SET-BEARING 2138256 - Caterpillar

Head Seal Locations
Illustration 3 g01640536
Threaded gland with standard head seal
The head seal for the oversize threaded gland cylinder is the standard O-ring and back-up ring (1).
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Threaded crown with oval seal
The head seal for the oversize threaded-crown cylinder is an oval cross-section seal (2). The seal is located in the lead-in chamfer at the open end of the cylinder. The O-ring and back-up ring groove (A) in the head is left empty
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Bolted-Head Cylinder
Formerly, the head seal for the oversize bolted-head cylinder was the same oval seal (6) that is used in an oversize threaded-crown cylinder. The oversize bolted-head cylinder is now sealed at the head joint (3) by an O-ring (4). This O-ring (4) provides a more effective seal than the oval head seal. The groove (5) for the stock seal is left empty.Seal Installation Information
Rod Seal Installation
Illustration 6 g01644830
Install buffer seal (2) by hand. The sealing lip of the buffer seal should face the pressure side of the cylinder. The seal will take on a kidney shape during installation. Then, install the back-up ring (3). The backup ring should be installed closest to the rod eye end. Make sure that you do not twist the back-up ring.
Next, install the U-cup seal (6) next. Install the U-cup seal by hand. The "U" of the U-cupped seal should face toward the piston.
The head wear ring (1) is rigid and the wear ring is split to aid in assembly. Compress head wear ring (1) and slide the head wear ring down into position until the wear ring snaps into place.
Use the following procedure to install wiper seal (8).Note: The wiper seal (8) can be a press-in style that uses a metal shell or the wiper seal can be a snap-in style. The snap-in style does not require the use of bearing mount compound.
Scuff the surface of the counterbore in the head as well as the outside diameter of the wiper seal's (8) metal shell with emery cloth.
Clean the counterbore in the head and the outside diameter of the wiper seal metal shell with 6V-1541 Quick Cure Primer. Clean the counterbore and the metal shell until neither of the components discolor a clean white towel.Note: The metal shell of the wiper seal is coated with a corrosion inhibitor. This coating may prevent proper bonding of the wiper seal to the cylinder head if the inhibitor is not removed. After cleaning, do not touch the counterbore or the metal shell because the oil from your fingers may prevent a good bond. Handle the seal by the lip only.
Apply 6V-1541 Quick Cure Primer on the counterbore and the metal shell. Allow the primer to dry. The primer will dry in approximately 30 seconds.
Apply 7M-7456 Bearing Mount Compound evenly, but do not apply the Bearing Mount Compound excessively. Apply Bearing Mount Compound to the counterbore and to the metal shell. Do NOT allow the Bearing Mount Compound to contact the sealing lip.
Press wiper seal (8) into the cylinder head. Make sure that