This is old school - they don't make pumps like this any more - the
amount of iron spent to build this relatively small pump (105 cm3 or
6.4 cu3) would be enough to build at least two equally sized pumps
today.
Pumps like this (another good example would be the
Hydromatik A2V) remind me of my old old country - the USSR - heavy like
hell, robust and ugly. If I were to give this pump a name, I would name
it Ivan Drago. This is very accurate, by the way, because those who
have to google Ivan Drago most certainly have never worked with a PR105
or an A2V...
This one decided to "exit in style", which can be seen on the images. This used to be a piston, and this, well, used to be a piston, too...