they are often used to transfer power between the front and rear wheels. In this application, the Tor sen is superior to the viscous coupling because it transfers torque to the stable wheels before the actual slipping occurs.

However, if one set of wheels loses traction completely, the Tor sen differential will be unable to supply any torque to the other set of wheels. The bias ratio determines how much torque can be transferred, and five times zero is zero.

VISCOUS COUPLING

Viscous Coupling

The viscous coupling has two sets of plates inside a sealed housing that is filled with a thick fluid, as shown in below. One set of plates is connected to each output shaft. Under normal conditions, both sets of plates and the viscous fluid spin at the same speed. When one set of wheels tries to spin faster, perhaps because it is slipping, the set of plates corresponding to those wheels spins faster than the other. The viscous fluid, stuck between the plates, tries to catch up with the faster disks, dragging the slower disks along. This transfers more torque to the slower moving wheels -- the wheels that are not slipping.

FINAL DRIVE CLUTCH-TYPE LIMITED SLIP DIFFERENTIAL

Clutch-type Limited Slip Differential

The clutch-type LSD is probably the most common version of the limited slip differential

This type of LSD has all of the same components as an open differential, but it adds a spring pack and a set of clutches. Some of these have a cone clutch that is just like the synchronizers in a manual Transmission

DIFFERENTIAL AND TRACTION

Differentials and Traction

The open differential always applies the same amount of torque to each wheel. There are two factors that determine how much torque can be applied to the wheels: equipment and traction. In dry conditions, when there is plenty of traction, the amount of torque applied to the wheels is limited by the engine and gearing; in a low traction situation, such as when driving on ice, the amount of torque is limited to the greatest amount that will not cause a wheel to slip under those conditions. So, even though a car may be able to produce more torque, there needs to be enough traction to transmit that torque to the ground. If you give the car more gas after the wheels start to slip, the wheels will just spin faster.

FUNGUA DIFFERENTIAL ( OPEN DIFFERENTIAL )

Open Differentials

We will start with the simplest type of differential, called an open differential. First we'll need to explore some terminology: The image below labels the components of an open differential.

When a car is driving straight down the road, both drive wheels are spinning at the same speed. The input pinion is turning the ring gear and cage, and none of the pinions within the cage are rotating -- both side gears are effectively locked to the cage.

Note that the input pinion is a smaller gear than the ring gear; this is the last gear reduction in the car. You may have heard terms like rear axle ratio or final drive ratio. These refer to the gear ratio in the differential. If the final drive ratio is 4.10, then the ring gear has 4.10 times as many teeth as the input pinion gear. 

DIFFERENTIAL NI NINI? ( WHAT IS A DIFFERENTIAL? )

What is a Differential?

The differential is a device that splits the engine torque two ways, allowing each output to spin at a different speed.

The differential is found on all modern cars and trucks, and also in many all-wheel-drive (full-time four-wheel-drive) vehicles. These all-wheel-drive vehicles need a differential between each set of drive wheels, and they need one between the front and the back wheels as well, because the front wheels travel a different distance through a turn than the rear wheels.

Part-time four-wheel-drive systems don't have a differential between the front and rear wheels; instead, they are locked together so that the front and rear wheels have to turn at the same average speed. This is why these vehicles are hard to turn on concrete when the four-wheel-drive system is engaged.

JINSI DIFFERENTIAL INAVYOFANYA KAZI (HOW DIFFERENTIALS WORKS )

How Differentials Work

                Differential-ch

If you've read How Car Engine Works, you understand how a car's power is generated; and if you've read How Manual Transmission Works, you understand where the power goes next. This article will explain differentials -- where the power, in most cars, makes its last stop before spinning the wheels.

AINA ZA KRACHI ( TYPES OF CLUTCHES )

Types of Clutches

There are many other types of clutches in your car and in your garage.

An automatic transmission contains several clutches. These clutches engage and disengage various sets of planetary gears. Each clutch is put into motion using pressurized hydraulic fluid. When the pressure drops, springs cause the clutch to release. Evenly spaced ridges, called splines, line the inside and outside of the clutch to lock into the gears and the clutch housing. You can read more about these clutches in How Automatic Transmission Works.

TUANGALIE KWA KAWAIDA MATATIZO YA CLUTCH.( COMMON PROBLEMS

Common Problems

From the 1950s to the 1970s, you could count on getting between 50,000 and 70,000 miles from your car clutch. Clutches car's can now last for more than 80,000 miles if you use them gently and maintain them well. If not cared for, clutches can start to break down at 35,000 miles. Trucks that are consistently overloaded or that frequently tow heavy loads can also have problems with relatively new clutches.

