Hydraulic cylinder seal kits are used to seal the gap between different parts of the hydraulic cylinder. The function of hydraulic cylinder seal kits is to prevent oil leakage, to assure the working pressure of the hydraulic system, to maintain its power.
Boom Cylinder seal kit is, as the name suggests, fitted into the boom cylinder.
There are regularly three cylinders for the excavator, boom cylinder, arm cylinder, bucket cylinder.
Arm cylinder is the top one, and it's usually be called as top cylinder;
The bucket cylinder is the one that connects and controls the bucket.
Boom cylinder is the one (or the two) near the cabin. Usually, there is one piece boom cylinder for the small excavator under 10-tun; the bigger excavator's two pieces boom cylinders. But there is an exception too when the driver will remove one piece for a special purpose, say at some particular working place, it is convenient to work by one cylinder. Soft remind: all refit job should be operated by an experienced technician.

Before installation, you must to clean first the place where the seals to be fitted, with tipical cleaner. And so the metal parts of the seal. Clean the counterbore and the metal shell until they not get a clean white towel changed color.

Be careful that not to touch the other parts of the seal with your fingure. Only to hold the seal with the lip in order to keep the seal clean and thus make sure the wiper seal could bond to the cylinder head properly.

Install vented buffer seal assembly. The seal assembly consists of one seal and one backup ring.
Install vented buffer seal in the correct groove of cylinder head . Seal has a groove for backup ring. The groove must face the rod end of the cylinder, to the correct assembly position.
Install backup ring in seal to the correct assembly position.