how does an engine transfer power?

[PatiencePaysOff]

I've came across something that really bothers me. I can't seem to grasp how the engine delivers power to a car. In a go kart, I believe that when a tire spins, due to friction, its rotational motion is going to go forward. Thereafter, if we weld an axle on its centre, the axle will follow the forward motion of the wheel and will "push" the pillow block bearing which will "push" the frame. However, how does that work in everyday cars? When an engine spins the drive shaft which spins the tires, does the tire push the hub/bearing assemble OR the shaft pushes the knuckles due to the forward tire motion like go karts. It sounds weird, but I'm trying to understand something out of it.

 

[chancer]

Patience pays off. But i do not have the patience to explain this concept.

Just kidding, I just lack the patience to think that hard and put it to words.

The tire does not push anything.
The drive shaft spins the Rear diff, turning the Axle, and the tire bolted to the axle is spinning pushing the car forward.

 

[Poboy kartman]

Well...actually, ...on my 1994 F-150, the rear wheels are "pushing" the mass of the vehicle , while on my 2002 Escort, the front wheels are "pulling" the car...

But both turn the same direction and work the same basic way....

Shouldn't be hard to figure: same as a wheelchair! !! Turn a wheel and the conveyance moves....Something in paticular confusing you???

As long as a wheel is powered (by any means) and attached to a vehicle (by any means) ...the vehicle HAS to move or the wheel spin in place(burnout).

On a kart the pillow blocks only job is to hold the axle in place and let it turn.

Re-reading your post : no the driveshafts sole job is to turn the gears that turn the wheels...WHATEVER...(be it springs as on nearly every car 30 years ago...) transfers that energy to the vehicle...(essentially on a rear wheel drive...it's the springs)

 

[PatiencePaysOff]

I do get the analogy at the end. But on a fwd car, the engine spins the drive shaft, then the drive shaft spins the tires. But how does the tire pull the car? On a wheelchair, when the tire spins, the tire move forward and since the centre of the wheel goes forward, it pushes the wheelchair. But how does that translate to cars? That would mean that the shaft fixed on the centre of the tire must pull something. If there were no knuckle or no wishbone, the wheel will simply fly of in front.
I hope it makes sense

 

[bob58o]

Drive shaft turns the wheels.
Friction between the tires and street convert the torque (the rotational force that rotates the wheels) to a linear force (the force that moves the vehicle forward).

On a live axle, rear wheel drive go kart...
This causes linear acceleration of the wheels, causes linear acceleration of the wheel hubs, linear acceleration of the axle, the bearings, the bearing hangers, the frame, ...., and finally the front wheels.

On any vehicle, if you see how the drive wheel(s) is(are) connected to the frame, it seems to make sense that would be the way the wheels push/pull the frame.

If you are looking for specifics, I don't know jack about cars. BUT it should be the same on any vehicle. How do the wheels connect to the frame???? Springs? Bolts? Welds?

Not sure if this helps, but I wanted to make sure my keyboard still works.
May the Force be with you.

---------- Post added at 03:11 PM ---------- Previous post was at 02:51 PM ----------

SIDE NOTE: On any physics problem writing F=ma and drawing a Free-Body Diagram with a few arrows should get you at least two points partial credit.

 

[Poboy kartman]

Let's try this one more time: In a RWD car: (FWD don't have driveshafts) the power is transferred to gears in the rear end which turn the wheels. The axles are held in the rearend with bearings, which allow the wheels to turn without turning the rear end....now...the turning wheel is pushing the rearend forward....which in turn (because its connected to the car by springs) ....moves the car!

 

[bob58o]

Let's try this one more time: In a RWD car: (FWD don't have driveshafts) the power is transferred to gears in the rear end which turn the wheels. The axles are held in the rearend with bearings, which allow the wheels to turn without turning the rear end....now...the turning wheel is pushing the rearend forward....which in turn (because its connected to the car by springs) ....moves the car!

For his specific question about FWD vehicles...
Would a more appropriate question be "How do the Front wheels on a FWD vehicle attach to the frame?"

I might even go out on a limb and say the suspension is the culprit. Springs, bolts, welds?
The wheels should be pulling the frame, not on the engine (as it seems this may be his misunderstanding here, but I'm not sure)

 

[chancer]

I will settle this

 

[PatiencePaysOff]

https://www.google.ca/url?sa=i&rct=...rC5KR3I-t5rBRKmp3tuPEpxQ&ust=1461616424690966
This is can probably help you visualize ahaha. Cars tend to get there power through the rotation of cv axles that can twist in any direction (unlike go kart axles). So if I get what you mean, since torque is converted into linear acceleration due to the wheel, the other components will do as well, but that motion can be delivered only if the wheels and the axles are fixed to a particular frame?

 

[bob58o]

https://www.google.ca/url?sa=i&rct=...rC5KR3I-t5rBRKmp3tuPEpxQ&ust=1461616424690966
This is can probably help you visualize ahaha. Cars tend to get there power through the rotation of cv axles that can twist in any direction (unlike go kart axles). So if I get what you mean, since torque is converted into linear acceleration due to the wheel, the other components will do as well, but that motion can be delivered only if the wheels and the axles are fixed to a particular frame?

