SKU SK-BC331-ARM-B
Bobcat 331 Arm Cylinder Seal Kit — S/N 512911001 & Above
completeFull service kitthreaded external gland
The later 331 arm cylinder went to a 2.75 in bore. Same rod, different piston seals — the earlier kit will not seal this cylinder. Check your serial plate before ordering.
What's in this kit
Every seal in the kit, with its material and size.
| # | Qty | Part | Material | ID | OD / cross-section | Height | Shore A |
|---|---|---|---|---|---|---|---|
| 1 | 1 | Rod sealRS-1500-2000-313 · polypak | Polyurethane | 1.5" (38.1 mm) | 2" (50.8 mm) | 0.313" (7.95 mm) | 90 |
| 2 | 1 | Buffer sealBS-1500-2000-250 · buffer | PTFE / NBR | 1.5" (38.1 mm) | 2" (50.8 mm) | 0.25" (6.35 mm) | — |
| 3 | 1 | WiperWP-1500-1875-250 · dust wiper | Polyurethane | 1.5" (38.1 mm) | 1.875" (47.63 mm) | 0.25" (6.35 mm) | 90 |
| 4 | 1 | Rod bushingRB-1500-1625-375 · guide band | Bronze-filled PTFE | 1.5" (38.1 mm) | 1.625" (41.27 mm) | 0.375" (9.53 mm) | — |
| 5 | 1 | Piston sealPS-2000-2750-375 · t-seal | Polyurethane | 2" (50.8 mm) | 2.75" (69.85 mm) | 0.375" (9.53 mm) | 90 |
| 6 | 1 | O-ringOR-2000-139 · energizer | Nitrile (NBR) | 2" (50.8 mm) | 0.139" (3.53 mm) | — | 70 |
| 7 | 2 | Wear ringWR-2500-2750-500 · guide band | Bronze-filled PTFE | 2.5" (63.5 mm) | 2.75" (69.85 mm) | 0.5" (12.7 mm) | — |
| 8 | 1 | O-ringOR-2875-139 · gland seal | Nitrile (NBR) | 2.875" (73.03 mm) | 0.139" (3.53 mm) | — | 90 |
| 9 | 2 | Backup ringBU-2875-3150-50 · backup | Nylon | 2.875" (73.03 mm) | 3.15" (80.01 mm) | 0.05" (1.27 mm) | — |
Cylinders this kit services
Bobcat 331 Arm Cylinder (S/N 512911001 & Above)
- OEM no.
- 7135778
- Bore
- 2.75" (69.85 mm)
- Rod
- 1.5" (38.1 mm)
- Stroke
- 22.5" (571.5 mm)
- Closed
- 35.4" (899.16 mm)
- Gland
- threaded external
- Port
- SAE ORB #6
- Rod eye
- spherical bearing
What this fits
| Machine | Serial range | Position |
|---|---|---|
| Bobcat 331 · E / G Series | S/N 512911001 & Above | Arm / Dipper |
Our kits are dimensional equivalents built from seals we buy in. They fit and replace the original. They are not OEM parts and carry no OEM branding.
Not finding it?
Not sure this is right?
Check it with a caliper before you buy — how to measure bore, rod and stroke covers the mistakes behind most wrong orders. Send us the numbers and a photo of the old seals and we’ll confirm the fit before you spend anything.
Request a kit