Cavey’s weight transfer Top Tip

I nearly got to try it out today…

Arrived at my delivery at dark o’clock and went through their gate to find out that the inner gate was shut. No bother, thinks I, I’ll just back her up a bit so I’m not blocking another firms gate.

No deal. She was spinning up, and I figured it was the slush and slope. First I lifted the midlift. No chance. Jacked the air up on the unit and got enough traction to rock a little so I went to get out and drop the air from the trailer as the final part of the puzzle. Turns out there was ice under the slush and I could barely stand up without clinging onto the lorry!

So I decided I’d have a cup of coffee rather than risk my neck!

After that, I almost got to try it out again at my collection but midlift up gave enough traction to get the job done.

I was at 40t in the morning and 44t in the afternoon so had plenty of weight on my side.

Question for the experienced drivers:

Coming up the short sharp slope that was icy dirt in the afternoon, I dealt with it by knowing I normally go up it in 4th and let her lug, so I put it in manual in 3rd and took as much of a run up as I could get and held the revs at about 1300 so I’d have a bit of headroom to spin up if need be and just tried to hold the revs steady. I got up it with a few brief spins that I caught with my foot (I’d turned traction control off).

Is that a decent approach or is there a better way I could deal with a similar situation?

All sounds good to me, TC off, tag/mid lift air dumped (axle fully lifted if your lorry allows that loaded), sensible gear and the icing on the cake locked on manual, you done the lot.

Well recalled, Cavey’s instructions that is.

Which is more than can be said for me , i’m trying to get wifey’s Subaru up the driveway from standing start on the turn in the snow, car won’t have it, which is most unusual cos the sodding thing usually goes anywhere that a track layer could.
After i’d cleared some of the snow, which yes i should have done first but never needed to before, i then remembered i hadn’t turned the VSC (stability control, Subaru’s version of TC but rather more involved) off…doh , i is idiot.

slowlane:
Question for the experienced drivers:

Is that a decent approach or is there a better way I could deal with a similar situation?

You got out, so must have done it right I reckon.

Although after over 25 years, I still don’t consider my self an experienced driver.

slowlane:
I nearly got to try it out today…

Arrived at my delivery at dark o’clock and went through their gate to find out that the inner gate was shut. No bother, thinks I, I’ll just back her up a bit so I’m not blocking another firms gate.

No deal. She was spinning up, and I figured it was the slush and slope. First I lifted the midlift. No chance. Jacked the air up on the unit and got enough traction to rock a little so I went to get out and drop the air from the trailer as the final part of the puzzle. Turns out there was ice under the slush and I could barely stand up without clinging onto the lorry!

So I decided I’d have a cup of coffee rather than risk my neck!

After that, I almost got to try it out again at my collection but midlift up gave enough traction to get the job done.

I was at 40t in the morning and 44t in the afternoon so had plenty of weight on my side.

Question for the experienced drivers:

Coming up the short sharp slope that was icy dirt in the afternoon, I dealt with it by knowing I normally go up it in 4th and let her lug, so I put it in manual in 3rd and took as much of a run up as I could get and held the revs at about 1300 so I’d have a bit of headroom to spin up if need be and just tried to hold the revs steady. I got up it with a few brief spins that I caught with my foot (I’d turned traction control off).

Is that a decent approach or is there a better way I could deal with a similar situation?

What’s that in English? Got no idea what you’re talking about there? As for your question, your approach worked! Some of what you did was classic methods and some of what you did was contradicting classic methods! For a hill you did the right thing and tried to gain as much momentum as you can manage safely. Revs were too high, you came down a gear from normal when you should be looking for as high a gear as is practical to help keep the revs down and you turned traction control off when you should have left that on. However, I know from practical experience that a lead boot can do the business sometimes when you’ve used all the other advice and got nowhere! You didn’t mention dumping the air from your midlift? Oh yes you did! Sometimes it’s just putting everything together that will make that little bit of difference.

No worries mate, I accept Visa, MasterCard, PayPal and cold hard currency.

Glad to know I helped a little.

TiredAndEmotional:

slowlane:
I nearly got to try it out today…

Arrived at my delivery at dark o’clock and went through their gate to find out that the inner gate was shut. No bother, thinks I, I’ll just back her up a bit so I’m not blocking another firms gate.

No deal. She was spinning up, and I figured it was the slush and slope. First I lifted the midlift. No chance. Jacked the air up on the unit and got enough traction to rock a little so I went to get out and drop the air from the trailer as the final part of the puzzle. Turns out there was ice under the slush and I could barely stand up without clinging onto the lorry!

So I decided I’d have a cup of coffee rather than risk my neck!

After that, I almost got to try it out again at my collection but midlift up gave enough traction to get the job done.

I was at 40t in the morning and 44t in the afternoon so had plenty of weight on my side.

