Straight Cut Gears vs Helical Gears in Racing Transmission

In racing transmission design, there's a trade-off between two main types of gears: straight cut gears and helical gears. The type of gear used can significantly impact the performance, efficiency, and weight of the transmission.

Because of the axial load from the helical gears. We don't want no axial loads, and straight cut gears don't produce thrust loads. Okay, let's pretend I'm the gear. There's a y-axis going from my head to my feet that's radial force. There's an x-axis going from elbow to elbow, and that's tangential force. And there's a z-axis going from my chest to my back, and that's axial force.

In a straight cut gear, I'd be super skinny. The teeth would just hit my head and mesh instantly, so there is no axial force. Basically, since they don't produce thrust loads, you don't need all the bearings and a big box of heavy crap to absorb and deal with all that axial load. So the transmission is gonna be way, way lighter.

Heavy duty transmission casings and shafts gotta be used with helical gears for the transmission to cope with all of those additional loads. Straight cut gears save heaps and heaps of weight, and that's important in racing. The straight cut transmission's generally gonna be more efficient.

So is it strength that makes straight cut gears better for racing? Not really. It's easy to build strong gears either straight or helical, so strength isn't the issue. The problem is when you start putting huge amounts of torque through helical gears, the axial loads get so high that everything else, from transmission case and shafts and the axles, they gotta contain them loads, and that adds all the weight.

Straight cut gears simplify almost everything, from the transmission case to the design of the bearings needed, and that makes things leaner. And because there's less stuff there, you get a larger powertrain that you can place in a vehicle without risking output shafts and other bearings steering themselves apart, which is actually making a larger safety factor within the transmission itself.

A negative to straight cut gears and it's why they're not in most street cars is they produce a lot of noise. You're trading weight for all that noise, and that's no problem if you're racing. Straight cut gears are also easier to assemble. They have less catastrophic results when things go wrong because of the simple structure.

They're not gonna fly out this way. They're just gonna break. Woo, now the gearbox with straight cut gears is not necessarily a dog box. Usually, they are, but they don't have to be. Dog box refers to how the gears are engaged, and straight cut refers to the type of gears themselves.

You want to learn more about that, check out the video on dog boxes, or just buy some Donut merch. That's the quickest way to learn through osmosis. Helical gears. Thanks to Honey for sponsoring this video.

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Click the link below to add Honey to your browser for free or if you'd rather type in joinhoney.com/sciencegarage.Honey. Hey guys click on this link that means you love us. We got merchandise at shop.donut.media, and we got new stuff coming out every week. Follow us on Twitter and Instagram @DonutMedia. Follow me @BidsBarto.

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In conclusion, straight cut gears and helical gears have their own set of advantages and disadvantages when it comes to racing transmission design. While straight cut gears save weight and are easier to assemble, they produce more noise and may require heavier casings and shafts for support. Helical gears, on the other hand, provide better durability and are less prone to noise but come with a higher cost and added weight.

Ultimately, the choice between straight cut gears and helical gears depends on the specific needs and requirements of the racing transmission. It's essential to weigh the pros and cons of each option carefully and consider factors like performance, efficiency, and safety before making a decision.

