If anybody feels like there are copyright issues, do contact me, and we shall deal with it.
Gear Pump Displacement Calculator
Interactive O-ring Table
Cylinder-Mounted Pilot-to-Open Check Valve Interactive Pressure Chart
Interactive Nomogram for Sizing Hydraulic Hoses
Maximum Pressure Calculator for Steel Pipes and Cylinder Tubes
External-Pilot-Operated Over-center Valve Calculator (+ Some Tips)
Hydraulic Seal and Seal Kit Database
Recommended Dimensions for Heads of ISO 6162-1/2 (SAE J518-61/62) Flange Connectors
Orifice Pressure Drop Calculator
Basic Module - a very nice basic hydraulics course
Facts, worth knowing about hydraulics from Danfoss
Fluid Power Grafic Symbols
Rexroth Axial Piston Units Training Course
Hydraulics Hints And Troubleshooting Guide
Gear Pumps Analysis and Troubleshooting
Logical Troubleshooting in Hydraulic Systems
Lubricants and Hydraulic Fluids
Hydraulic Filtration - The handbook of hydraulic filtration
The Micron Rating for Media in Fluid Filters