FLY WHEELS, CLUTCH PLATES AND FRICTION ( MSUGUANO )

Fly Wheels, Clutch Plates and Friction

In a Car's clutch, a flywheel connects to the engine, and a clutch plate connects to the transmission. You can see what this looks like in the video clip below.

TUANGALIE UFANYAJI KAZI WA KRATCHI ( HOW CLUTCHES WORKS )

How Clutches Work

        Diagram of car showing clutch location

If you drive a manual transmission car, you may be surprised to find out that it has more than one clutch. And it turns out that folks with automatic cars have clutches, too. In fact, there are clutches in many things you probably see or use every day: Many cordless drills have a clutch, chain saw have a centrifugal clutch and even some  have a clutch.

TUANGALIE PLANETARY GEAR SET

The Planetary Gear set

     From left to right: the ring gear, planet carrier, and two sun gears

When you take apart and look inside an automatic transmission, you find a huge assortment of parts in a fairly small space. Among other things, you see:

·         An ingenious planetary gear set

·         A set of bands to lock parts of a gear set

·         A set of three wet-plate clutches to lock other parts of the gear set

·         An incredibly odd hydraulic system that controls the clutches and bands

·         A large gear pump to move transmission fluid around

The center of attention is the planetary gear set. About the size of a cantaloupe, this one part creates all of the different gear ratios that the transmission can produce. Everything else in the transmission is there to help the planetary gear set do its thing. An automatic transmission contains two complete planetary gear sets folded together into one component. See How gear ratio works for an introduction to planetary gear sets.

Any planetary gear set has three main components:

·         The sun gear

·         The planet gears and the planet gears' carrier

·         The ring gear

Each of these three components can be the input, the output or can be held stationary. Choosing which piece plays which role determines the gear ratio for the gear set.

Planetary Gear set Ratios

One of the planetary gear sets from our transmission has a ring gear with 72 teeth and a sun gear with 30 teeth. We can get lots of different gear ratios out of this gear set.

	Input	Output	Stationary	Calculation	Gear Ratio
A	Sun (S)	Planet Carrier (C)	Ring (R)	1 + R/S	3.4:1
B	Planet Carrier (C)	Ring (R)	Sun (S)	1 / (1 + S/R)	0.71:1
C	Sun (S)	Ring (R)	Planet Carrier (C)	-R/S	-2.4:1

Also, locking any two of the three components together will lock up the whole device at a 1:1 gear reduction. Notice that the first gear ratio listed above is a reduction -- the output speed is slower than the input speed. The second is an overdrive -- the output speed is faster than the input speed. The last is a reduction again, but the output direction is reversed. There are several other ratios that can be gotten out of this planetary gear set, but these are the ones that are relevant to our automatic transmission. You can try these out in the animation below:

Animation of the different gear ratios related to automatic transmissions.

So this one set of gears can produce all of these different gear ratios without having to engage or disengage any other gears. With two of these gear sets in a row, we can get the four forward gears and one reverse gear our transmission needs. 

TUANGALIE AINA YA PILI YA GEAR BOX ( AUTOMATIC GEAR BOX ) UTANGULIZI

The 6L50 transmission is a Hydra-Matic six-speed rear and all-wheel drive automatic transmission.

If you have ever driven a car with an automatic transmission, then you know that there are two big differences between an automatic transmission and a manual Transmission:

·         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, everything else is automatic.

Both the automatic transmission (plus its torque converter) and a manual transmission with its clutch) accomplish exactly the same thing, but they do it in totally different ways. It turns out that the way an automatic transmission does it is absolutely amazing!

In this article, we'll work our way through an automatic transmission. We'll start with the key to the whole system: planetary gear sets. Then we'll see how the transmission is put together, learn how the controls work and discuss some of the intricacies involved in controlling a transmission.

TUANGALIE UHALISIA WA MANUAL TRANSMISSION GEAR BOX(A REAR TRANSMISSION )

A Real Transmission

The five-speed manual transmission is fairly standard on cars today. Internally, it looks something like this:

There are three forks controlled by three rods that are engaged by the shift lever. Looking at the shift rods from the top, they look like this in reverse, first and second gear:

Keep in mind that the shift lever has a rotation point in the middle. When you push the knob forward to engage first gear, you are actually pulling the rod and fork for first gear back.

You can see that as you move the shifter left and right you are engaging different forks (and therefore different collars). Moving the knob forward and backward moves the collar to engage one of the gears.

Reverse gear is handled by a small idler gear (purple). At all times, the blue reverse gear in this diagram is turning in a direction opposite to all of the other blue gears. Therefore, it would be impossible to throw the transmission into reverse while the car is moving forward -- the dog teeth would never engage. However, they will make a lot of noise!

