Hello
940/18 is a variation from the 940/29 using a 1-12 UNF. The difference is in the check valve.
It is the same version like the 940 but not with the 3/4-16 UNF Thread
The 940/18 was used in Farmer machines and Traktors and can be used as 940/29 replacment if everything else isn´t on hand
Grüsse