OK - but that wouldn't make much of a coin press. I feel it safe to say they were referring to the weight of the machine.
If the press is 900 pounds then it probably does something like 40-70 tons, I would think that is most likely.
A press that could deliver 40 to 70 tons of pressure per square inch doesn't make much of a coining press either. It takes about 70 tons to strike a quarter so larger coins would not be possible and a quarter sized coin would be pushing it. The law differentiates between coins and currency. Currency and obligations are printed items, coins are struck.