|
The Gearbox
Gears are also called cogs – metal wheels
with teeth on the edges. When these are put in contact with
each other, one can turn another. The gearbox is quite
literally, a box of gears turning each other. It’s part of the
transmission, the link between the engine and the wheels. The
gears are of different sizes so that controls the relationship
between the engine speed and the speed of the road wheels.
First gear, for example, is the most
powerful gear since a small cog (from the engine) is turning a
large cog (to the wheels). This means that the engine runs
fast while the wheels turn slowly.
Fifth gear, on the other hand, has the
opposite effect. A large cog (from the engine) turns a small
cog (to the wheels). So the car travels fast while the engine
turns slowly.
This is why you need to come off the gas
during a gear change. You are slowing the gearbox down, so you
need to slow the engine down to match it.
Where you might get confused:
-
Changing gear earlier helps acceleration.
-
First gear is for 0-10mph, second for 10-20, etc.
The reality:
Higher gears allow the wheels to go
faster in relation to the engine. BUT because the engine is
turning more slowly in relation to the wheels, this means that
the engine is producing less power and the car will accelerate
more slowly.
So if you try to change to the higher
gears too early, you’ll just kill your acceleration.
First gear, of course, is the gear that
is used to get the car moving away in most cases, but has the
lowest top speed.
Top gear (usually 5th, but
some cars have 6 gears) gives the widest range of speeds, but
the slowest acceleration. In many family cars, the ranges of
speeds that are typically best for each gear are:
1st 0-15mph
2nd 5-25mph
3rd 15-40mph
4th 25mph plus
5th 40mph plus
Block Gear Changing:
You can see that there is a big overlap
between what’s available to you in each gear. This gives you
some flexibility in terms of how quickly you need to
accelerate, whether you are going up or down a hill, etc. It
also shows that it’s possible to miss out gears when you
accelerate, for example, 2nd to 4th or 3rd
to 5th. This has quite a few advantages:
-
1.
You are able to match your speed to the conditions
earlier, especially in roads with limits of 40mph and over.
-
2.
Better fuel economy because you spend less time
accelerating. Acceleration uses more fuel than going at a
constant speed because the engine has to work harder.
-
3.
You can spend less time changing gear and more time
concentrating on the road.
The only difference between a block
change and a normal gear change is that you need to leave the
gas pedal alone and the clutch down slightly longer because
the gearbox will turn much more slowly when it's in the higher
gear.
Changing Down:
The best way to change to a lower gear is to separate the
braking from the gear change & choose the right
gear for your speed after you finish braking. That way,
you spend less time coasting and more time allowing the engine
to help the car slow down. The trick to this is to keep your
distance from the vehicle in front so that you have more time
to read the speedometer and decide which gear you really need.
Remember...
Match your speed
to the situation.
Match your gear to the speed!
|
