+ 90 ° means tighten the screw through 90 degrees, which is another quarter turn.
If the record is for several bolts, then you first tighten all of them with a torque, and then all of them by a given angle. Each additional plus is another tightening series for all bolts (e.g. 25Nm + 60 ° + 60 ° + 15 °). Thanks to this, you tighten them gradually and evenly. This method significantly reduces the inaccuracies, because instead of 20Nm + 90 °, you could write 130Nm. But with such a large torque, such things as whether the bolt is "black" or galvanized, whether the thread is dry or wetted with oil, and the same with the contact of the screw head with the screwed element have a big influence.
This notation is often used for screws tightened so much that the yield point of the screw material is exceeded - you tighten, the screw "starts to flow" and the torque increases very little. You are missing a few Nm on the wrench and you never reach them, because the screw breaks off (that's why such screws need to be replaced / used only once).
When tightening "on an angle", the first torque is often small, so the errors due to friction of the thread and head are not so large.
Here you can read the study about the head bolts.
birch , there are sprockets in the catalog as separate parts, so you can only buy sprocket and chain. I just don't know if the new gear will fit the old pump, because when they upgraded, they changed everything, including the pump.
This is exactly the answer I expected. Only now everything is clear.