WEBVTTKind: captionsLanguage: en- You want the tooth?You can't handle the tooth of these gears.Friends, Romans, countrymen,lend me your gears?That's right, gang.This week, we're talking aboutmy second favorite thing to grind, gears.Gears are super old.The first ones we know ofwere on a chariot in Chinafrom maybe the 27th century BCunder mythical Chinese emperor Huangdi.But that's not to saythey're not older than that.Before they were invented,if you told somebody to get it into gear,well, they had no idea whatyou were talking about.These days, there's all kinds of gears.There's miter gears, wormdrive gears, herringbone gears,rocket peanut gears,reingears that help Santa fly,gears of war, gears forfears, craft gear lovers,Happy New Gear, NewGear's Eve, pierced gears,gear in the headlights,John Gear, power gearing,legendary Seattle SupersonicGeary Payton, and bevel gears.There's more types of gearsthan there's types of peoplein the world, left-handedand right-handed.Today, we're focusing on twovery special types of gears,straight cut gears,sometimes called spur gears,and helical gears.And I guess, we're also gonnabe tackling some tough issues,having a discussion about race.No?Alright, everybody's shakingtheir heads no and mouthingracing.Alright, we're going tobe talking about racing.Right now, you'reprobably asking yourself,what the heck are straightgears and helical gears.That's right, I knewwhat you were thinkingbecause I can read your thoughts.Now you're thinking howdid he read my thoughts.Well, it's a genetic mutation I gotbecause my mom used themicrowave when she was pregnant.Now, you're thinking thatyou should tell your dadthat you love him.Don't, he might not say it back.Helical gears are the type of gears foundin the transmission of almostall vehicles on the road,and I say, almost, becausethere's a few cars out therethat prefer straight cut gears.These are a special type ofcar that are used to raceother cars in races tosee who can go fastestwithin the confines of a race.I think those cars are calledcars that like to go fast.The teeth on a helical gear are angled,and the teeth on a straightcut go straight out.So a helical gear canabsorb contact smoothlyand spread it out.And straight cut gets it all at once.It's the difference betweenjumping in in an ice bathor getting in slowly,or ripping a band-aid off real quickor taking your time,or building up to telling your momyou're never gonna be an astronaut doctoror just blurting it out.Sorry Mom, I'm a garage scientist.So why would some carswant straight cut gearsinstead of helical?Man, if only there wassome sort of weekly showpresenting information like thatin an entertaining fashionthat people can complain about.Wait a minute, I have a CGI creationthat lives in a program just like that.So helical gears are cylindrical gearswhose teeth are not parallelto the axis of rotation.They're cut at an angleto the face of the gear.The teeth are angled andappear as a segment of a helix,so they have helical teeth.The angle between the teethand the axis of the gearsis called the helix angle,which normally rangesfrom 15 to 45 degrees.On these gears, there'stwo pressure angles,transverse plane pressure angleand normal plane pressure angle.The module and circularpitch of helical gearsare defined on the transverse plane.They're designed to distributepressure gradually alongthe whole tooth.When two teeth on ahelical gear system engage,the contact starts at one end of the toothand gradually spreads as the gears rotateuntil the two teethare in full engagement.This gradual engagementmakes helical gears operatemuch more smoothly andquietly than other gears,and that's the reason helical gearsare used in almost all car transmissions.They make enough contactto transfer power,and they're quiet.Helical gears can also bemounted on perpendicular shafts.You adjust the rotationangle by 90 degrees.They're quieter there too,and they can transmitenergy between parallelor perpendicular axes.In any running system,with a shaft and a bearing,there's usually loads in two directions,one in the directionof the axis of rotationand the other, radially.Thrust is the net forcealong the axis of rotation.Because of the helix andthe teeth of helical gears,while the gears mesh, thrustforce is developed axially.These forces push thegear toward the bearing,hence a thrust bearing has to be placedin the direction of axial force.The axial thrust bearingshave to be able to resistthe developed thrust forces,and this restricts the amount of torquethat can be applied through the gearsbefore failures occur.The axial load produced by helical gearsdiminishes the output energyfrom the transmission.They also have a slightincrease in friction,so we get to lose some power as heat.Now, let's contrast thatwith straight cut gears,but before we do, why don't you guyshit the subscribe button sothat we can keep working hardto bring you stuff like this?The name explains it all really.The actual teeth of thegears point straight outfrom the center of the gear.They go straight out.A lot of people think thatstraight cut gears are strongerthan helical gears,and that's why they're