The Chief GP-PTO model is a gear pump designed for use on a tractor's Power Take-off (PTO). This line is offered in four displacement sizes, from 3.41 to 9.76in3/rev (56-160cm3/rev).The recommended working conditions are as follows: Filtration: 25 microns or betterInlet pressure 12 to 32 psi absoluteOil Viscosity: 6 to 200 cStAmbient Temperature: -8 to 130°F (-22 to 55°C)Oil Temperature:  -12 to 175°F (-25 to 80°C)Model Specific Information: Model: GP-PTO-7-540GPM: 7.4 (@ rated speed)CID: 3.41Ports: SAE-16/12Shaft: 1 3/8" Female spline, 6 toothRotation: Counterclockwise