My dear chap/girl, a standard car clutch either transmits power or it
doesn't. It converts nothing. It slips only momentarily for smooth
modulation. It is designed to be either 'on' or 'off'. It is a method of
breaking the transmission of power just like a light switch. It is not like
a transformer. You just don't get it. Frankly you should read those links I
kindly provided you and stop making such a damned fool of yourself, albeit
You don't appear to understand what a clutch is used for when in
*operation*. Its function is to provide a *smooth* conversion of
torque from minimum to maximum, hence to convert torque(smoothly).
It is not at all lilke a switch, that it its whole point, to avoid the
abruptness of a switch which would stall and/or damage the
It is a switch and the smoothness of modulation is irrelevant. There are
many types of clutches but a car clutch is very similar to an aircon
compressor clutch. It is a simple switch, with some refinements. You think
otherwise. Quite simply you are wrong. A car clutch is not designed to be
slipped other than a minimum for smooth full engagement and the refinement
is to facilitate this and cushion shock loads.
Of course there are clutches that have no facility for smooth modulation. An
example of these is a dog clutch which has fierce teeth which engage. It is
nevertheless a clutch.
A torque converter is as described and is designed to slip almost constantly
and facilitates a very high first gear in the case of a motor vehicle so
that the power input can be a converted to a greater torque output at lower
revs. It is NOT a clutch. In fact it is common industrial practice to fit a
converter in conjunction with a dry clutch. In this case the clutch can be
fully engaged at low revs while the vehicle pulls away simply by increasing
the revs. The conventional clutch is nevertheless used to facilitate the
changing of the conventional synchromesh gearbox while on the move.
Also common on modern cars is the fitment of a clutch to the torque
converter to lock both halves together. In the torque converter itself there
is no mechanical link between the drive and driven sides. The drive is
purely through the fluid which is thrown from one side to the other.
Read the articles to which I provided a link!
The point is they both act as and are used at clutches the only
difference is one is manual and the other automatic.
A clutch and a convertor is like wearing a belt and braces!
A car clutch disengages drive. Its primary function is NOT to
slip unless it is a different type such as a torque limiting device which
suddenly disengages upon overload [a torque limiting clutch used instead of
say a shear bolt, but not generally fitted to cars].
A torque converter has no facility to disengage drive fully and is designed
primarily to variably slip and increase torque. Neither does it have the
lock up fully to provide a direct mechanical drive without an additional
clutch to facilitate
this. The clutch can only transmit the torque that is input. These are
In an automatic transmission clutches are used to engage and disengage the
gears. They are either engaged or disengaged apart from a short slip period
as they are modulated for smoothness and convenience. The slip causes heat
and wear which are undesirable so in some cases the modulation from release
to drive is quite sharp with shock loads being taken by the slipping torque
converter between engine and transmission
Fundamentally and contrary to your initial claim, a conventional car clutch
is not designed to convert torque. It just transmits torque or not.
Clutching is actually a means to disengage drive, not a means to multiply
torque or vary gearing ratio. Give up and stop digging.
Yes as I have reached sufficient depth to final bury your arguement
there is no need to dig futher!! (see below!!).
"the sprag is a one-way mechanical *clutch* mounted on races and fits inside
the stator" (pump, turbine, stator and cover are the four components of
a torque convertor).
I rest my case M'Lud.
Better luck next time :O)
Actually it says that the stator contains a one way clutch, a sprag in fact.
All cars have a number of clutches. This does not mean that the car is a big
clutch any more than it means that just because a converter contains a
clutch or two, that it is actually a clutch in itself.
For Dave, the first sentence defining a converter describes it as a fluid
coupling device that also acts as a torque multiplier during initial
Never any mention of a converter being a clutch, which of course it is not
and if a converter allied to a conventional synchromesh gearbox there must
be an actual clutch in the driveline to allow disconnection during a
gearchange. While synchro boxes in conjunction with torque convertors are
not common in cars they are not uncommon per-se. In an automatic or
power-shift gearbox, there is of course no need to disconnect drive to
achieve a ratio change because the clutch is integral to the gearbox in that
it replaces a synchro unit in effect, whether in a constant mesh or
planetary unit. From this it should be obvious that it does not matter which
side of the converter a clutch is fitted, either on the input shaft or the
Please do try again your widescreenness :-)
Not a good analogy. Better to consider it as a variable resistor that
allows the light to be fully on or off and anywhere inbetween.
A clutch which is only 'on' or 'off' is called a dog clutch and you find
them in most motor cycle gearboxes - as opposed to the more normal
synchromesh clutches in cars.
*7up is good for you, signed snow white*
Dave Plowman firstname.lastname@example.org London SW
That is not correct because it is not designed to be operated anywhere
in-between except momentarily as it is modulated. Try driving and regulating
your speed by slipping the clutch and see how long it lasts.
I have mentioned dogs elsewhere. The only practical operating difference
between a dog and a conventional traction automobile clutch is in the
smoothness of engagement. Both are designed to operate either engaged or
disengaged. Neither multiplies torque or alters gearing in operation.
But that is just what it is. There are a multitude of drive clutch types
designed for all kinds of jobs but when it comes down to it they have two
working modes, on and off. Any intermediate mode or delay in transition from
on to off or visa versa is purely a refinement to the fundamental operation
of the switch in the same way as most dry driven plates also have springs to
dampen shock loads which result from sudden near-slip-free engagement.
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.