| Parameter | Specification |
|---|---|
| COGENG Part Number | 4649050 |
| OEM Equivalent | Hitachi 4649050 |
| Product Type | Hydraulic Cylinder Seal Kit |
| Application | Arm (Dipper) Cylinder |
| Kit Type | Complete overhaul seal kit |
| Compatible Models | Hitachi ZX240-3, ZX250-3 Excavators |
| Brand | Part Number |
|---|---|
| COGENG | 4649050 |
| Hitachi | 4649050 |
| Interchange | 4649051, 4649052, 4649053, 4652954 |
| Parameter | Typical Specification |
|---|---|
| Cylinder Type | Arm (Dipper) Cylinder |
| Bore Diameter | 110-120 mm (OEM specific) |
| Rod Diameter | 65-75 mm (OEM specific) |
| Stroke | 1100-1300 mm |
| Working Pressure | 320-350 bar (4,640-5,075 psi) |
| Component | Material Grade | Hardness | Temperature Range |
|---|---|---|---|
| Piston Seals | Polyurethane (PU) | 90-92 Shore A | -35°C to +110°C |
| Rod Seals | NBR + PTFE coating | 85 Shore A | -40°C to +120°C |
| Wiper Seals | Polyurethane (PU) | 88-90 Shore A | -35°C to +100°C |
| O-Rings | HNBR (Zetpol) | 70 Shore A | -40°C to +150°C |
| Wear Rings | PTFE + Bronze filler | — | -50°C to +200°C |
| Backup Rings | Nylon 66 (Glass filled) | — | -40°C to +120°C |
| Buffer Seals | Polyurethane | 90 Shore A | -35°C to +110°C |
| Parameter | Rating |
|---|---|
| Maximum Pressure | 350 bar (5,075 psi) |
| Operating Temperature | -40°C to +120°C |
| Fluid Compatibility | Mineral oil, synthetic hydraulic fluids |
| Seal Speed Rating | Up to 0.5 m/s |
| Service Life | 5,000+ operating hours |
| Item | Description | Quantity | Material |
|---|---|---|---|
| 1 | Piston Seal (Primary) | 2 | Polyurethane |
| 2 | Rod Seal (Step-cut) | 2 | NBR + PTFE |
| 3 | Wiper Seal (Double-lipped) | 2 | Polyurethane |
| 4 | Buffer Seal | 2 | Polyurethane |
| 5 | Wear Ring (Piston) | 2 | PTFE Composite |
| 6 | Wear Ring (Gland) | 2 | PTFE Composite |
| 7 | O-Ring (Gland to barrel) | 2 | HNBR |
| 8 | O-Ring (Piston to rod) | 2 | HNBR |
| 9 | O-Ring (End cap) | 4 | HNBR |
| 10 | Backup Ring (Various sizes) | 4 | Nylon 66 |
| 11 | Dust Seal (Rod wiper) | 2 | Polyurethane |
| Parameter | Specification |
|---|---|
| Model | Hitachi ZX240-3 Excavator |
| Type | 24-ton Crawler Excavator |
| Series | Dash 3 (Tier 3 / Stage IIIA) |
| Engine | Isuzu AH-4HK1X |
| Engine Power | 125-135 kW (168-181 HP) |
| Operating Weight | 24,000 - 26,000 kg |
| NO | Number | Name | Qty |
| 1 | 1110501 | . TUBE; CYLINDER ASSEMBLY | 1 |
| 1A | - | .. TUBE; CYLINDER | 1 |
| 1B | 4397790 | .. BUSHING; PIN | 2 |
| 2 | 974302 | . ROD; PISTON ASSEMBLY | 1 |
| 2A | - | .. ROD; PISTON | 1 |
| 2B | 4397790 | .. BUSHING; PIN | 2 |
| 3 | 974305 | . HEAD; CYLINDER | 1 |
| 4 | 836104 | . BUSHING | 1 |
| 5 | 208504 | . RING; RETAINING | 1 |
| 6 | 974306 | . RING; BUFFER | 1 |
| 7 | 974307 | . U-RING | 1 |
| 8 | 836107 | . RING; BACK-UP | 1 |
| 9 | 807904 | . RING; WIPER | 1 |
| 10 | A811135 | . O-RING | 1 |
| 11 | 679904 | . RING; BACK-UP | 1 |
| 12 | 219305 | . BOLT; SOCKET | 12 |
| 13 | 836108 | . BEARING; CUSHION | 1 |
| 14 | 962006 | . SEAL | 1 |
| 15 | 974308 | . PISTON | 1 |
| 16 | 224106 | . RING; SEAL ASSEMBLY | 1 |
| 16A | - | .. RING; SEAL | 1 |
| 16B | - | .. O-RING | 1 |
| 17 | 880605 | . RING; BACK-UP | 2 |
| 18 | 960302 | . RING; SLIDE | 2 |
| 19 | 224108 | . RING; SLIDE | 2 |
| 20 | 352715 | . SCREW; SET | 1 |
| 21 | 104404 | . BALL | 1 |
| 22 | 974309 | . BEARING; CUSHION | 1 |
| 23 | 937410 | . SEAL; CUSHION | 1 |
| 24 | 492212 | . STOPPER | 2 |
| 25 | 492213 | . RING; RETAINING | 1 |
| 27 | 4067901 | . SEAL; DUST | 4 |
| 28 | 1110601 | . PIPE | 1 |
| 29 | 1110502 | . PIPE | 1 |
| 30 | 984614 | . O-RING | 2 |
| 31 | M341236 | . BOLT; SOCKET | 8 |
| 32-39 | 1110503 | . KIT; BAND | 1 |
| 32 | 1110504 | .. BAND | 1 |
| 33 | 373419 | .. BAND | 1 |
| 34 | J901035 | .. BOLT | 2 |
| 35 | A590910 | .. WASHER | 2 |
| 36 | 309219 | .. CLAMP; PIPE | 1 |
| 37 | 224115 | .. BOLT | 2 |
| 38 | 208516 | .. WASHER; SPRING | 2 |
| 39 | 309021 | .. HOLDER | 1 |
| 40 | 271312 | . FITTING; GREASE | 1 |
| 100 | 4649050 | KIT; SEAL | 1 |
Q: What Hitachi models use the 4649050 arm cylinder seal kit?
A: The COGENG 4649050 arm cylinder seal kit is specifically designed to fit the arm cylinder on Hitachi ZX240-3 and ZX250-3 excavator models. Always verify this part number against your machine's parts manual or the cylinder's original seal kit reference to confirm exact compatibility, as cylinder specifications may vary by serial number range.
Q: What are the symptoms of failing arm cylinder seals on a Hitachi ZX240-3 or ZX250-3?
A: Common symptoms include visible hydraulic oil leaking from the arm cylinder rod or gland area, reduced arm digging and lifting force, cylinder drift where the arm slowly drops under load, jerky or uneven arm movement, and external oil accumulation around the cylinder assembly. Addressing seal failure promptly helps prevent internal cylinder scoring and more costly repairs.
Q: What is included in the COGENG 4649050 arm cylinder seal kit?
A: Each complete seal kit includes piston seals, rod seals, wiper seals, O-rings, backup rings, and gland seals needed for a full arm cylinder overhaul. COGENG kits are manufactured using high-grade materials that meet or exceed OEM specifications for abrasion resistance, temperature tolerance, and extended service life in demanding excavator applications.
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