Knight Hawk Supply
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Cessna Piston Pumps and Repair Parts, Hydraulic Motors, Pumps, and Valves

Installation Requirements

Install piston pumps in such a position that the case drain assures an oil level at or above unit center line.

Oil level must be at center line or above before starting piston pump.

Provide a case drain line of adequate size to limit the case pressure to 25 PSI maximum.

Filtration is recommended.

The combined torque required to turn two or more pumps must not exceed the torque rating of the input drive shaft of the front piston pump.

Cleanliness

In systems that use Cessna medium duty piston pumps the fluid must be maintained at ISO Cleanliness Code 18/13 or better per SAE J1165. This code allows a maximum of 2,500 particles per milliliter greater than 5 mm and a maximum of 80 particles per milliliter greater than 15 mm. When components with different cleanliness requirements are used in the same system, the cleanest standard should be applied.

Fluid Recommendations

In hydraulic systems that use Cessna Medium Duty piston pumps and motors, the optimum viscosity range is 10 - 39 cSt [60 - 180 SUS], at normal operating temperatures. Viscosity should never fall below 6 cSt [45 SUS]. At the lowest expected start-up temperature, the viscosity, with a non-charge system, should not exceed 432 cSt [2,000 SUS].