dieseldave:
you’ve hit exactly the right priciple, but when you get to the heavier type of artics (generally) you’ll possibly find that there are 16 gears.
(But for exactly the reason you gave.)
The 16 speed gearbox works like either of the two types at the very start of this post, but there’s an extra switch on the gearstick (called a ‘splitter’) which also has a ‘high’ and ‘low’ position. This ‘splitter’ has the effect of doubling the available number of gears in the gearbox, but you can leave the splitter switch where it is, and just use the gearstick to shift as normal. Theoretically, you’re going up/down the gearbox a ‘whole’ gear at a time.
Let’s imagine you’re carrying a fairly heavy load and pulling up a hill. If you changed up to the next gear with an 8-speed gearbox, you’d find that the gap in in the climbing capabilities of each gear to be too big, so you’d lose speed and almost stall. On the other hand, if you keep to the gear you’re using, the engine is revving uneconomically. That’s the time to use the ‘splitter.’
To use the splitter, you usually pre-select the split using the splitter switch, but nothing will happen until you next operate the clutch. After you’ve got used to doing this, it’s no different to any other gearchange.Another way to think of this is to imagine that you only need to use the gearstick for every other gearchange, because you’re going up/down the gearbox 'half 'a gear at a time.
i knew it was some where but i just couldnt remember where.
diesel dave saves the day again with his very helpful thread about different gear types
trucknetuk.com/phpBB2/viewtopic.php?t=24700
now i dont feel such a plumb asking daft questions