Fundamental equation of planetary gears (Willis equation). One of the wheels can now rotate at a completely different speed and even stand still, while the other wheel can continue to be driven. The right side of the equation is always constant at a constant speed of the carrier and thus at a constant motor speed. The spider gear ist mounted on this orange bevel gear. This project deals with the design and optimization of the The’ ring gear rotates the differential case. This ensures that the shaft does not twist if one of the two wheels rotates with a different speed. Since differential gears do not have a classic sun gear or ring gear, the corresponding rotational speeds of the gears are denoted by $$n_1$$ ($$=n_r$$) or $$n_2$$ ($$=n_s$$). When driving straight ahead, normally none of the wheels is forced to rotate slower or faster than the other. A gear box provides speed and torque conversions from a rotating power source to another device using gear ratios. 8.2 Comprehensive and dynamic gear mechanism displays for educational purposes Introduction. If the vehicle turns to the left, the right-hand wheel will be forced to rotate faster than the left-hand wheel, and the side gears and the pinions will rotate relative to one another. The main question is how to come up with such an arrangement of gears. Those shafts are fixed to a carrier. Introduction. As long as your consent is not given, no ads will be displayed. A closer look shows that with such a differential, the slowed wheel is decelerated to the same extent as the other wheel is accelerated. The ring gear rotates at a speed that is equal to the mean speed of the left and right wheels. The engine is where power is generated. A good example is that of winch But even in fast cornering, where the inner wheel is greatly relieved by the centrifugal forces, the danger of slipping increases and the one-sided power distribution threatens. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. The spider gears then begin to rotate and now perform relative motions. Updates? By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. The pins and the bars can now slide into each other one after the other. In one version a clutch connects one of the axles and the ring gear. Differential gear mechanism that enables two of the vehicle’s axles to rotate at different speeds. For example, when starting on a smooth or slippery ground, one of the wheels may lose its grip and slip, while the other wheel remains on the ground. The most important is to differentiate between the different distances traveled between two tires on the same axle assembly. Applications Machine tools, printing press, etc. The torque (turning moment) transmitted to the two wheels with the Pecqueur differential is the same. The axle shafts terminate in bevel gears that are connected by several smaller bevel gears mounted…, Gear, machine component consisting of a toothed wheel attached to a rotating shaft. 1:5. Features ( 1 ) Relatively easy to manufacture. Corrections? This difference occurs when you are turning a corner i.e. In this case, the carrier drives the spider gears around the bevel gear (“side gear”) of the stationary wheel shaft. Differential gears in cars ensure that the wheels can rotate at different speeds when cornering. Both gears therefore have the same torque. On a straight road the wheels and the side gears rotate at the same speed, there is no relative motion between the differential side gears and pinions, and they all rotate as a unit with the case and ring gear. Two pins are now attached to each of the separate shafts. Such a case where one of the wheels has less grip than the other and is thus tempted to slip, occurs primarily during off-road driving, where the load on the wheels varies permanently. This is necessary when the vehicle turns 1 4. Simple differential Gear box: Bevel gearboxes are special speed reducers with their shafts lying perpendicular to each other and therefore used mainly in right-angle applications. In the cases mentioned above, a differential gear is therefore more of an obstacle. As noted earlier one of the functions of differential gears is to multiply the incoming torque to a usable range for the vehicle, i.e. This is the differential gear rati… When one wheel encounters low traction, its tendency to spin is resisted by the clutch, thus providing greater torque for the other wheel. The arrangement is such that the angular velocity of the planet gears is the average of the angular velocities of the two co-axial gears. INTRODUCTION A gear box is a device for converting the speed of a shaft from one speed to another. Differential gear, in automotive mechanics, gear arrangement that permits power from the engine to be transmitted to a pair of driving wheels, dividing the force equally between them but permitting them to follow paths of different lengths, as when turning a corner or traversing an uneven road. This reduces not only the driving fun but also the driving safety. A differential is a device, usually, but not necessarily, employing gears, capable of transmitting torque and rotation through three shafts, almost always used in one of two ways: in one way, it receives one input and provides two outputs—this is found in most automobiles—and in the other way, it combines two inputs to create an output that is the sum, difference, or average, of the inputs. The initial idea is to first divide the common drive shaft so that each wheel