The Ingenious Mechanics of Driveshafts

this episode is brought to you by brilliant for centuries the backbone of Agriculture was the hor drawn implement this clever horsepower tool for example is a horsedrawn mowing machine used for cutting hay The Cutting apparatus consists of sharp triangular teeth that form a cutting bar and a reciprocating Sith this particular variant built by Watkins and Bryson used a shaft that transmitted power from the machine's Wheels to the Gear train that drives The Cutting mechanism what made this machine particularly noteworthy could be found within its patent issued in 1861 Watkins and Bryson described the first modern conceptualization of a drive shaft early automobiles predominantly used chain drives due to their Simplicity reliability and Manufacturing efficiency the system offered design flexibility allowing for various engines and Chassis configurations and was easier to produce with the manufacturing capabil ities of the time chain drives were also efficient in power transmission and benefited from existing familiarity and experience in other Industries like bicycles and Industrial Machinery however by the end of the century the move to more enclosed and durable gear driven systems occurred addressing the limitations of chain drives such as exposure to elements and maintenance demands the 1901 autocar designed by LS S Clark of the autocar company is considered the first shaft driven automobile in the United States the autoc car featured a water- cooled shaft driven two-cylinder horizontally opposed engine and was promoted as a revolution in automotive design at the time autocar had established the general rear end layout known today with their earlier models the engine was coupled to a then novel transmission known as a sliding Gear transmission which used the combination of Gears that could be engaged or set to Freewheel along with a dog clutch to produce three ratios the output of the transmission was flexibly coupled to an assembly known as a torque tube that housed a drive shaft and a bevel gear assembly with an integrated gear differential that routed power through axle shafts to the wheels because the entire rear drive line moved independently of the engine transmission combination on the reare suspension a flexible coupling was needed to deal with both angular differences and changes in distances as the rear suspension articulated autocar used a flexible coupler known as a universal joint specifically A variation known as a pot type universal joint this configuration used a pot shaped housing that allowed it to swivel and slide as it turns though this joint Simplicity came at the cost of high friction and wear within a year a more robust drve shaft configuration would be developed for the Dutch Spiker 60 HP the world's first gas-powered four-wheel drive race car known as the car of three firsts for its additional use of the first six-cylinder engine and four-wheel braking it pioneered the use of a Cardon universal joint in combination with a slip yolk within the drive line the Cardon universal joint traces its Origins back to the work of geramo cardano an Italian mathematician physicist and philosopher in the 16th century although cardano did not invent the joint he is edited with the widespread introduction of the concept which was initially explored for applications in geometry and astronomy a Cardon universal joint consists of two yolks at right angles to each other connected by a cross-shaped intermediate Journal allowing the transfer of rotary motion between two shafts that are not in direct line with each other it allowed for the efficient transmission of power through different angles accommodating the relative movement between components in Cardon universal joints the rolling surface minimizes the surfac to surface resistance that typically occurs in pot type universal joints where the contact surfaces are primarily sliding these early joints used bronze bushings to further cut down friction and wear by the 1920s bronze bushings would be replaced by needle roller bearings that retained their own lubrication and were capable of being regularly lubricated via a grease fitting leading to a dramatic increase in durability however unlike p hot type universal joints Cardon universal joints did not provide any axial movement to accommodate for this a slip yolk mechanism is incorporated into the drive line assembly allowing it to lengthen or contract as the rear suspension moves slip yolks consists of a splined shaft that allows one part of the Drive Line Assembly to slide into another much like the Cardon joint slip yolks can also retain their own lubrication and be regularly lubricated thep the improvements Cardon universal joints brought to Drive Line Design they possess several limitations that can lead to vibrations increased friction and excessive wear Cardon joints exhibit non-uniform rotational speeds when the input and output shafts are at an angle resulting in non-constant angular velocity transmission this velocity variation introduces torsional vibrations and cyclic loading which can lead to premature failure of components additionally the sliding action at the contact points of the joint creates friction that dramatically increases with misalignment angle and operating speed leading to energy loss and potential overheating the clearance between the bearing and journals necessary for assembly and lubrication can also cause backlash and excessive wear over time compromising the joints efficiency and lifespan throughout the 1920s several design variations have been developed to overcome the limitations of Cardon universal joints one design called the ball and trunion universal joint uses a t-shaped shaft that is enclosed within the body of the joint the trunion ends are each equipped with a ball mounted on needle bearings which can move freely in grooves within the joint housing a compensating spring is used to keep the joint in a centered neutral position in this design variations in length are permitted by the longitudinal movement of the balls in the body grooves while angular displacement is allowed by outward movement of the balls on the trunk pins the entire assembly is enclosed within a dust boot to retain lubrication while keeping contaminants out of the contact surfaces ball and trunion universal joints superseded the angle misalignment capabilities of Cardon joints allowing for up to 25 degrees of movement and its integrated slip characteristics made it ideal