used.Well, a lot of people don't drink Mr. Pibbthink that good deeds are rewardedand think it's a good idea to get involvedin a land war in Asiaand all these people are wrong.Race transmission with straight cut gearsare usually strong,but it's not because ofthe teeth on the gears.Straight cut gears areactually slightly weakerthan a same sized helical gear.Shut up, let me finish.Helical gears have more teeth meshing,so now you got a greaterload bearing surface area.And also, difference inefficiencies are pretty negligible.Both spur and helical gearshave about 98 to 99% efficiency.Technically, on a toothversus tooth comparison,a helical gear can carry a larger loadbecause it's diagonallypositioned on the gear,assuming tooth size is equivalent.And that means it distributesthe forces applied on itmuch more efficientlycompared to a vertical tooth.So why are straight cut gearsused in race transmissions?Because of the axial loadfrom the helical gears.We don't want no axial loads,and straight cut gearsdon't produce thrust loads.Okay, let's pretend I'm the gear.There's a y-axis goingfrom my head to my feet.That's radial force.There's an x-axis goingfrom elbow to elbow,and that's tangential force.And there's a z-axis goingfrom my chest to my back,and that's axial force.In a straight cut gear,I'd be super skinny.The teeth would just hitmy head and mesh instantly,so there is no axial force.Basically, since theydon't produce thrust loads,you don't need all the bearingsand a big box of heavy crap to absorband deal with all that axial load.So the transmission isgonna be way, way lighter.Heavy duty transmission casings and shaftsgotta be used with helical gearsfor the transmission to copewith all of those additional loads.So straight cut gears saveheaps and heaps of weight,and that is important in racing.The straight cut transmission'sgenerally gonna bemore efficient.So is it strength that makesstraight cut gears betterfor racing?Not really.It's easy to build strong gearseither straight or helical,so strength isn't the issue.The problem is when you startputting huge amounts of torquethrough helical gears, theaxial loads get so highthat everything else,from transmission caseand shafts and the axles,they gotta contain them loadsand that adds all the weight.Straight cut gearssimplify almost everything,from the transmission caseto the design of the bearings neededand that makes things leaner.And because there's less stuff there,you get a larger power trainthat you can place in a vehiclewithout risking outputshafts and other bearingstearing themselves apart,which is actually makinga larger safety factorwithin the transmission itself.A negative to straight cut gearsand it's why they'renot in most street carsis they produce a lot of noise.You're trading weight for all that noise.And that's no problemo if you're racing.Straight cut gears arealso easier to assemble.They have less catastrophicresults when things go wrongbecause of the simple structure.They're not gonna fly out this way.They're just gonna break.Whoo, now, the gear boxwith straight cut gearsis not necessarily a dog box.Usually, they are, butthey don't have to be.Dog box refers to howthe gears are engaged,and straight cut refers tothe type of gears themselves.You want to learn more about that,check out the video on dog boxes,or just buy some Donut merch.That's the quickest wayto learn, through osmosis.Helical gears.Thanks to Honey for sponsoring this video.Honey is a browserextension that automaticallyscours the interwebs for coupon codesto make sure you're gettingthe best possible deal.You know how you alwaysget to the checkoutand it's like, do youhave a discount code,and you're like, uh, no.Well, say no no more.It's super easy to install.It's literally two clicks, and it's free.You know how they say you gottaspend money to make money?Well, that may be true,but you don't have tospend money to save moneybecause Honey costs you nothing.I used it when I bought new rear struts.Honey just patiently sat in the backgrounduntil I was ready to check out,and when I was, it found acode and saved me mucho moola.Searching for codesyourself is often fruitless,and it takes all kinds of math.Do I want free shipping or 20% off?Honey does all that for youto make sure you're gettingthe best deal out there.That means more money for yourdragons hatching from eggssculpture collection.And if it doesn't find a coupon code,well, that's because there isn't one,so you can shop confidently knowingyou got the best deal out there.There's no reason not to addHoney to your browser today,like now.It literally takes two clicksand costs you no money.Click the link below to addHoney to your browser for freeor if you'd rather, type injoinhoney.com/sciencegarage.Honey.Hey, you guys, click on this link.That means you love us.We got merchandise at shop.donut.media,and we got new stuffcoming out every week.Follow us on Twitter andInstagram @DonutMedia.Follow me @BidsBarto.One of my favorite shows is Miracle Whips,and it's new, check it out here.You like gears, check out thisUp to Speed on Land Cruisers.Don't tell my wife I'm responsiblefor the weird sounds in the car.