Performance Testing of Hydraulic Power Transmission Fluids

Southwest Research Institute has extensive experience in the performance testing of hydraulic power transmission fluids. With fully equipped laboratories and an experienced staff of engineers, technicians, and support personnel, Southwest Research Institute:

• Measures the ability of hydraulic oils to deliver maximum performance
• Qualifies hydraulic oils for antiwear protection in hydraulic pumps
• Determines the ability of hydraulic fluids to maintain rated flow in pumps at high pressure in the presence of water

Denison P46 Test Stand

SwRI employs a high-pressure Denison pump that measures the ability of hydraulic oils to deliver maximum performance as part of the Denison HF-O Standard. Tests determine oil effects on flow, deposits, and wear in a 46-series piston pump. Each test is run at 2,400 rpm for 60 hours at 71 degrees Celsius, followed by 40 hours of operation at 99 degrees Celsius. At 60 hours, the pump is disassembled and inspected for evidence of distress.

Hydraulic fluid performance is evaluated in the Denison P46 Piston Pump Test Stand.

Vickers Test Stands

The demand for antiwear hydraulic fluids for use in mobile equipment utilizing high-performance hydraulic pumps is escalating rapidly, and equipment breakdowns are costly. Hydraulic equipment failure can be reduced through the use of fluids that provide good antiwear protection in hydraulic pumps.

Two tests for the qualification of hydraulic oils used in Vickers vane pumps are offered at SwRI:

• Standardized procedure ASTM D-2882 determines antiwear properties using an electric motor-driven Vickers 104-C hydraulic pump. Antiwear performance is determined through measurement of weight loss of pump vanes and cam rings after 100 hours of continuous operation, followed by visual inspection for scoring and scuffing.
  
  
• The Vickers 35VQ25A pump test (Form M-2952-S, revised 8/88) requires 50 hours of operation at maximum rated pressure and speed. This test is required for the Caterpillar TO-4 specification.

Sundstrand Dynamic Corrosion Test Stand

The Sundstrand Series 22 axial flow pump, driven by a six-cylinder diesel engine, is a highly specialized system that can determine the ability of hydraulic fluids to maintain rated flow at high pressure in the presence of water. Hydraulic pump efficiency can be degraded by a small amount of water in the hydraulic fluid if it causes dynamic corrosion of yellow metals in the pump. The Sundstrand pump is run at 5,000 psi at an outlet temperature of 82 degrees Celsius for 225 hours, with water added after the first 25 hours. Evaluations include:

• John Deere fluids
• ASTM multipurpose power transmission fluids
• Various hydraulic fluids

SwRI staff members examine pump hardware using an SPI Stereogold IV trinocular microscope system. Three-dimensional stereo zoom allows magnification up to 160 times. Real-time color video display facilitates simultaneous viewing of microscopic phenomena.

Specialized Testing

For nonstandardized hydraulic fluid or hydraulic hardware investigations, SwRI has developed a universal hydraulic test stand with the following capabilities:

• 0 to 2,500 rpm variable drive speeds
• Drive unit up to 200-400 hp
• Inline particle/debris measurement
• Inline fluid density measurement
• Pump driving torque measurement

This stand offers state-of-the-art computer data acquisition and control.

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