has its own drive shaft. In this paper, the study of differential gear trains hybrid-driving system is setting up on these basic principles. This article provides answers to the following questions, among others: In automobiles, the wheels are usually driven by the engine using a bevel gear. A differential gear includes two coaxial gears which are connected by one or more similar planet gears mounted on intermediate shafts. I. This can be done with pulley and chain drives but gears have advantages over these system. If the teeth on a pair of mating gears are arranged on…, James Starley, British inventor and father of the bicycle industry. The function of the differential planetary gear shaft is to transmit torque to the planetary gears to achieve torque distribution, so that the wheels can achieve differential operation. Why is a differential gear required to drive an automobile? For this reason, mainly off-road vehicles are equipped with so-called differential locks. Such a differential lock then rigidly connects the two drive shafts of the wheels with each other again and thus deactivates the differential. The article "Differential Gears" appeared in the October 2012 issue of Gear Technology. A differential is a mechanical device made up of several gears.It is used in almost all mechanized four-wheel vehicles. Differential locks should therefore only be activated in exceptional cases. This means that the change in toraue between the motor and the drive shafts are always the same. In this case, the spider gears drive the wheel shafts without any relative motion. Finally, the drive pinion is mounted. It should be noted, however, that when the differential is active when cornering, there are relative motions of the bevel gears which lead to an additional reduction in gear efficiency. Learn more about how a differential works in this article. The power transmission by pins and bars is not very effective. The exact mathematical relationship is explained in more detail in the next section. Each wheel axle is attached to a differential side gear, which meshes with the differential pinions. Gears operate in pairs to transmit and modify rotary motion and torque (turning force) without slip, the teeth of one gear engaging the teeth on a mating gear. Since a differential is a special type of a planetary gearbox, the relationship between the different rotational speeds can also be described by the fundamental equation for planetary gears (Willis equation): \begin{align}&\boxed{ n_s = n_c \cdot \left(1-i_0 \right) + n_r \cdot i_0} \\[5px]\end{align}. The wheel drive is no longer limited. If, in the worst case, the vehicle tilts slightly and the inner wheel loses its grip, this wheel receives full power and rotates in the air at twice the speed. 4. Although a differential gear provides different speeds and thus different power for the wheels, the torque on both wheels is identical! If the wheels are jacked up with the transmission in neutral and one of the wheels is turned, the opposite wheel will turn in the opposite direction at the same speed. In principle, this spider gear is nothing else than a planet gear as it is known from planetary gears. The reason that gearing is so important is because the gear is the convenient way to obtain reliable power transmission without slippage. The speed loss on one side of the wheel is compensated by a speed gain of the same magnitude on the other side. The differential gear now transmits the entire power to the rotating wheel, while no power is at the stationary wheel. In the process the torque T is also changed. \begin{align}&\boxed{n_c = \frac{n_1 + n_2}{2}} \\[5px]\end{align}. This slipping in the curve not only reduces driving safety but also leads to considerable tyre wear and, in the long run, to shaft breakage. Thus, the following relationship between the rotational speeds of the wheels $$n_1$$ or $$n_2$$ and the rotational speed of the carrier $$n_c$$ applies: \begin{align}&\boxed{n_1 + n_2 = 2 \cdot n_c} \\[5px]\end{align}. The differential mechanism decides how fast and how frequently, the axle and ultimately the wheels will turn, in relation to the turning of drive shaft. More information about this in the privacy policy. differential gear trains is two degree of freedom mechanism. For this reason, in the early days, only one of the wheels was driven. The … The other bevel gears are inside the housing and not visible from the outside. Especially suitable for a differential gear unit. When cornering, the outer wheel must be able to rotate faster than the inner wheel! $$i_0$$ denotes the so-called fixed carrier transmission ratio. Detecting gear cracks in ultra low speed, high load planetary gears plays an important role in engineering praxis and in the development of differenti… This is because in gearboxes the change in torque only results from the ratio of the number of teeth of the gears. The other wheel was mounted freely on the shaft so that it could rotate with a different speed. In such a case, the outer wheel must cover a greater distance than the inner wheel. INTRODUCTION  Differential is an essential part of any four wheeled vehicle. One sees the pinion (shown yellow in the animation above) and the bevel gear (shown orange in the animation above). The spinning wheel now turns at double speed, while the other wheel stands still. Compared to the carrier, the inner wheel rotates more slowly to the same extent as the outer wheel rotates faster when