for use in tight spaces however the torque capacity of ball and TR and universal joints as well as its vulnerability to contamination limited its application the late 1920s also saw the introduction of double Cardon shafts as a solution to the limitation of single Cardon universal joints in this configuration two universal joints are connected by an intermediate shaft with the second joint positioned in relation to the first joint to cancel out the varying angular velocity for this configuration to work effectively the driving shaft and the driven shaft must be at equal angles with respect to the intermediate shaft although they they don't necessarily have to be in the same plane and the two universal joints must be 90° out of phase with each other this intermediate shaft which is also known as a propeller Shaft or informally the drive shaft can easily integrate a slip Yol mechanism along its body for axial movement the double card and shaft drive line configuration quickly became a popular choice for rear wheeel drive vehicles due to its flexibility manufacturability ruggedness and torque in angular capacity it became a popular choice for the hodus drive one of the most popular RAR end configurations of the time it was also easy to maintain in service requiring only periodic lubrication it did however require careful alignment of components in order for the phase cancellation to work under improper alignment the rotating shafts will experience oscillating moments that tend to bend the shaft in a direction perpendicular to the plane in which they lie this causes a phenomenon known as launch shutter in RAR wheeel Drive Vehicles as well as overall vibration and premature component failure towards the end of the 1920s a new class of universal joint was introduced called the constant velocity or CV joint CV joints were developed initially to address the limitations of Cardon joints in front-wheel drive vehicles in a front-wheel drive layout the transmission contains the final drive system in a combined unit called a transaxle that directly drives the wheels in four-wheel drive and all-wheel drive drive vehicles this front drive system alternatively may be a standalone differential driven by a transfer case or a censor differential the drive axles or half shafts that transmit this power must accommodate significant suspension movement and steering angles which would cause excessive vibration and wear if traditional universal joints were used the tractor joint was one of the first constant velocity joints to be used in a production vehicle it was invented in the early 1920s by French engineer Jean Albert gregar for the front-wheel drive 1926 tractor The Joint consists of four main components two forks and two semispherical sliding pieces the male swivel has a tongue that fits into the groove of the female swivel creating a floating connection each Fork jaw engages a circular groove on the corresponding swivel and when the input and output shafts are at an angle the driving swivel accelerates and decelerates during rotation however since the tongue and GR gr joint between the swivels is a quar of a revolution out of phase with the fork jaw the speed variation of the driven swivel and output Fork counteract the speed variation of the input components this cancellation of speed fluctuations ensures that the output speed matches the input speed resulting in constant velocity rotation in effect the tractor joint behaves as two Cardon joints coupled together while the tractor joint did offer smoother power transfer its high friction sliding action and bulky floating components made it an impractical solution the first practical CV joint design was the jeppa joint and it would become one of the most popular CV joint variants used today invented by Ford engineer Alfred H jeppa in 1926 this Innovative design is based on ball bearings in which the balls furnish the only points of driving contact between the two halves of the coupling a JEA CV joint consists of a star-shaped in race several ball bearings a bearing cage an outer race or housing and a rubber boot the inner race is splined into the driving axle shaft while the outer race is a spherical housing that is an integral part of the outer driven shaft the balls and ball cage are fitted between the two races and the close spherical fit between the three main components support the driving shaft the movement of the balls is controll controlled by the ball cage positioning the balls in a plane at right angles to the two shafts when the shafts are in the same line as the joint articulates the balls are positioned to one/ half of the angular movement of the driven shaft in practice the vast majority of CV half shafts contain two CV joints to accommodate for the extreme movement experienced by the front wheels because jeppa joints offer limited axial movement but high angle articulation in a compact package they're best suited for the outboard wheel side of the half shaft while the inboard transaction side joint provides more axial movement with less angular articulation while a jeppa joint can be used on the inboard side a less costly CV joint called a tripod joint is commonly used developed by engineer Michelle rain of glaner Spicer in the 1960s tripod joints have a three-pointed yolk attached to the driven shaft with barrel-shaped roller bearing at each end these bearings fit into a cup with three matching grooves which is mounted to the transaxle the simple design allows for axial plunge movement of the shaft along with some angular movement a typical tripod joint can accommodate up to 60 mm of plunge travel and about 25° of angular articulation despite their capabilities both jeppa and tripod joints are highly vulnerable to contaminants and rely on a flexible rubber or thermoplastic Dust Boot to retain the lubricating grease within the joint and prevent contaminants from entering These Boots are prone to tearing cracking or degrading over time due to exposure to road debris Heat and the constant flexing motion of the joint once the boot fails the grease can escape leading to accelerated wear of the joints internal components because of the precise dimensions and surface finishes needed for these components to function reliably boot failure can quickly lead to costly joint failure during World War II an alternative ball bearing based CV joint was developed by Bendix known as the bendex Weiss joint the bendex wise joint used steel balls to transmit power at an angle but employed integrated