Freelander 1 So... tell me about Traction Control...

Nodge68 said:

Of course it does. A spinning wheel serves very little in the way of motive force, and none at all if the the wheel is in the air.
By locking the spinning wheel on say the front axle, then the differential sends power to the opposite wheel, which by the assumption that its not spinning, means it has some useful grip.

This process is repeated many times a second sending power back and forth across the axles, which means momentum can be maintained.

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I wouldn't have thought so. If you lock a spinning wheel, you send 100% of the torque to the other wheel whilst the locked one becomes a brake! Surely the better solution is to progressively reduce the speed of the piining one to gradually transfer increasing amounts of torque across the diff to the other one until they're both close to the same speed?

I know it has been said that the FL1 TC system can't stop a wheel and that it can only slow one down, but I'm still slightly curious about that. I think it's only more modern systems that can exert that degree of fine control over the braking. However, I don't know this for a fact.

Nodge68 said:

Don't forget that the ABS ECU or Terrain Response (TR) system on the FL2 doesn't just monitor 1 wheel at a time. The system monitors all wheel sensors simultaneously, along with pump pressure, brake line pressure, vehicle motion and angle via the yaw sensor, torque output of the engine and a many other things.

The system uses all this information to determine which wheel to apply the brakes on, and for how long and how hard.

The FL1 is pretty basic by comparison to the FL2, so isn't able to lock a non-contributing wheel, but it is able to slow the spinning wheel down to the average rotational speed of the other 3.
The FL2 is much more advanced, being able to actually lock a spinning wheel like I said, but it's not relevant in this case.

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As I mentioned, this last bit sounds odd to me. Early ABS systems would lock a wheel and when it was stopped, they'd release it again. Later, as processing power increased, they could monitor wheel speed at a much higher frequency and sense impending lockup, rather than actually waiting for it to happen. this allowed manufacturers to ditch their load compensating valves and G-valves and go for Electronic Brake Force Distribution, using the ABS instead. I'm therefore assuming that early traction control systems were similarly "clunky" but later ones had finer control over wheel speed?

I found another FL1 video on YouTube. The trouble is, you can't really see what the wheels on the opposite side are doing all the time.

In that video, it can be seen that the spinning wheel is rotating in a series of jolts. This is caused by the TC grabbing and releasing the brake over and over, several times a second. The result of which causes the opposite wheel which would be rotating at vehicle speed (it has more traction) to increase speed in a matching series of jolts. This is how the TC system works. The fastest spinning wheel on each axle is braked and slowed, so the opposite wheel will receive more torque and speed up. There are some losses in the diff, and slack in the splines, but the system still works.

ABS is complicated, even in the relatively basic FL1, but it works well enough for most needs.

I don't really know or care much about all this stuff works but when I had my FL1 two or three years ago, we had some decent snow and when the country roads around here had hard packed snow and ice, I was taking nurses from our local hospital to and fro. The freelander only had mid range road tyres but it was brilliant. It climbed very icy roads easily.

Col

Colthebrummie said:

I don't really know or care much about all this stuff works but when I had my FL1 two or three years ago, we had some decent snow and when the country roads around here had hard packed snow and ice, I was taking nurses from our local hospital to and fro. The freelander only had mid range road tyres but it was brilliant. It climbed very icy roads easily.

Col

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Not knowing how it works, doesn't make it any less useful.

Nodge68 said:

In that video, it can be seen that the spinning wheel is rotating in a series of jolts. This is caused by the TC grabbing and releasing the brake over and over, several times a second. The result of which causes the opposite wheel which would be rotating at vehicle speed (it has more traction) to increase speed in a matching series of jolts. This is how the TC system works. The fastest spinning wheel on each axle is braked and slowed, so the opposite wheel will receive more torque and speed up. There are some losses in the diff, and slack in the splines, but the system still works.

ABS is complicated, even in the relatively basic FL1, but it works well enough for most needs.

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Yes, now this is puzzling. At 30 seconds in, the right hand front wheel starts spinning. Watching it at half speed, it looks like it gets 2 full revolutions in before the VCU transmits anything at all to the right and rear wheel. The around 33 seconds, you can see the rear wheel stopping and stating (although it has been said that the FL1 system can't do that)? At 39 seconds, it is stuck, with the right hand front wheel spinning and I think I can see the left hand rear wheel spinning too). For some reason, it spends several seconds like this, with the TCS seemingly not making any effort at all to brake the two spinning wheels? What I can't make out, is whether it is slowing the two spinning wheels (which is what it is claimed the FL1 TCS does) or just letting them spin. Certainly there must be SOME drive going to the left front and/or right rear wheel - or it wouldn't ever climb the last bit (which it does at 45 seconds).

On his second go, around 2m 30 seconds, again it looks like the rear right hand wheel is stopping and starting.

We really need an FL2 on the same tyres next to it!

The brake pulse is only brief. It can apply a pulse several times a second. To be able to see what's happening you need to put a marker like a big dot on each tire and film it in slow motion.

Hippo said:

The brake pulse is only brief. It can apply a pulse several times a second. To be able to see what's happening you need to put a marker like a big dot on each tire and film it in slow motion.

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Yeh, with the frame rate of these videos its difficult to see what's going on.

GrumpyGel said:

Yeh, with the frame rate of these videos its difficult to see what's going on.

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Have you tried filming it yourself then?

Hippo said:

Have you tried filming it yourself then?

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No, but when looking at these videos you are looking at the spokes turning and at standard video frame rates is difficult to see what is occurring - for example wheels may look like they're going backwards when they're obviously not.

GrumpyGel said:

No, but when looking at these videos you are looking at the spokes turning and at standard video frame rates is difficult to see what is occurring - for example wheels may look like they're going backwards when they're obviously not.

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That's very true. I found it tricky to film even at 120 frames/sec. Hence putting white dots on my tires to see what was happening. When brake pulses are applied you see the wheel slow momentarily, but not by so much that it over powers drive to the other side for too long. When you catch it right its quite clever how it reacts and corrects spinning wheels. Youtube cuts most video's to 15 frames/sec.