Thank you very much for your input and time BobH, Pawel66 and VikDasor. Here is summary of my research. This is all very interesting, and it looks like there are two engineering solutions for this assembly because there are different steering pumps - one with thread in the housing and the other without thread in the pump housing. I’m talking about Bolt No 45 in schematic shared by Pawell66. Clamping bolt No 43 in the same schematic and also picture shared by VikDasor is the same in all cases and it is all clear about it.
1. In the manual BobH shared which is from 230SL there is schematic (please see picture attached) steering pump does not have thread in the housing and hence there is Hex-head screw (22), then washer (23), then another washer (23), then tightening screw (clamping bolt) (24), then locking plate (26) (part No A1274660073) and then hex nut (27). This is also corresponds to schematic I found on W110 (please see picture attached). My concern was that when you tighten the tightening screw then the clamp damages thread of Hex-head screw No22/No634, which would be an issue if steering pump would have threaded housing, because when you would screw it out the damaged thread would also damage the thread in the pump housing.
2. In the schematic Pawel66 shared there is just the Bolt (45) and washer (39) (there isn’t any locking plate and hex nut). This is intended for steering pumps with thread in the pump’s housing. Which is what I have. Bolt 45 (part No A1279900101) has no thread at the end and end is in smaller diameter. The clamping bolt 43 is mounted on no thread part of Bolt 45. In such case it does not damage the thread and resolve above mentioned issue. But the question remains how clamping bolt 43 is secured on the Bolt 45, does it remain there (does not slip off) just by tightened force, meaning there is nothing at the end of Bolt 45?
