Gargo
Active Member
Good question...who when working out a gear ratio decides on a figure that best serves the car in question depending on power, weight, carrying capacity, etc
I'd say the 'etc' is quite powerful in certain markets. In the USA 1/4 mile figures sell, in the 70's Japanese motorcycles were geared for 1/4 and 1/2 mile figures. Hence they sold but didn't go round corners....
For a race circuit car, again it's the stopwatch that governs the gear ratios used.
For a motorway cruiser, I suppose mpg, max torque around cruising speed to give max acceleration for those overtakes.
Even when everything appears to be perfect, there are still imperfections. Impurities in the metal, oil, clearances etc. If the same teeth keep meshing, the worst clearance starts to wear and that wear get worse and on it goes; but only on those teeth. If you pick the gears to 'spread' the load, the wear is spread over all the gear teeth and therefore the gear set should wear slowerWhy would you need to limit the amount of times the same teeth come together
I think your asking how long before the same teeth mesh again?how do you work out when the same set will come together on a 3.08.3333333 : 1 gear set ?
Number of Turns = Lowest Common Multiple of the gears / Number of teeth on the gear your turning.
12 driving 37 : Needs the 12 turned 12 * 37 / 12 = 37 times.
For the 928 with a ratio of 12:33 Take the prime factors of 12 ( 3 and 4) and 33 (3 and 11), the 3 is shared, so:
The 12 needs turned 3x11x4 = 11 turns.
Proof, 12 turned 11 times = 132 teeth & 33 turned 4 times = 132 teeth
You can see in these calculations why a prime number is useful. As a prime number has no prime factors other than itself and 1.
They let me out when I'm good.I bet people like these don't get out much, but it is beyond clever.
“Any sufficiently advanced technology is indistinguishable from magic.”
I remember spending a day or two looking at gears at university many years ago. Fascinating field and it's no wonder there are companies that make nothing but gears and gearboxes. Remember even F1 teams buy in their gears, they too think it is just magic.
What is the MPH/1000 rpm using a LT77 in a P6. Well, you see, although I've changed the gearbox to a LT77, but also the diff to a Jag and the tyre diameter....... All I know and keep reminding my other half is the speedo reads well under the road speed.