A simple reducer of 1:76 using a combination of bevel gears, slightly different (76 vs 75 teeth).
Red gear is fixed, input is green arm and output is blue gear.
Video at https://youtu.be/TqpcVZTlYt8.
Schemes at https://br.pinterest.com/pin/479070479118695671/ and https://br.pinterest.com/pin/479070479118695675/.