Gearbox question, driving style
#121
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not engineer by any chance, i am nurse by school and graphician/designer by profession :-)
10mm could saw it self in the ground, but not to asphalt or ice. Problem is to manufacture a tire and wheel able to handle 500kg what have profile of 10mm. You would also need it to be very hard. Metal spikes hard. Otherwise you would lose the advantage of having such thin tire. That would damage roads and make lot of noise.
10mm could saw it self in the ground, but not to asphalt or ice. Problem is to manufacture a tire and wheel able to handle 500kg what have profile of 10mm. You would also need it to be very hard. Metal spikes hard. Otherwise you would lose the advantage of having such thin tire. That would damage roads and make lot of noise.
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If the weight of the vehicle was enough and the power was enough, 10mm profile tyre would easily saw into asphalt or ice?
Really, it would!
I know, speaking as a nurse....
#122
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[QUOTE=richard thomas;630755][QUOTE=sandy85;630749]
I agree nearly, but for traction you need friction?
I think that the forward resistance is created by the vehicle, not the tyre itself?
For a thinner tyre, you effectively create more weight per area due to the available contact surface over the weight of the vehicle?
thinner tire have lower forward resistance (think of how much sand/snow you have to separate by moving forward) then wide tire - less resistance, less traction you need. That is one big plus. Friction is function of weight at surface (that is basic school). So more weight on smaller surface - again better for thin tire. You need wide tire only in case where thin tire comes to limits - for example if surface is so bad that you would sink by trying to apply that huge force per surface what thin tires do and you cannot make as tall thin tire to overcome the step.
I agree nearly, but for traction you need friction?
I think that the forward resistance is created by the vehicle, not the tyre itself?
For a thinner tyre, you effectively create more weight per area due to the available contact surface over the weight of the vehicle?
#123
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The 'angle of attack'?
#124
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I don't drive my Jag in the snow-there's no point as I couldn't enjoy the power & handling without having a huge crash, as you have to consider other road users.
So if I have to drive in the snow then I use my old BMW 525tds with the tyre pressures dropped by 30%.
Driving in good weather conditions is all about driving enjoyment. Driving in snow/ice/heavy rain is all about getting to your destination & remaining alive-there's no driving satisfaction in terrible weather conditions, so the Jag stays in the driveway & the BMW is used instead.
On a wet day-even if it is warm enough for the standard tyre tread to be soft & supple-the XJR still scrabbles for traction in 1st gear at full throttle if the tyre pressures are at the higher level. Drop the pressures 10% & traction improves noticeably.
In this country the roads are already so bad that it doesn't matter about metal spikes damaging roads-and that's another reason for lower tyre pressures, to give a more comfortable ride over our terrible potholed roads
So if I have to drive in the snow then I use my old BMW 525tds with the tyre pressures dropped by 30%.
Driving in good weather conditions is all about driving enjoyment. Driving in snow/ice/heavy rain is all about getting to your destination & remaining alive-there's no driving satisfaction in terrible weather conditions, so the Jag stays in the driveway & the BMW is used instead.
On a wet day-even if it is warm enough for the standard tyre tread to be soft & supple-the XJR still scrabbles for traction in 1st gear at full throttle if the tyre pressures are at the higher level. Drop the pressures 10% & traction improves noticeably.
In this country the roads are already so bad that it doesn't matter about metal spikes damaging roads-and that's another reason for lower tyre pressures, to give a more comfortable ride over our terrible potholed roads
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#125
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[QUOTE=sandy85;630766][QUOTE=richard thomas;630755]
thinner tire have lower forward resistance (think of how much sand/snow you have to separate by moving forward) then wide tire - less resistance, less traction you need. That is one big plus. Friction is function of weight at surface (that is basic school). So more weight on smaller surface - again better for thin tire. You need wide tire only in case where thin tire comes to limits - for example if surface is so bad that you would sink by trying to apply that huge force per surface what thin tires do and you cannot make as tall thin tire to overcome the step.
I think you have it - it all depends on the friction that the surface can take? Once the friction becomes more that the surface can take then the tyre will eat into the surface?
For instance, a vehicle weighing 30 tons with 4 wheels of 10mm width on a soft ground would sink up to the axles before any forward movement is attempted?
Or also, on ice where the available friction is almost nothing - it is better to use more area of the tyre tread (skate edges) to maximise friction?
I could be wrong...
thinner tire have lower forward resistance (think of how much sand/snow you have to separate by moving forward) then wide tire - less resistance, less traction you need. That is one big plus. Friction is function of weight at surface (that is basic school). So more weight on smaller surface - again better for thin tire. You need wide tire only in case where thin tire comes to limits - for example if surface is so bad that you would sink by trying to apply that huge force per surface what thin tires do and you cannot make as tall thin tire to overcome the step.
For instance, a vehicle weighing 30 tons with 4 wheels of 10mm width on a soft ground would sink up to the axles before any forward movement is attempted?
Or also, on ice where the available friction is almost nothing - it is better to use more area of the tyre tread (skate edges) to maximise friction?
I could be wrong...
#126
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I don't drive my Jag in the snow-there's no point as I couldn't enjoy the power & handling without having a huge crash, as you have to consider other road users.
