Determining the proper grease fill amount for hydraulic cylinder bushings like on an excavator hydraulic bucket cylinder typically requires the following steps:
Identify the cylinder type and size.
Measure the cylinder bore diameter and stroke length to determine the total volume of the cylinder.
Calculate the volume of the piston rod and blind end (open end) sections.
The piston rod volume is pi x rod diameter^2 x stroke length / 4. Blind end volume is pi x bore diameter^2 x blind end length / 4. Subtract these from the total cylinder volume.
The remaining volume is the volume of the cylinder tube that houses the hydraulic piston. This is the volume you will pack with grease.
Decide on a target percentage fill, typically 25-35% of the cylinder tube volume for most hydraulic cylinders.
So if your cylinder tube volume is 100 cu in., aim for filling 25-35 cu in. of space with grease.
Select a grease with the proper rating for the cylinder pressures and temperatures. Typical hydraulic cylinder greases are NLGI #2 or #3.
Pack the grease into the cylinder tube until you reach your targeted fill volume.
Use a grease gun, manual ram, or grease pistol to apply the grease through the end seals or via a zerk fitting.
Wipe off any excess grease from the exterior of the cylinder.
Ensure all seals and seals surfaces remain clean and free of grease.
Repeat steps 1 through 7 for any other hydraulic cylinder grease fill applications on your excavator.
Be sure to follow your excavator manufacturer’s recommendations for regreasing intervals based on hours of operation and environmental conditions. Typically 6-18 months for normal use.