As far as I know, all automatics have a fluid coupling (torque=20
converter) which absorbs some of the jerk when clutch(s) are engaging.=20
The clutches are either engaged or disengaged, except for the brief=20
period of changing. There is no continuous slipping mode. The fluid=20
coupling, though rare, there have been some that are not torque=20
converters, action can be likened to stirring paint with a paddle. It=20
takes energy and does generate heat, but the paddle, can, and paint are=20
not damaged. Today most torque converters have a lock-up feature, to=20
make the input and output one solid piece via a clutch built into the=20
torque converter, which results in better gas mileage.

No one as brought up CV (Continuously variable) transmission. This is=20
basically a very wide V-belt running on tapered pulleys. The distance=20
between the tapered sides of the pulleys can be adjusted, varying the=20
riding height of the belt, and the in/output shaft speed ratio. These=20
have been used for years in industrial applications where they are=20
generally driven by an electric motor which can be turned off,=20
eliminating the need for a clutch. In a car, I would think there is a=20
clutch other than widening the pulley to cause the belt to lose friction=20
to the pulley sides. Maybe can tell use how that happens.
> I was wondering if the clutch-based automatics also did this maneuver
> (i.e., slip the clutch) and if so, how do they deal with the abusive
> situation where someone tries to hold the car on a hill continuously.
> In a torque-converter type transmission, I think that this is
> relatively harmless so that some people may have gotten into it as a
> bad habit and never noticed problems. Such a person might have a lot
> of problems if he switched to a clutch-type automatic and wasn't aware
> of the difference, unless these transmissions had some way to protect
> their clutches.
>
> Sean
>
--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.