yolks as part of the shafts the yolks contain long grooved races for the steel balls permitting them to move back and forth as the drive angle of the shaft changes they typically use four balls mounted between the two yolks with a fifth ball mounted in the center to lock the four outer balls in place the center ball is held in place with a pin and when the joint is assembled the steel balls form a tight fit between the inner and outer shafts this tight fit is necessary since there is no cage to hold the balls and movement is controlled by friction between the connecting parts while this design is simpler to produce it is more sensitive to manufacturing accuracy wear and contamination when compared to Je joints it is also less serviceable due to the integrated yolks in the 1960s several manufacturers such as Volvo and eMobile experimented with using CV joints on their propeller shaft assemblies to facilitate smoother more refined feeling power transfer on their higher-end rear wheeel drive vehicles and sports cars this proved to be successful in by the 1990s the inclusion of a cushioned CV joint on propeller shafts in cars became common on both CV half shafts and propeller shafts a support mechanism known as an intermediate support bearing is required when the axle length exceeds a threshold these bearing carriers reduce Drive Line Vibrations by shortening the effective length of the axle this improves stability by minimizing flexing and whipping and it also increases the lifespan of the CV joint while CV propeller shafts offer smoother power delivery they lack the ruggedness and serviceability of traditional Cardon universal joints one solution that dates back to 1916 to produce ruggedized constant velocity in a universal joint is the double Cardon joint double Cardon joints place two Cardon joints back to back in a single unit eliminating the need to correctly phase two universal joints at the ends of an intermediate shaft to maintain true constant velocity rotation double carton joints require a centering element that ensures equal angles between the driven and driving shafts while these joints are extremely rugged Compact and Excel at high articulation angles and torque loads such as those found on off-road vehicles the centering device requires additional torque to accelerate the integral components of the joint and can generate some extra vibration at higher speeds several more elaborate variants of the double Cardon joint have been devised such as the Thompson CV joint that uses a scissor positioning mechanism though their complexity and cost have prevented Ed their Mass adoption while universal joints have seen constant development throughout the 20th century the shafts they couple have seen little change until the 1980s historically drive shafts have been made from steel typically a high strength alloy such as 4340 or 1040 steel drive shafts offer excellent torque capacity torsal rigidity and durability they are also relatively inexpensive to manufacture and have a well-established production process however Steel drive shafts are heavy which can negatively impact vehicle performance fuel efficiency and overall weight distribution in 1985 the first Composite Drive Shaft was developed by the Spicer ujoint division of the Dana Corporation for the Ford Econoline van models that year GM would also introduce its first composite drive shaft on the C4 Corvette composite drive shafts are typically made from aluminum carbon fiber glass fiber Kevlar or some combination of these material materal though more expensive to manufacture composite drive shafts are significantly lighter than their steel counterparts often weighing 40 to 60% less they possess a high strength to weight ratio when compared to steel and despite their lower weight Composite Drive Shafts offer excellent strength and stiffness enabling them to handle high torque loads without adding excessive Mass to the drive line Composite Materials also have inherent damping properties that help reduce Drive Line vibration are corrosion resistant and allow for greater design flexibility enabling Engineers to optimize the drive shafts shape thickness and fiber orientation for specific applications Drive Line components and their universal joints have been crucial elements of the automotive industry for over a century and their importance remains constant even as the industry decides its future with hybrid electric and other alternative power sources though there has been attempts to eliminate Drive Lines completely by integrating Motors directly into the wheels with Hub electric motors this approach has yet to be proven viable due to Major design challenges as a result the traditional drivetrain layout relying on drive shafts is likely to remain dominant in the near future in the world of automotive technology it's often the little things that make the biggest difference and when it comes to drive shafts and universal joints there's more Innovation packed into these seemingly simple mechanisms that meet the I creating a robust and dependable power transmission system that can endure Road use for over 100,000 miles requires a meticulous understanding of design testing data modeling and Analysis a great way to Dive Right into mastering your understanding of data modeling is brilliant.org brilliant is where you discover the thrill of learning with thousands of captivating interactive lessons in math data analysis programming and AI designed to Unleash Your Potential and transform you into a confident Problem Solver brilliant is an innov ative learning platform that stands out for its use of a first principles approach that enables you to build a solid foundation of understanding each lesson is brimming with interactive problem solving exercises allowing you to actively engage with Concepts this technique has been shown to be six times 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Channel: New Mind

Views: 348,948

Keywords: Automotive drivelines, universal joints, constant velocity joints, power transmission, driveshafts, Cardan joints, Rzeppa joints, tripod joints, double Cardan joints, composite driveshafts, torque tube, bevel gear assembly, differential, pot type universal joint, slip yoke, propeller shaft, front-wheel drive, rear-wheel drive, axial movement, angular misalignment, steel alloys, glass fiber, polymer matrix, automotive history, automotive engineering, innovation, evolution

Id: Vxfay5Y9lzY

Length: 21min 28sec (1288 seconds)

Published: Sat Mar 23 2024