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K-Series Maintenance

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K Series Cylinder Maintenance Instructions
Description Item
1 ** Wiper 18 Retainer Cap
2 Rod Bearing 19 Retainer Ring
3 Bushing Screws (4) 20 * Piston Rod
4 ** Rod Seal 21 Rod Bushing
5 ** O-Ring 22 Tie Rod Nuts (4)
6 a Cylinder Tube Seal 23 Lock Washers (4)
7 Cylinder Tube 24 Front Head
8 Front Cushion Assembly 25 Tie Rod (4)
9 Front spring Retainer 26 Retainer Ring
10 * Piston 27 * Piston O-Ring
11 a Piston U-Cup 28 * Piston Retainer
12 a Piston Bearing Strip 29 Cushion Guide
13 a Piston Seal 30 Cushion Screw Seal
14 * Piston Nut 31 Cushion Screw
15 Rear Cushion Assembly 32 Cushion Nut
16 a Cylinder Tube Seal 33 Washer
17 Rear Head 34 Thrust Washer
* Available as factory assembled only
** Available as rod seal kit only.
a Available as piston seal kit only

NOTE: Cylinder life is directly dependent on proper installation and air preparation.


Cylinders are not structural units and they are designed only to push and pull. The piston rod must be properly aligned with the mating part in both the extended and retracted position. Any misalignment will cause interference and shorten the cylinder life. Air lines must be free of all contamination. An air line filter should be used. The air supply must be clean and free of moisture. Proper lubrication is also recommended.


When rebuilding cylinders, make sure all parts are clean before reassembly and avoid introducing any dirt or chips into the cylinder. Check the piston rod (17) and the cylinder tube (7) for damage and replace either if necessary before proceeding. Pre-lubrication of all seals prior to re-assembly is recommended for ease of installation.

To Replace the Rod Seals

5/8" Diameter Rods

Remove any rod clevis or jam nut from the piston rod end(20). Remove the bushing screws (3), and slide the bushing (21) over the piston rod. Insert a new U-cup (4), bearing (2), and wiper (1) into a new bushing (21).


Install the new bushing assembly over the piston rod, taking care in passing it over the threaded part of the piston rod. Install new bushing screws and tighten firmly.

1" and Larger Diameter Rods

Disassemble as above, except remove the U-cup (4) from the front head. Install a new U-cup over the rod, taking care in passing it over the threaded part of the rod. Install new bushing screws and tighten firmly

To Replace the Piston Seals

Remove the front head (24) by unscrewing four tie rod nuts (22), removing the lock washers (23) and lifting the front head off the cylinder tube (7). Remove the piston rod/cylinder tube assembly from the rear head (17) and pull the piston rod assembly from the tube (7). Remove the piston U-cups (11 & 13), and the piston bearing strip (12).


IMPORTANT: Install new U-cups, making sure that the lips of the seals face away from each other.


Use grease to hold the new bearing strip (12) in place, and insert the piston rod assembly back into the cylinder tube.


NOTE: It may be necessary to temporarily compress the first piston U-cup to allow it to enter the tube. Make sure the bearing strip is not pinched between the tube and piston.


Install new cylinder tube seals (6) into the heads, and reinstall the cylinder tube. This is best done in the vertical position, with the blind end cover down. Make sure the tie rod nuts (22) and lockwashers (23) are installed on the short threaded end of the tie rods. Retighten the tie rods using equal torque on each rod per the chart below.

Bore Size Torque
1", 1 1/2"  8-10 ft.lbs.
2", 2 1/2", 3 1/4" 15-19 ft.lbs.
4", 5" 22-25 ft.lbs.
6", 8" 70-75 ft.lbs

To see the full list of mounting options and measurements download the datasheet.

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