BRACKET A 8J4266 - Caterpillar

VA Boom Cylinder Features
Illustration 1 g03710921
Hydraulic cylinder (typical example)
(1) Boom hydraulic cylinder
(2) Control valve The VA boom hydraulic cylinder has the following features:
Auto and manual grease ports on each end
Heavy-duty manganese bronze bushings
Grease wiper seals on pins to retain grease and keep out contamination
Induction hardened, chrome rod and chrome barrel
Bolt on gland cap
Heavy duty high-pressure oil sealing system
Safety load holding valve on bore side to prevent cylinder retract in the event of hose rupture
Pressure equalizing lines used for even loading
Rod side pilot signal release oil from bore to tank
Air release valves to release air from long pilot linesPiston Seals
Illustration 2 g03711338
(1) Wear bands
(2) Piston seal (OD)
(3) Piston ring (ID)
(4) Cylinder ring
(5) Seal o-ring Wear bands (1) prevent the piston from touching the ID of the barrel.Piston seal (OD) (2) capped t-seal blocks oil from by-passing through the piston between the barrel ID and the piston OD.Piston ring (ID) (3) blocks oil from by-passing through the piston between piston ID and the rod OD.Rod Seals
Illustration 3 g03711373
(1) O-ring
(2) Ring-back up
(3) Retaining ring
(4) Wear band
(5) Seal buffer
(6) Seal-cup
(7) Ring-back up
(8) Seal Wear bands (4) prevent the rod from touching the ID of the gland head.O-ring (1) and backup Ring (2) blocks oil from bypassing through the gland head between the gland head and barrel.Buffer seal (5) is the first seal that sees pressure. The purpose is to reduce pressure spikes on the rod seal and increasing the life expectancy.Rod seal (6) deep z seal blocks oil from bypassing externally through the gland head. The seal also blocks external liquid from entering the cylinder.Wiper (8) excluder has a lip seal that is pointed outward to wipe off debris of the rod. The purpose is to prevent contamination from entering the cylinder.