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.