Hydraulic pump question

I'm trying to get a pump for my Melroe M500. I got one from northerntool but it's too small. Most of the bigger ones have 4000 PSI rating and the Melroe manual says that the system pressure relief is set at 1800. So would 4000 PSI do damage? The pumps with lower PSI have less than the minimum 9 GPM that I need. Thanks for any help.

OldMachinist said:

http://www.loaderpartssource.com/bobcat-parts/bobcat-hydraulic-pumps/hydraulic-gear-pump-for-bobcat-m500.html

Click to expand...

The 4,000 PSI rating is just how much the pump can provide. As your relief will be set to 1,800 it will lower the output to that value. The way i see it, the pump should last longer as it's essentially running half of its rated pressure so less load on it.