Southworth Pallet Unloader, Installation, Operation & Maintenance Manual

Southworth Products

PUN Manual

PUN Manual

23

Remove the smaller O-ring which fits around the cylinder rod.

6.  Remove the gland from the cylinder rod by sliding it off of the end which holds the 

piston. Notice how the wiper ring sits in the gland. Note the positions of the quad ring 

and BU washer. Remove the wiper ring, quad ring and BU washer from the gland.

7.  Clean all of the surfaces on the gland.  Install a new quad ring and BU washer.  Install a 

new wiper ring in the correct orientation.  Coat the inner diameter of the gland with light 

grease and replace it on the rod.

Be careful not to install the wiper backwards.

8.  Clean the piston surfaces.  Install a new larger O-ring and leather BU washer on the 

piston.  Install a new piston ring.  Install a new smaller O-ring.  Attach the piston to the 

rod and tighten the large nut.

9.  Clean the bore of the cylinder tube thoroughly.  Inspect the bore of the tube for 

scratches which run up and down, along the length of the cylinder.  If you do see any 

scratches, hone the inner surface of the cylinder.  Be sure to clean the tube thoroughly 

after you do this.

10. Lubricate the inner diameter of the cylinder tube with a light coating of hydraulic oil.  

Carefully insert the piston and rod back into the cylinder.  Be very careful not to damage 

the piston ring, O-ring or BU washer as you do this.  It may be helpful to tip the rod 

assembly and twist it as you slide it into the cylinder.  Once the piston is inside the 

cylinder, it should slide easily.

11. Slide the gland assembly into the cylinder.  Rotate the gland so the port lines up with 

the hole in the cylinder tube.  Install a new snap ring.  Compress the snap ring, tap the 

gland into place, then relax the snap ring.  Be sure that the snap ring is in place in the 

groove.

12. Install the cylinder in the unit as described below.

8.8  Replacing a Cylinder

Before beginning this procedure, please read and understand this entire section. 

1.  Before beginning, read steps 2 through 4 in the procedure “Removing a Cylinder” 

listed above.

2. 

Place the cylinder near the point where it will fit into the mechanism.  Be sure the 

cylinder ports are oriented correctly.

3.  Align the lower cylinder with each lower cylinder clevis and insert the lower 

cylinder clevis pin. Be careful! The cylinder is heavy!  Replace the “keeper” and 

secure it with the button-head cap screws (supplied). Repeat the same procedure 

to replace and secure the clevis pin for the upper cylinder.