So if I have to drive in the snow then I use my old BMW 525tds with the tyre pressures dropped by 30%.
Driving in good weather conditions is all about driving enjoyment. Driving in snow/ice/heavy rain is all about getting to your destination & remaining alive-there's no driving satisfaction in terrible weather conditions, so the Jag stays in the driveway & the BMW is used instead.
On a wet day-even if it is warm enough for the standard tyre tread to be soft & supple-the XJR still scrabbles for traction in 1st gear at full throttle if the tyre pressures are at the higher level. Drop the pressures 10% & traction improves noticeably.
In this country the roads are already so bad that it doesn't matter about metal spikes damaging roads-and that's another reason for lower tyre pressures, to give a more comfortable ride over our terrible potholed roads![Smile](https://www.jaguarforums.com/forum/images/smilies/smile.gif)
So if I have to drive in the snow then I use my old BMW 525tds with the tyre pressures dropped by 30%.
Driving in good weather conditions is all about driving enjoyment. Driving in snow/ice/heavy rain is all about getting to your destination & remaining alive-there's no driving satisfaction in terrible weather conditions, so the Jag stays in the driveway & the BMW is used instead.
On a wet day-even if it is warm enough for the standard tyre tread to be soft & supple-the XJR still scrabbles for traction in 1st gear at full throttle if the tyre pressures are at the higher level. Drop the pressures 10% & traction improves noticeably.
In this country the roads are already so bad that it doesn't matter about metal spikes damaging roads-and that's another reason for lower tyre pressures, to give a more comfortable ride over our terrible potholed roads
![Smile](https://www.jaguarforums.com/forum/images/smilies/smile.gif)
(Or the Jag if I fance some fun....)
#127
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However, a tank has different priorities in life compared to a tractor or a Jaguar
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#128
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[QUOTE=sandy85;630776][QUOTE=richard thomas;630771]
partly. there have to be some math formula for it somewhere on wiki, i am sure, but in reality it is so, that you would need so huge tire to get the traction of thin tire that it is not realistic. You would have to reach the point where weight of the car does not matter anymore (think monster truck).
traction is weight to surface. nothing else. You never get better traction by using bigger surface and having same weight. But if your surface or tire breaks, you lose the traction. On ice is wide track never benefit. On snow it is benefit only if you would sink so deep that you would not come out.
Aaahh, but we are back to friction - is it untrue that Formula 1 cars were given narrower tyres to reduce the traction in order to slow down the cars and make the sport safer?
partly. there have to be some math formula for it somewhere on wiki, i am sure, but in reality it is so, that you would need so huge tire to get the traction of thin tire that it is not realistic. You would have to reach the point where weight of the car does not matter anymore (think monster truck).
traction is weight to surface. nothing else. You never get better traction by using bigger surface and having same weight. But if your surface or tire breaks, you lose the traction. On ice is wide track never benefit. On snow it is benefit only if you would sink so deep that you would not come out.
#129
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The T34 tank managed to travel a couple of thousand km's over Europe in all weather conditions, from the icy snowfields through to the muddy roads in the Russian spring thaw. It was so flexible because it had very wide tracks for it's weight & could travel over terrain thought to be impassable by other vehicles & tank designs.
However, a tank has different priorities in life compared to a tractor or a Jaguar![Smile](https://www.jaguarforums.com/forum/images/smilies/smile.gif)
However, a tank has different priorities in life compared to a tractor or a Jaguar
![Smile](https://www.jaguarforums.com/forum/images/smilies/smile.gif)
#130
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land rover traveled more then russian tank :-). Main purpose of the tank on tracks was to move lot of weight without damaging ground or streets. Grass moves up after tank passes. Same heavy truck drives same way, and you see it for years. And in real life, you can pick the way most of the time. You do not need to drive on a slope where you would slide, you just drive around.
However I do agree that Landrover has travelled more that a Russian tank :-) although it is about 20 tons lighter....and slightly better on fuel efficiency (but only slightly)
#131
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[QUOTE=richard thomas;630781][QUOTE=sandy85;630776]
This is usually first what drivers argue with on LR Course - race cars have big tires to get traction.
It is not that simple. But it is still the same. They have big tires so they can have softer compound to decrease the effect of weight and more importantly the sliding to side. You cannot bite into the asphalt if you want to put down 7 tons needed for acceleration. You reach limit of how you can bite, so only way is to go wide.
And in case of F1, the tires also play huge role as gyroscope, same as on bikes.
It is not that simple. But it is still the same. They have big tires so they can have softer compound to decrease the effect of weight and more importantly the sliding to side. You cannot bite into the asphalt if you want to put down 7 tons needed for acceleration. You reach limit of how you can bite, so only way is to go wide.
And in case of F1, the tires also play huge role as gyroscope, same as on bikes.
Last edited by sandy85; 11-30-2012 at 06:17 PM.
#132
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Sandy, please admit that you are an engineer really? If you are not, then I am going back to school to learn to be a nurse....your logic is better than mine....
F1 cars do actually weigh a lot (even though they are very light when not moving) as the downforce created by aerodynamics makes the tyres think the car is a lot heavier than it really is.