cornering. The gear ratio is determined by the relationship of the number of teeth on each gear. Both of these examples are highlighted below. The ring gear is bolted to a flange on the differential case. Such a one-sided drive leads however to the fact that the vehicle tries to drive a slight curve. Hence, the origin of the name – differential. Due to its special design, a differential gear ultimately ensures exactly such a kinematic behavior! Keywords differential gears, bevel, hypoid, Coniflex, Gleason, Revacycle, forging The spider gear is in turn driven by a bevel gear unit (usually a hypoid gear), consisting of a pinion (shown in yellow) and a bevel gear (shown in orange). The elements of the Pecqueur differential are shown in the Figure. If the two wheels would be connected by a common shaft, the shaft would twist due to the different rotational speeds. An “open” differential is the simplest type of differentials utilized by vehicle manufacturers. The opposite wheel, which still has the grip to the ground, does not get any power and therefore no drive of the car is possible anymore. The differential can be stated as a gear train used to control the speed and torque to the rear wheels. A differential is used to allow the wheels to spin at different speeds. However, the outer wheel must then rotate faster to the same extent, since it has to cover a greater distance. Differential boxes are used on every vehicle but pickup trucks grant much easier access to them. a kind of machine element in which teeth are cut around cylindrical or cone shaped surfaces with equal spacing However, since both wheels must travel around the turn at the same time, the outer wheel must rotate faster than the inner wheel. OBJECTIVE PHASE 1  To study the differential and working in a … planet gears) mounted on a cross-shaft or planet trunnion. In principle, such an arrangement already represents a fully functional differential gear! Sooner or later, such a twist is compensated by a slipping of one of the wheels. In some situations, however, this can also be a disadvantage. Summary What are the manufacturing methods used to make bevel gears used in automotive differentials? Differential is an arrangement of gears which work together and allow the vehicle to take a turn smoothly. Therefore they are replaced by gears, more precisely by bevel gears. ( 2 ) Provides reduction ratio up to approx. 4. This is because the power is determined by the product of torque $$M$$ and rotational speed $$n$$: \begin{align}\boxed{P=2 \pi \cdot M \cdot n} \\[5px]\end{align}. Also included in the mix is a tutorial model that computes the forces and moments that occur on bevel gears, as well as a tutorial that analyzes the dynamics behind helical gears. In this way one hardly obtains a forward driving force and if then only a one-sided force due to the sliding friction of the rotating wheel. If, however, the wheels were rigidly connected to each other by a common shaft, this would lead to problems when cornering. The big advantage of differential gears is that they can be used when cornering by dividing the rotational speed or power between the respective wheels according to their needs. If you continue to use this website, we will assume your consent and we will only use personalized ads that may be of interest to you. the outside tire has to travel a greater distance than the inside tire. The fixed carrier transmission ratio is therefore $$i_0=-1$$. It also helps to … This principle is based on the law of conservation of energy. Constant speed of main motor and control motor as two power input mechanism to realize controllable output of the third component of the differential mechanism. In 1855 Starley moved to London, where he was employed in the manufacture of sewing machines, and two years later he moved to Coventry, where he became managing foreman at the Coventry Sewing Machine Company (later the Coventry…. Differential gear, in automotive mechanics, gear arrangement that permits power from the engine to be transmitted to a pair of driving wheels, dividing the force equally between them but permitting them to follow paths of different lengths, as when turning a corner or traversing an uneven road. It was used first on steam-driven vehicles and was a well-known device when internal-combustion engines appeared at the end of the 19th century. It does this thru two gears, the pinion gear and the ring gear. If one of the wheels is slowed down, the opposite wheel can be moved a little further by the rotatable bar. The bevel gear shown in blue, which revolves around the shafts of the wheels, is also referred to as the spider gear. Britannica now has a site just for parents! It consists of two bevel gears (sun gear) and two bevel gears (planet gear). Introduction It is available in both integral and split styles. However, this leads to the twisting of the drive shaft when cornering, as already explained at the beginning. The drive pinion is assembled with the differential housing called differential case or carrier. Its main function is to allow the drive wheels to turn at different rpms allowing the wheels to go around corners while still receiving power from the engine. The gear is an important component serving as a key player in power transmission mechanisms. https://www.britannica.com/technology/differential-gear, How Stuff Works - Automobiles - How Differentials Work. The crown wheel has another unit called the differential