Comment by Someone
9 hours ago
> Ever driven a vehicle with an automatic transmission rather than a manual gearshift with a clutch? Then you almost certainly used a fluid coupling
Are you sure?
https://en.wikipedia.org/wiki/Continuously_variable_transmis...:
“The most common type of CVT uses a V-belt which runs between two variable-diameter pulleys.
[…]
A belt-driven design offers approximately 88% efficiency, which, while lower than that of a manual transmission, can be offset by enabling the engine to run at its most efficient speed regardless of the vehicle's speed.
[…]
Disadvantages of a hydrostatic CVT include:
Reduced efficiency. Gears are one of the most efficient methods of mechanical power transmission, with efficiencies as high as 90 percent in many cases. In contrast, few hydrostatic transmission systems achieve more than about 65 percent efficiency”
CVT != Automatic transmission (which is generally hydraulic)
https://en.wikipedia.org/wiki/Automatic_transmission#Hydraul...
CVT is not the same as "automatic transmission", but it is a subtype of automatic transmission, i.e. CVT is a kind of automatic transmission, but there are also other kinds of automatic transmissions, which are more frequently used.
"Automatic transmission" just means that you do not change gears manually, which is also true for CVT.
Not sure why you are making this statement.
> "A continuously variable transmission (CVT) is an automatic transmission ..."
https://en.wikipedia.org/wiki/Continuously_variable_transmis...
There are also DCTs which IIRC don't use a torque converter. But chances are pretty good that an automatic transmission car uses a torque converter.
A hydrostatic CVT is not a torque-converter transmission (which is hydrodynamic). A hydrostatic CVT is basically a hydraulic pump, control valves plus hydraulic motor. So what you would typically find on construction or forest equipment.