How does a keyless drill chuck achieve the same locking torque as a keyed chuck?

[abdulbadii]

TL;DR

How is the keyless drill chuck can have locking torque great enough

How is the working principle of keyless drill chuck, the inventor confidently estimated that it'd have locking torque great enough as the same as to the keyed one just by turning around, fastening to motor spindle/connector?

 

[berkeman]

TL;DR Summary: How is the keyless drill chuck can have locking torque great enough

How is the working principle of keyless drill chuck, the inventor confidently estimated that it'd have locking torque great enough as the same as to the keyed one just by turning around, fastening to motor spindle/connector?

Please, please always include links to what you want to discuss! Which keyless drill chuck? Like the one on my cordless drill? Or do you have some different one in mind? Which inventor?

 

[Baluncore]

The keyless chuck has a finer thread than a keyed chuck.
To lock onto the drill shank, the keyless chuck requires less torque, but more turns.

 

[berkeman]

The keyless chuck has a finer thread than a keyed chuck.
To lock onto the drill shank, the keyless chuck requires less torque, but more turns.

Well the OP is likely in a timezone where they are asleep right now, but it seems like the keyless chuck on my cordless drill has a radius comparable to the key on my regular drill press. So it takes about the same torque to lock each, no?

 

[Baluncore]

So it takes about the same torque to lock each, no?

No. A bigger outer diameter will reduce the grip needed to apply the same torque. The key provides a leverage advantage that permits the keyed chuck to be smaller.
The three tapered jaws in the chuck are advanced by a screw thread, along a cone of the same angle as the jaws.
A more gentle cone would require a longer chuck.
The finer thread advances more slowly per turn, with less torque.