Added: 8 months ago
From: EngineeringExplained
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  • This may sound stupid, but why not stay in the top gear when you get higher speeds and better fuel economy?

  • @bloximonkey Well, for example, if I were to be in my car going 35 mph uphill, and I was in 5th gear, I'd be turning about 1500 rpms, and would have to floor it to produce enough power to go up the hill, where as if I was in 3rd I'd be closer to 3k rpms, and could climb the hill easily. You need lower gears to accelerate up to speed, and then you can switch up to a high gear to save gas (by lowering rpm).

  • @EngineeringExplained Flooring it in a high gear at a low rpm will end up being less efficient, and put lots of strain on the engine, when a gear with a better torque advantage could be selected, use less gas, and get the job done easily.

  • 3.14 x 24" (diameter of tire) = your tire travels 75.36" per spin.

    75.36" /(divided)  by 12 (12 inches in a feet) = 6.26ft per tire spin

    1st gear is10.5 revolutions for 1 tire spin

    6000rpm /(divided) by 10.5(10.5 revolutions for one tire spin) = 571 spins per min

    571(tire spins per minute at 1st gear) x 6.26ft (one spin distance)

    571 spins per min x 6.26ft= 3574ft per min

    3574ft /(divided) 5280ft(a mile) = .67 miles per min

    .67 miles per min x 60 minutes = 40.2mph

  • I would like to watch a video about car steering, if possible please

    ....!

  • wow...i cant believe i just understood everything he said.

  • This is wonderful, I am trying to get my head around gears for my driving test, I am no good at learning bare facts, need to know the theory behind it.

  • You are very good at explaining, thanks for doing that!

    

  • Awsome videos

  • Could you do another video about how a gearbox works, physically like how a gear is selected etc.

  • @HawaiiJackJr Thanks for the idea. Check out my video on automatics vs. manuals. For manuals, I explain in detail how this process works. Automatics use a system of clutches to transfer between planetary gears, which are fairly more complicated. I will add planetary gears to the pending list of videos to make!

  • nicely explained

  • the khan academy of engineering

  • Would this apply to rotary engines? I think it would but I was just curious since the eccentric shaft of the rotary engine rotates once every three rotor rotations. Thus, the n_cycle for the engine is 3 while for the piston engines, it's 2 assuming they are all four stroke engines.

  • @jy0408 Yes, this applies to rotaries. And the shaft of the rotary rotates 3 times for every one rotation of the rotor. Regardless, this shaft will have a certain rpm, and will manipulate the wheel speed through gearing in the same manner. The "transmission" I've shown is very simplified, but its principles apply to all transmissions.

  • Another great video!

    One question, regarding the 6000 RPM redline figure, is that something you made up for your example? Is it different for each car? How is it obtained/determined?

  • @davidle24 Yes, 6000 was an arbitrary number that I picked for the redline. It will be different for every vehicle. This is the speed at which the engine will no longer be able to handle the forces and heat created, and is determined based on the strength of the components in use, the valvetrain, the size of the cylinders, and many other factors.

  • @EngineeringExplained I have got heaps of question for you but I ask those that related to your video here!

    1- Could you explain Limited Slip Differential?

    2-Also what is Final Drive?

    3-In AWD vehicles if front tyres don't have a same diameter as rear tyres how do you calculate each gear's max speed?

  • I am astonished at how clearly you explained this, thank you very much!

  • Thank you so much! Subb'd. Keep it up, please, I just started learning about cars! :)

  • @ProvokeLaughter Thanks!! If you have a specific question (or a suggestion for a video) just send me a message!

  • i love you so much, you've earned yourself a new subscriber!

  • In first gear you'll have more transmission torque, due to gearing. Yes, you have to rotate the gear more times, but it's much easier for the engine to do. Hence I used the example on a bicycle. When you're pedaling on your bike, if you put it in first gear, it's very easy to get the bike moving, you don't have to put much in, and you're rotating the wheel.

  • @EngineeringExplained Try putting it in a higher gear, and accelerating at the same rate. It's nearly impossible. Cars operate in the same manner. Another huge impact is wind resistance. When you're in forth gear, traveling at say 80 mph, you have to not only push your car with the same force that air is pushing back, but also push the car so it can keep accelerating. Air resistance is the main reason cars have top speeds.

  • @EngineeringExplained The air resistance a Bugatti Veyron experiences at 250 mph is the equivalent of you trying to drive your car through water, nearly impossible. So at those speeds it's difficult to accelerate, and you have to be in a high gear to obtain these speeds.

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