Please make sure your printer prints accurate, and makes good supports.
I tested the small parts with 3 printers from different manufacturers, and got 3 slightly different result at the fittings, so please feel free to sand the problematic parts if something feels like it's too tight.

In the file name the number with an 'X' indicates how many copy you will need from that part.

To connect:
-'main shaft' and 'lower connect': shorter arms of main shaft need to be connected with the rounded side of the lower connect. Join these parts by pushing a pointed piece of 1.75mm filament through the holes. (other end of lower connect with the opened joint needs to face upward, longer arms of main shaft need to be horizontal, shorter arms need to be vertical and face down)

-place the 'lift arm inside' in the housing. The bend of the fork needs to face the bottom.

To glue:
-hidraulic fixer and housing:
there is two bigger face of the 'hidraulic fixer' part. Glue the smaller face to the top and inside of the 'housing' part (to get a continuous line on the opening of housing and on the edge of the fixer) after you placed the 'hidraulic' between them. Make sure the small ring on the hidraulic part stays outside of the housing.

-front wheels and front wheel shaft:
Check if u need to glue them, in some cases they can fit fix each other without glue too.
if no: glue them together after you placed the shaft in the hole on the bottom of the 'housing'.

-lift arm and lift arm inside:
there is only one possible way to glue them :D

-hidraulic and body
glue the small ring to the body after you assembled the whole pallet truck. It is an "only one way" move, again. ;)

Check and download also the 1:1 scaled pallet to the pallet truck!

Happy printing and have fun!