Are you asking if the wheels need to be attached to make it move?
Yes the wheels and axles need to be attached to the same frame as the engine.

 

[PatiencePaysOff]

Yes. So the forward motion of the wheel and the axle pulls/push the wishbone/steering knuckles, which in turns pushes the frame? sorry for being pushy on the questionings

 

[bob58o]

The power train is held in place by the frame... the wheels push/pull the frame, not the power train.

---------- Post added at 03:53 PM ---------- Previous post was at 03:53 PM ----------

Yes. So the forward motion of the wheel and the axle pulls/push the wishbone/steering knuckles, which in turns pushes the frame? sorry for being pushy on the questionings

Yes I think you got it now.

---------- Post added at 03:55 PM ---------- Previous post was at 03:53 PM ----------

Yes. So the forward motion of the wheel and the axle pulls/push the wishbone/steering knuckles, which in turns pushes the frame? sorry for being pushy on the questionings

i'm the king of questions. lol and giving speculative answers I don't know much about. lol

all advice comes with a disclaimer.


EDIT: After looking at that pic, it seems you "Had It" the whole time.

 

[PatiencePaysOff]

I think I should stop over thinking about it before it drives me nuts

 

[machinist@large]

I think I should stop over thinking about it before it drives me nuts

Sounds like a good idea......

 

[Poboy kartman]

WAIT!!!!! But how do they go backwards????

(I'm. NOT going to Heaven! )

 

[itsid]

Well Patience...
you're trying to understand the concept of transmission from an outside observer point of reference (aka car passing by)
That is quite challenging if you do not fully understand the much simpler point of reference first
(be the car !)

So if you move the frame of reference to the car itself, the observation is very simple indeed.

linear motion of the pistons is transfered to rotation via the crankshaft, which is then passed along through the clutch to various gears (no matter if right angled as for a driveshaft or not)
to the rear wheels.
And the wheels then push the road in a specified direction.

See.. very simple for this frame of reference.
Now the outside observer has again the wheel pushing the -now fixed- road and thus the wheels push the axle, which in turn push their bearings, which in turn push their bearing retainer, which push... endless number of nuts and bolts... which then push the chassis which in turn takes all the rest of the parts with it.

But frankly you shouldn't overcomplicate things at all...
in physics all frames of reference are equally valid,
and picking the easiest one first is by far the most convenient way of doing this

And since we mainly talk about friction when it comes to moving cars(bikes/karts/trolleys...)
we can safely assume that a structurally sound force fitted connection (nuts/bolts) will hold up much longer than a non permanent friction fitted connection (tyre/road).

So yeah, why bother with that.

If you want to know if a car itself is being pushed or pulled by the wheels, then you must differentiate between RWD and FWD; since that would be determined by thecenter of mass of the vehicle in regards to the driven axle..(beware of All wheel drives a huge PITA to calculate just assume it pushes AND pulls )

If however you want to know the forces applied to a certain part of the car/kart; then
it's fairly easy again..
say the rear axle bearing..
take the easiest one (say gravity) add a second force where applicable (forward momentum)
calculate the resulting vector, add the exact same forces and add them to the outer bearing race on the opposite sides so the two cancel out.. et voila; you're done.
(see, the easiest frame of reference )

'sid

 

[bob58o]

[/COLOR]

But frankly you shouldn't overcomplicate things at all...
in physics all frames of reference are equally valid,
and picking the easiest one first is by far the most convenient way of doing this


'sid

I like the frame of reference where I ride on a photon next to a go kart. lol keeps me looking young.

 

[KartFab]

I think I should stop over thinking about it before it drives me nuts

Be patient, it pays off

 

[Mikegtrxu1]

Holly crap, my mind is blown. I am struggling to make sense of this. The basic principles between a car and a go kart are very similar. In a car, you can have independent suspension, but let's explain this simply and use a live axel rear wheel drive layout to make sense of this situation. You have the driveshaft which delivers power to a differential which basically inverts this drive to side to side. Now, I won't go into how a diff works, but it basically delivers power to whichever wheel has less resistance or traction. Anyway, power is delivered to the wheels via half shafts which go into the hubs, attached to by the wheels. The wheels move in a circular motion and this resistance between tire and ground surface is called traction. You are then pushed forward. What holds the differential, nuckles and axels to the car is a combination of arms, shock absorbers, bushings and springs. Known as suspension. Suspension delivers enough movement to produce a decent ride quality which also being stuff enough to hold the axel in place. Hope that helps. Probably doesnt, but my 2c

 

[mkIVgladiator]

the engine transfers power by gear ratio... mechanical engineering... check my build... dynamic suspension ... redesigned sprocket... welded a shaft on the clutch outer race... works well good ride and doesn't look like childs play .... 10hp snowblower motor coil spring from a SUV, works really well .. the clutch is a t40 sprock off ebay 1 inch bore cost like $90 ... go kart was $80 and motor was $50....