Nice RD400 Instructions And Warnings For Installation And Use page 8

h - manually open the gate leaf fully
i - place the first section of the rack on the gearmotor's
pinion: make sure that it corresponds to the start of the
gate leaf and that there is a gap of 1–2 mm between the
rack and the pinion (this so as to prevent the gate leaf
h
weight from bearing on the gearmotor)
g
h
l - secure the rack section
1÷2 mm
m - slide the gate by hand and, using the pinion as a ref-
erence, secure the other sections of the rack
6 – English