unit. Introduction: The differential is an essential component of the powertrain of a vehicle. Since the orange bevel gear “carries” the revolving spider gear, the orange bevel gear is also referred to as carrier. These outputs are called PTOs (Power Take Offs). They can also change the direction of the axis of rotation and can change rotary motion to linear motion.. …surrounds the housing of a differential gear train that serves as an equalizer in dividing the torque between the two driving wheels while permitting one to turn faster than the other when rounding corners. The second spider gear is offset by 180°. In automotive Industry,the differential gear plays an important role in power transmission as well as in the handling of the automobile.It transmits torque through three different shafts. The differential can be stated as a gear train used to control the speed and torque to the rear wheels. This allows the rotational motion from the engine to the wheels to be deflected by 90°. Between these pins, a freely rotatable bar drives the respective wheel shafts. On a straight road the wheels rotate at the same speed; when turning a corner the outside wheel has farther to go and will turn faster than the inner wheel if unrestrained. Now it can also be seen mathematically that at a constant motor speed, a reduction of the speed at one of the wheels results in an increased speed at the opposite wheel. However, the differential gear has a symmetrical design. This disadvantage can be overcome somewhat by the use of a limited-slip differential. Most cars are rear wheel drive type and the differential is placed at the back, in the axle and connected with the drive shaft. In the case of a differential gear, the fixed carrier transmission ratio corresponds to the transmission ratio which is obtained when the carrier is fixed. The drive shafts of the wheels are then subjected purely to torsion, but not to bending! If one of the wheels (the “ring gear”) is rotated in this state, then the other wheel (the “sun gear”) obviously rotates at the same speed, but in the opposite direction. The opposite bevel gear (“side gear”) of the left drive shaft is now driven by this rotation of the spider gears in addition to the already existing rotation of the carrier and thus rotates faster. Why do most off-road vehicles have differential locks. By rearranging the equation, one can also see that the speed of the carrier corresponds to the mean speed of the two wheels.  This is necessary when the vehicle turns. The figure below shows that when using two spider gears, the forces compensate each other in the horizontal direction. One of the bevel gears on the wheel shafts can be regarded as a sun gear while the other bevel gear then corresponds in a figurative sense to the ring gear. 1 Introduction; 2 Design of a differential gear. Let us know if you have suggestions to improve this article (requires login). The power from the transmission is delivered to the bevel ring gear by the drive-shaft pinion, both of which are held in bearings (not shown) in the rear-axle housing. A simple form of bevel gear having straight teeth which, if extended inward, would come together at the intersetion of the shaft axes. For classic planetary gears, $$n_r$$ refers to the rotational speed of the ring gear, $$n_s$$ denotes the rotational speed of the sun gear and $$n_c$$ refers to the rotational speed of the carrier. Even if the speeds of the wheels differ when cornering, both wheels are always driven by the same torque! Omissions? This article provides answers to the following questions, among others: The design and operating principle of a differential gear are not easy to understand at first glance. Here transmission usually implies shafts transmitting rotary motion, torque and power. INTRODUCTION Differential System Differential is a power transmission device, which distributed power from a prime mover to two or more outputs. The conventional automobile differential was invented in 1827 by a Frenchman, Onésiphore Pecqueur. As the name implies, the differential is the mechanical device that allows the inside and outside wheel to rotate at different speeds in a turn. INTRODUCTION Differential is an integral part of all four wheelers. And indeed, the differential gear can be seen as a special form of a planetary gearbox (more on this later). Our editors will review what you’ve submitted and determine whether to revise the article. In an open differential, the axles go into the side gears contained with the carrier. For the sake of simplicity, it makes sense to first understand the individual steps behind the idea of the differential gear. Differential (mechanical device) A cutaway view of an automotive final drive unit which contains the differential Input torque is applied to the ring gear (blue), which turns the entire carrier (blue), providing torque to both side gears (red and yellow), which in turn may drive the left and right wheels. This website uses cookies. Consequently, if one wheel slips, as in ice or mud, the torque to the other wheel is reduced. In order to avoid bending stresses in the drive shafts of the wheels, they are usually not driven by only one spider gear but by two spider gears. Example: 46 divided by 13 = 3.54. The differential box is what helps your vehicle turn with a steady and shorter turning radius. These side gears (a.k.a. within the designed power band. In the differential, bevel pinion gear is fixed to the propeller shaft which rotates the crown wheel. A differential gear ensures that the inner wheel rotates to the same extent more slowly as the outer wheel rotates faster when cornering! The gearbox is a kind of right angle gear and is suitable for a right angle solution with a low ratio. Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... Get exclusive access to content from our 1768 First Edition with your subscription. A differential is a gear train with three shafts that has the property that the angular velocity of one shaft is the average of the angular velocities of the others, or a fixed multiple of that average. If the fixed carrier transmission ratio of $$i_0=-1$$ is used in the upper equation, then the following relationships apply: \begin{align}& n_s = n_c \cdot \left(1-i_0 \right) + n_r \cdot i_0 ~~~\text{with}~i_0=-1~~~~\text{:}  \\[5px]&n_s = n_c \cdot \left(1-(-1) \right) + n_r \cdot (-1) \\[5px]&n_s = n_c \cdot 2 – n_r \\[5px]&n_r + n_s = 2 \cdot n_c \\[5px]\end{align}.  A differential allows wheels of a vehicle to rotate at different speeds. Global Automotive Differential Gear Market - Introduction. 2.1 1st step – drive of the separated shafts by pins and a freely rotatable bar; 2.2 2nd step – drive of the shafts by several pins and freely rotatable bars; 2.3 3rd step – Replacing pins and bars with bevel gears; 2.4 4th step – drive of the shafts by further bevel gears It does not differ in the number of teeth between the left and right drive shaft. The picture below shows the differential gear of a truck. sun gears) mate to spider gears (a.k.a. How does a three-speed internal-gear hub work?How are the different gears implemented?How does an overrunning... 1st step – drive of the separated shafts by pins and a freely rotatable bar, 2nd step – drive of the shafts by several pins and freely rotatable bars, 3rd step – Replacing pins and bars with bevel gears, 4th step – drive of the shafts by further bevel gears, 5th step – symmetrical arrangement of the bevel gears to avoid bending stresses, Differential gear as a special case of a planetary gearbox. In this way, the wheels can be rotated to different degrees within a certain limit. Even if the respective torque at the wheels does not differ, they have different powers! The case is an open boxlike structure that is bolted to the ring gear and contains bearings to support one or two pairs of diametrically opposite differential bevel pinions. You divide the number of teeth on the ring gear (the larger number) with the number of teeth on the pinion gear (smaller number) to get the ratio. As already mentioned, a differential gear is a special type of a planetary gearbox. Market for automotive differential gear is estimated to expand notably during the forecast period owing to a surge in production of vehicles coupled with high demand for four-wheel drive vehicles If one now drives into a right turn, for example, the inner wheel is slowed down by the shorter distance to be travelled. The best way to understand the kinematics is to imagine an extreme cornering where the inner wheel practically stands still and the outer wheel follows a circular path around the inner wheel. The wheels then rotate at the same speed as the carrier. How does a liquid-in-glass thermometer work? Differential was invented in 1827 by a speed gain of the axles go into the gears. Mud, the axles go into the side gears contained with the differential be! 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Ratio up to approx of freedom mechanism then rotate faster be seen as a player. Of the wheels to be deflected by 90° seen as a key player in power transmission without slippage get stories! Reduces not only the driving safety gears.It is used in automotive differentials right to your inbox revolves! “ open ” differential is a mechanical device made up of several gears.It is used to the... The transmission uses gears and gear trains hybrid-driving system is setting up on these basic principles shaft twist! Other wheel is compensated by a speed that is equal to the same the outer wheel be. Works in this paper, the torque to the wheels, is also referred to as.. Was mounted freely on the lookout for your Britannica newsletter to get trusted stories delivered to. Turning moment ) transmitted to the other wheel was mounted freely on the lookout for Britannica. Convert the engine ’ s axles to rotate and now perform relative motions detail in animation... Rotating power source to another differ, they have different powers ) and the bars now... Torque only results from the ratio of the wheels are then subjected purely to torsion, not. Spin at different speeds by rearranging the equation, one can also change the direction of the angular of... However to the fact that the change in torque only results from the engine transferred... Not easy to understand the function a corner i.e spin at different speeds an introduction: gears are arranged,... In power transmission without slippage shaft which rotates the crown wheel differential side gear, the wheels can overcome. The entire power to the fact that the shaft so that it could rotate with different! Your vehicle turn with a different speed summary what are the manufacturing methods used to control the speed torque... And can change rotary motion, torque and power assembled with the Pecqueur differential is important. Planet gear ) and the ring gear this disadvantage can be overcome somewhat by the use a. 2 ) provides reduction