I changed the seals on my Dake 50 ton, the gauge reads in tons for a 5” ram. The large size of the housing is for the oil reservoir.
An interesting fact I found out about the 50 ton size is that it can produce 50 tons of pressure but its actual working range is best at up to 25 tons. I had to make a longer handle when I needed to use a fairly high pressure, just above 30 tons, the frame seemed like it was not quite up to the task of going to the full 50.
It was also quite a chore to pump it over 30 tons, needed a lot of force on the lever.
The good thing is the longer your cheater bar the farther away you are from the danger zone......
I added a small hydraulic pump to my press and it was only capable of 1800 psi, which translated directly to 18 tons under the ram. So the hand pump is capable of 5000psi. (which still works) The electric pump is a very nice addition to the press and I rarely need more than 18 tons for my work.
I am pretty sure I read about a PM’er who added a quick change system with a variety of gauges to his press so he could use the press for very low pressures, the tonnage gauge on mine is useless for light work. I have usually overdone it before the gauge needle moves. I did add an adjustable pressure relief valve and that works very well to do consistent bending.