Synchronizers
Manual transmissions in modern passenger cars use synchronizers to eliminate the need for double-clutching. A synchro's purpose is to allow the collar and the gear to make frictional contact before the dog teeth make contact. This lets the collar and the gear synchronize their speeds before the teeth need to engage, like this:

The cone on the blue gear fits into the cone-shaped area in the collar, and friction between the cone and the collar synchronize the collar and the gear. The outer portion of the collar then slides so that the dog teeth can engage the gear.

TUANGALIE KWA URAHISI MANUAL GEAR BOX.( A VERY SIMPLE TRANSMISSION WITH FIRST GEAR)

A Very Simple Transmission

To understand the basic idea behind a standard transmission, the diagram below shows a very simple two-speed transmission in neutral:

Let's look at each of the parts in this diagram to understand how they fit together:

·         The green shaft comes from the engine through the clutch. The green shaft and green gear are connected as a single unit. (The clutch is a device that lets you connect and disconnect the engine and the transmission. When you push in the clutch pedal, the engine and the transmission are disconnected so the engine can run even if the car is standing still. When you release the clutch pedal, the engine and the green shaft are directly connected to one another. The green shaft and gear turn at the same rpm as the engine.)

·         The red shaft and gears are called the lay shaft. These are also connected as a single piece, so all of the gears on the lay shaft and the lay shaft itself spin as one unit. The green shaft and the red shaft are directly connected through their meshed gears so that if the green shaft is spinning, so is the red shaft. In this way, the lay shaft receives its power directly from the engine whenever the clutch is engaged.

·         The yellow shaft is a splined shaft that connects directly to the drive shaft through the differential to the drive wheels of the car. If the wheels are spinning, the yellow shaft is spinning.

·         The blue gears ride on bearings, so they spin on the yellow shaft. If the engine is off but the car is coasting, the yellow shaft can turn inside the blue gears while the blue gears and the lay shaft are motionless.

·         The purpose of the collar is to connect one of the two blue gears to the yellow drive shaft. The collar is connected, through the splines, directly to the yellow shaft and spins with the yellow shaft. However, the collar can slide left or right along the yellow shaft to engage either of the blue gears. Teeth on the collar, called dog teeth, fit into holes on the sides of the blue gears to engage them.

Now, let's see what happens when you shift into first gear.

TUENDELEE KUANGALIA ZAIDI MFUMO HUU WA MANUAL GEAR BOX

Continuously Variable Transmissions

A CVT has a nearly infinite range of gear ratios. In the past, CVTs could not compete with four-speed and five-speed transmissions in terms of cost, size and reliability, so you didn't see them in production automobiles. These days, improvements in design have made CVTs more common. The Toyota Plus is a hybrid car that uses a CVT.

The transmission is connected to the engine through the clutch. The input shaft of the transmission therefore turns at the same rpm as the engine.

Six-speed manual transmission, graphic illustration.

Gear Ratio RPM at Transmission Output Shaft with Engine at 3,000 rpm 1st 2.315:1 1,295 2nd 1.568:1 1,913 3rd 1.195:1 2,510 4th 1.000:1 3,000 5th 0.915:1 3,278

A five-speed transmission applies one of five different gear ratios to the input shaft to produce a different rpm value at the output shaft. Here are some typical gear ratios:

You can read How CVTs Work for even more information on how continuously variable transmissions work. Now let's look at a simple transmission.

GEAR BOX ( TRANSMISSION SYSTEM )

KUNA AINA MBILI ZA GEAR BOXES.

1: MANUAL GEAR BOX.
2: AUTOMATIC GEAR BOX.

LEO TUANGALIE AINA HII YA KWANZA YAANI ( MANUAL GEAR BOX ).

Manual transmission gear box.

If you drive a stick-shift car, then you may have several questions floating in your head.

How does the funny "H" pattern that I am moving this shift knob through have any relation to the gears inside the transmission? What is moving inside the transmission when I move the shifter? 
When I mess up and hear that horrible grinding sound, what is actually grinding? What would happen if I were to accidentally shift into reverse while I am speeding down the freeway? Would the entire transmission explode?

In this article, we'll answer all of these questions and more as we explore the interior of a manual transmission.

Cars need transmissions because of the physics of the gasoline engine. First, any engine has a red line -- a maximum rpm value above which the engine cannot go without exploding. Second, if you have read How Horse power Work, then you know that engines have narrow rpm ranges where horsepower and torque are at their maximum. For example, an engine might produce its maximum horsepower at 5,500 rpm. The transmission allows the gear ratio between the engine and the drive wheels to change as the car speeds up and slows down. You shift gears so the engine can stay below the red line and near the rpm band of its best performance.

Ideally, the transmission would be so flexible in its ratios that the engine could always run at its single, best-performance rpm value. That is the idea behind the continuously variable transmission (CVT)

Manual transmission gear box