F1 cars do actually weigh a lot (even though they are very light when not moving) as the downforce created by aerodynamics makes the tyres think the car is a lot heavier than it really is.
#133
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I think that main purpose of the tank was to travel anywhere without any consideration at all for the ground or streets?
However I do agree that Landrover has travelled more that a Russian tank :-) although it is about 20 tons lighter....and slightly better on fuel efficiency (but only slightly)
However I do agree that Landrover has travelled more that a Russian tank :-) although it is about 20 tons lighter....and slightly better on fuel efficiency (but only slightly)
#134
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land rover traveled more then russian tank :-). Main purpose of the tank on tracks was to move lot of weight without damaging ground or streets. Grass moves up after tank passes. Same heavy truck drives same way, and you see it for years. And in real life, you can pick the way most of the time. You do not need to drive on a slope where you would slide, you just drive around.
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The Russian tanks were not really bothered about damaging the road surface anyway-it was a war machine designed to get from one place to the next.
Here's a thought about traction & grip...
If you have very thin tyres & very heavy vehicle on snow, then there is only a small contact point with the surface which will have a very high pressure on it. If you squash snow very hard, then it turns to ice & then you have no traction at all
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That's why the T34 had very wide tracks-the Russians know something about winter, you see
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When I was in Moscow walking in the snow, thin shoes would just sink in the snow & it was difficult to walk. When I wore wider boots, they didn't sink in the snow as much & it was much easier to walk around.
My thin shoes crushed the snow into ice & then my feet slipped on the ice-so I wore wide boots & the problem disappeared
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#135
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exactly. Tracks are not better then wheels in any case, but are friendlier to environment, more durable (shots, explosions, wear) and the disadvantages can be overcome by driving skills or throwing raw power at it (20 fuel tanks following it). But you see that even war vehicles are mostly with wheels. Tanks are only single purpose and even nowadays not really used anymore.
However they are not so capable of coping with high speeds compared to a wheeled vehicle.
#136
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I said it earlier. Tracks or heavily deflated tires are best if you would sink too deep. You came more often to scenario where 20t car would sink then to scenario where you would slide on muddy hill. So good trade off.
Normal cars drive on roads. They do not sink, so no need for trade off.
#137
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haha, you are funny. I actually am waiting until someone proves me wrong, cannot believe that i am actually right. I am car fanatic though, for a girl at least.
you are right, didnt think about the downforce, but i believe that the downforce is still small enough that car accelerates much faster then 2t car with same power. especially in lower speeds.
you are right, didnt think about the downforce, but i believe that the downforce is still small enough that car accelerates much faster then 2t car with same power. especially in lower speeds.
At high speed the downforce created by an F1 car is more that the car weighs - so in theory only an F1 car could drive upside down in a tunnel at top speed....this is theoretically only of course - but if aircraft aerodynamics are anything to go by it is true....
#138
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[QUOTE=sandy85;630813]dont know about replacing, but high speed is not really the case. If you have the power and moneys, you can build tracks able to do it. QUOTE]
As I am led to believe, tank tracks have a very short life whatever the use mainly down to the forces (weight/power) involved.
Although it is true that there are 'rubber' tracks available for minimum damage to tarmac roads.....not sure these are considered in times of conflict though...
Hasn't this thread wandered a bit though :-)
As I am led to believe, tank tracks have a very short life whatever the use mainly down to the forces (weight/power) involved.
Although it is true that there are 'rubber' tracks available for minimum damage to tarmac roads.....not sure these are considered in times of conflict though...
Hasn't this thread wandered a bit though :-)
#139
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oh they were bothered. Because fuel trucks followed them :-). What is broken have to be rebuilt.
with your shoes, you said just what i did - if you sink so deep it became an obstacle, all you can do is go bigger. You will admit that studded shoes would move you on ice better as long as you would not sink.
with your shoes, you said just what i did - if you sink so deep it became an obstacle, all you can do is go bigger. You will admit that studded shoes would move you on ice better as long as you would not sink.
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The Russian war horses didn't need much feeding either-they would simply stop in the villages & eat the straw roofs from the primitive houses.
The main reason I had problems walking in snow with thin shoes was that the pressure caused the soft snow to change state into hard ice-something that didn't happen with wide boots as they didn't put a concentrated area of very high pressure onto a very small contact patch & cause a change of material state.
#140
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Downforce is directly related to speed, an F1 car can accelerate quickly - the downforce is good for cornering - it makes the tyres use the available grip better (due to compound/width). However downforce has an effect on speed - the greater aerodynamic downforce created, the greater the drag created which limits top speed. More downforce = More drag. Drag is turbulent air which tries to suck the vehicle backwards....
At high speed the downforce created by an F1 car is more that the car weighs - so in theory only an F1 car could drive upside down in a tunnel at top speed....this is theoretically only of course - but if aircraft aerodynamics are anything to go by it is true....
At high speed the downforce created by an F1 car is more that the car weighs - so in theory only an F1 car could drive upside down in a tunnel at top speed....this is theoretically only of course - but if aircraft aerodynamics are anything to go by it is true....