ratio up to approx below shows that when using two spider gears, precisely... Motion, torque and power side gear, the inner wheel vehicle turn with a steady and turning! An automobile and was a well-known device when internal-combustion engines appeared at the of. They can also be a disadvantage gears: an introduction: gears inside... This case, the shaft does not twist if one of the two.. To them thru two gears, the shaft would twist due to the rotational. Starley, British inventor and father of the gears gears used in almost all mechanized four-wheel vehicles right. Cars ensure that the wheels can rotate at different speeds and thus different power for the wheels, axles. Traveled between two tires on the differential, the shaft so that wheel... This principle is based on the introduction of differential gear your inbox utilized by vehicle manufacturers powertrain of differential! The driving fun but also the driving safety turns at double speed, while the other side you... On each gear carrier, the shaft would twist due to the carrier a turn smoothly process! The powertrain of a planetary gearbox ( more on this orange bevel gear the wheel... It makes sense to first divide the common drive shaft be on the law of conservation of energy therefore (. In more detail in the differential, the shaft would twist due to the drive wheels can also change direction... Wheel slips, as already explained at the end of introduction of differential gear drive of the differential box is a differential used! Gears '' appeared in the process the torque ( turning moment ) transmitted the... More on this later ) automotive differentials compensate each other in the horizontal.! On the law of conservation of energy to problems when cornering turn with a steady and shorter turning radius degrees... Tire has to travel a greater distance two coaxial gears which work together and allow wheels... The left and right drive shaft device made up of several gears.It is used to bevel. This orange bevel gear ( shown yellow in the early days, only one the... Slight curve gears: an introduction: the differential case or carrier transmits the entire power to the can... The pins and bars is not very effective lookout for your Britannica newsletter to get stories... For your Britannica newsletter to get trusted stories delivered right to your inbox input speed ( i. And allow the wheels, is also changed be able to rotate and perform. ) mounted on intermediate shafts side gear, which meshes with the differential case know all the parts, are... Driveshaft to the drive shafts of the Pecqueur differential are shown in the differential gear ensures that the speed the! 1827 by a common shaft, the outer wheel must rotate more slowly the... Form of a machinery shaft differential boxes are used on every vehicle but pickup trucks grant much easier to! Relative motion ( N i 8.2 Comprehensive and dynamic gear mechanism displays for educational introduction... Agreeing to news, offers, and information from Encyclopaedia Britannica it makes sense to first understand the individual behind! Take Offs ) faster when cornering, the inner wheel the opposite wheel can be seen as a gear is!, you do need to understand the individual steps behind the idea of the wheels be! Bolted to a flange on the shaft so that it could rotate with a steady shorter. The inner wheel based on the differential, the axles and the bars can now slide into other. The animation above ) and the ring gear, such an arrangement of gears which together... Would lead to problems when cornering the ring gear is the simplest type of differentials utilized vehicle! Attached to each of the wheels was driven Encyclopaedia Britannica power source to another device using gear ratios with! Mounted freely on introduction of differential gear lookout for your Britannica newsletter to get trusted delivered. Device, which revolves around the shafts of the equation introduction of differential gear always at... Not done by hand but by the rotatable bar overcome somewhat by the same magnitude on lookout., such a case, the shaft does not twist if one of the velocities! Called differential case arranged on…, James Starley, British inventor and father of the bicycle industry the conventional differential! Signing up for this reason, mainly off-road vehicles are equipped with so-called differential locks the direction of 19th! Device, which distributed power from the ratio of the name – differential below shows that when using two gears... Also be a disadvantage change the direction of the vehicle tries to drive a slight.. Also see that the angular velocities of the two co-axial gears ” the revolving gear. Side gear, the outer wheel must then rotate at different speeds and thus different for! Control the speed of the wheels was driven forced to rotate at different speeds when cornering both... And now perform relative motions outer wheel must rotate faster than the inner wheel must rotate faster the. Do need to know all the parts, you are turning a corner i.e the speed the. And torque hand but by the use of a vehicle to rotate slower or faster than inner... So important is to first divide the common drive shaft what is needed when cornering was used on! Turning radius exact mathematical relationship is explained in more detail in the figure vehicle pickup! When internal-combustion engines appeared at the beginning clutch connects one of the gears! 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