Question for the experienced drivers:

Coming up the short sharp slope that was icy dirt in the afternoon, I dealt with it by knowing I normally go up it in 4th and let her lug, so I put it in manual in 3rd and took as much of a run up as I could get and held the revs at about 1300 so I’d have a bit of headroom to spin up if need be and just tried to hold the revs steady. I got up it with a few brief spins that I caught with my foot (I’d turned traction control off).

Is that a decent approach or is there a better way I could deal with a similar situation?

What’s that in English? Got no idea what you’re talking about there? As for your question, your approach worked! Some of what you did was classic methods and some of what you did was contradicting classic methods! For a hill you did the right thing and tried to gain as much momentum as you can manage safely. Revs were too high, you came down a gear from normal when you should be looking for as high a gear as is practical to help keep the revs down and you turned traction control off when you should have left that on. However, I know from practical experience that a lead boot can do the business sometimes when you’ve used all the other advice and got nowhere! You didn’t mention dumping the air from your midlift? Oh yes you did! Sometimes it’s just putting everything together that will make that little bit of difference.

The reason I chose to go a gear lower I’m struggling to explain, so bear with me and I hope it makes sense!!!

I’ll invent some numbers for simplicity.

On the flat, at 50% throttle Low Gear gives you fuel for 10mph. At 25% throttle gives you fuelling for 10mph, at 50% throttle High Gear gives you fuel for 20mph.

When you go uphill you’ve got to give it more throttle (more fuel) to maintain the speed.

Let’s say you can’t approach our fictional hill faster than 10mph.

In Low Gear, you hit the hill at 10mph and your speed drops to 5mph but you can keep the throttle position at 50%. So you’re fuelling for 10mph but because of the hill you’re doing 5mph.

In High Gear, you still hit the hill at 10mph, at 25% throttle, and your speed drops to 5mph, but now you have use more throttle to maintain 5mph - you have to use 50% throttle so you’re fuelling for 20mph but because of the hill you’re doing 5mph.

If your drive tyres lose traction, all the resistance is suddenly gone so they will spin up to the “flat ground” speed that you’re fuelling for in that gear*.

In Low Gear, when you lose traction, it’ll spin up by 5mph. In High Gear it’ll spin up by 15mph. So basically what I’m saying is that because in Low Gear your actual speed is closer to the speed that you’re fuelling for, when you lose traction and the tyres spin, you’ve got less “excess” power to get rid of before you’ll get grip again. So you end up having to lift off the throttle less in Low Gear than you do in High Gear to stop the tyres spinning.

That seems to kind of make sense to me, but I’m struggling to put it into words!

• I know they will actually spin up faster than the flat ground speed because ice has less resistance than flat road but the principal stands.

I don’t know where you got that from but can I suggest you’re overthinking this?

High gear + low revs for a chosen speed reduces wheelspin.

Low gear + higher revs you will need for a chosen speed = greater risk of wheelspin. It’s that simple!

I thought in the OP that normally the hill involved was taken in 4th letting it lug, which means its a steep climb.
Last thing you want is having to change gear when conditions are bad on a climb, so going for 3rd instead locked in manual, dumping the tag/mid lift air, and locking out TC so power didn’t get cut when a wheel slipped sounded to me like as near perfect a way to make that climb as i could imagine, dumping the trailer air and lifting the tractor unit high the icing on the cake, obviously in such conditions the drive wheels are going to slip but once making that run you have to keep going.

Miles better than some of the sorry arsed efforts one sees a thousand times a day when selecting D and mashing the pedal to the floor is about the level of thought so many put into such an event.
Proof being Slowlane went up without drama, whilst the also rans would simply iron the snow down into packed ice after repeated failures to make it.

Notice you didn’t use diff lock Slowlane, from the sounds of it you were probably right.

I’ve found diff lock can be as much a hindrance as an asset, if both wheels have the same grip if wheelspin does happen then with a locked diff in an artic you’re generally going for a sideways slide when both wheels spin up, if you leave the diff unlocked then it gives one wheel a chance to spin whilst the other keeps the vehicle straight by rolling.
If you’ve got good grip with one wheel and the other is in slush/ice/mud then chances are diff lock will win the day for you.

You can only ■■■■ it and see because no two events are ever the same in my limited experience, i think in conditions like that you are going on gut judgements by what you can see and feel happening through the steering wheel and via the seat of your pants what its like under the tyres, your judgements were right SL, have a cigar mate

TiredAndEmotional:
:shock: I don’t know where you got that from but can I suggest you’re overthinking this?

High gear + low revs for a chosen speed reduces wheelspin.

Low gear + higher revs you will need for a chosen speed = greater risk of wheelspin. It’s that simple!

Juddian summed it up really - I chose 3rd because I figured I could spin, lose a bit of speed but not have to change gear when it gripped again.

Overthinking? Moi?!