SYSTEM COMPONENT
TYPICAL CLEARANCE (Microns)
Gear Pump
Gear to Side Plate Gear Tip to Case
0.5 to 5 0.5 to 5
Vane Pump
Tip of Vane Sides of Vane
0.5 to 1 5 to 13
Piston Pump
Piston to Bore Valve Plate to Cylinder
5 to 40 0.5 to 5
Servo-Valve
Orifice Flapper Wall Spool-Sleeve
130 to 450 18 to 63 1 to 4
Control Valve
Orifice Spool-Sleeve Disc Type Poppet Type
130 to 10,000 1 to 23 0.5 to 1 13 to 40
Actuator Hydrostatic Bearing Anti-friction Bearings Side Bearing
Once the target is selected, develop a good maintenance program that includes hydraulic oil testing. The testing will provide you with information that can tell you the health of your system. If testing shows a foreign substance in the oil or a high particle count, then you know it is time for system repairs. Confirmation Cleanliness Levels By Testing Despite efforts to totally remove
all of the contaminant in a hydraulic hose system, some contamination remains even after the most robust cleaning or flushing techniques are applied. Contamination can be quantified to better understand the resulting cleanliness level of the hydraulic system. The customer may require a specified cleanliness level.
methods to measure the contamination level within a component, circuit, or system.
The International Standards Organization (ISO) has established three principal
Usually a combination of the above testing methods is required to maintain the target
• ISO 4405 (Gravimetric Measurement) • ISO 4406 (Particle Size Distribution) • ISO 4407 (Maximum Particle Size Analysis
50 to 250 1 to 25 1.5 to 10 1.5 to 10
cleanliness levels The author R Rajasekhar is General Manager Marketing & Training in Gates India Pvt Ltd. For more details reach Gates India Pvt ltd at www.gates.com/ india or follow on LinkedIn: company/gates-india to help eliminate expensive downtime and prevent dangerous, environmentally devastating and expensive accidents.
The fine particles that cause abrasive wear are usually not visible to the eye. The size of these particles is about 40 microns. Their relative size as compared to a human hair is shown below. Oil containing particles of this size can actually look clean while having enough abrasive particles to cause pump failure
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www.martupdate.com
August 2016