Abrasive wear caused by fine particles

Dirt can enter the system through worn seals,  if the system is serviced in dusty conditions or with dirty equipment.  Always wipe tank caps, funnels and all areas around the filler neck clean before opening the tank.  Immediately cover all disconnected lines, fittings and openings.  Check the rod wiper seals to be sure they are operating effectively.

The effectiveness of the cylinder rod wiper seals can be checked as follows:

V-Type Rod Packings:

• Extend the cylinder rod (WARNING: When checking lift cylinder wipers, block the bucket securely in a raised position)
• Remove the bolts securing the wiper seal retainer to the cylinder head
• Coat the rod with grease
• Slide the retainer and wiper seal up the rod
• Examine the rod.  The wiper should wipe the rod clean.  If the wiper does not remove all the grease 360 degrees around the rod, it is too loose and should not be used

These rod seal arrangements do not have a retainer on the cylinder head that can be removed for checking the wiper seal.  The wiper seal is mounted inside the counterbore of the head and can be inspected visually.  A better check can be made trying to insert a .001" or .002" (0,025 or 0,0050 mm) feeler gauge between the wiper seal lip and the rod.  If the wiper seal is effective, the feeler gauge cannot be inserted.  The rod should not be in a scratched, scored or otherwise damaged condition.

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.

NOTE: 1 micron = 1/1000 millimeter or .0000394 inches