[020] Lego Technic - Two-way to One-way #02

this mechanism consists of a rotational input, a crank, and an output, an axle, behaving as follows:

if one rotates the input clockwise the output rotates clockwise with the same speed and torque

if one rotates the input anticlockwise the output also rotates clockwise with the same speed and torque

one cannot rotate the output anticlockwise, because it’s blocked

if one rotates the output clockwise the input remains idle

small angles of input do not translate in output motion

the mechanism behaves the same if one of the laterals gears is used as input, but with a 5:1 gear ratio

the principle of this mechanism is a double freewheel illustrated on the video:
‘Mechanism for converting two-way to one-way rotation 1c’ from youtube user thang010146 and also on the mechanism n° 49 on the 507 Mechanical Movements site

the only function that I’m aware of this mechanism is to power watches using the wearer’s movement: in mechanical ones to wind a spring and in quartz ones, coupled to a miniature electrical generator, to charge a capacitor or battery.

there is also an idea by Dr. Adrian Zurbuchen to power pacemakers, using the heart as input

the ratchet in this model consist of single axle 2 on a 16 tooth gear, I called it pin-ratchet® and I have invented this myself and I’m not aware of previous uses, if someone does, please let me know.

at the end of the video I show my previous model using my old ratchet technology, this model was developed to act as the great wheel of a clock. It shows an unanticipated characteristic: when rotated vigorously the ratchet pawls disengages, much like a centrifugal clutch

search on rebrickable to view the inventory of parts and instructions to make this model