Thread: Gearing, what's it mean?

sorry, of course it does, seniors moment. I used to have a ring pull model.

Overall gear ratio is obtained by- transmission ratio x transfer case ratio x final drive ratio. As mentioned above, this tells you how many times the engine must turn over to produce one turn of the road wheels.

Road speed is obtained thus - engine rpm x 60/ overall gear ratio x tyre revs. per kilometre.

Now you have this information you can draw a gear split chart which will give you a close approximation of vehicle performance in each gear.

mmm

Ok..

this looks pretty good for a factory 4wd..I suppose because of the big reduction in Low range the Highway cursing speed in 2WD does not suffer..

73.1:1 CRAWL RATIO with a , 4:1 LOW
RANGE RATIO

Originally Posted by goingbush

Elegant yes, but no 4WD in reverse . the freewheel isn't lockable.

...

Bit late responding to this - yes it is; that is what the ring pull on the floor does. (replaced by the yellow knob later)

John

Originally Posted by 4x4 MORE

mmm

Ok..

this looks pretty good for a factory 4wd..I suppose because of the big reduction in Low range the Highway cursing speed in 2WD does not suffer..

73.1:1 CRAWL RATIO with a , 4:1 LOW
RANGE RATIO

Guys???

In what?
It looks good as a number, but if its behind a stingy little 125cc petrol engine that needs to have the crap revved out of it to have enough mojo to keep the wheel spinning, then it isn't as useful as a big lazy diesel with less gear reduction but bucket loads more torque, assuming you are trying to do a job that requires a lot of torque at the wheel/s.

Gearing is used to adjust the available torque from the motor, to match the required torque at the wheels. Different jobs require different amounts of wheel torque-e.g. towing a heavy trailer at low speeds up a hill requires more torque than highway driving down hill unloaded-hence a taller gear is used cruising on the highway than when towing up hill.
Extrapolate from that, you can see gross vehicle mass changes the torque required, as does the environment-hills, sand, headwind, water etc.

Ahh yes Now I understand a bit more..

But that gearing was for a JK Jeep Wrangler petrol 3.6 litre with 200kw of power

But how much torque, and what shape is the torque curve?

I've heard it said that power tells you how fast you hit the wall, torque is how far you go through the wall.

Change 'wall' for 'obstacle'...