| Parameter |
Specification |
Notes |
| COGENG Part Number |
COGENG-991/20021-BH |
"BH" denotes Backhoe application |
| Replaces OEM Part No. |
JCB 991/20021 |
Direct 1:1 replacement |
| Rod Diameter |
40 mm (±0.10 mm) |
Critical for rod seal and wiper fit |
| Bore Diameter |
70 mm (±0.15 mm) |
Critical for piston seal and wear band fit |
| Primary Rod Seal |
Nitrile (NBR) with PTFE reinforcement |
Ensures zero-leak performance under high pressure |
| Primary Piston Seal |
Polyurethane (PU) |
Excellent abrasion and extrusion resistance |
| Wiper/Scraper |
Polyurethane (PU) |
Double-lipped design to exclude dirt and moisture |
| Wear Bands/Guide Rings |
PTFE-Filled Nylon |
Reduces friction and prevents metal-to-metal contact |
| O-Rings |
Nitrile (NBR) |
Reliable static sealing for all connections |
| Temperature Range |
-30°C to +100°C (-22°F to +212°F) |
Suitable for most operating environments |
| Pressure Rating |
Up to 35 MPa (5000 PSI) |
Designed for backhoe loader hydraulic systems |
| Fluid Compatibility |
Mineral-based and synthetic hydraulic oils |
Compatible with standard JCB fluids |
Decompose pictures
Parts list
| NO |
Number |
Name |
Qty |
|
556/60476 |
Ram assembly tilt, fixed |
1 |
| 1 |
:332/D4842 |
Kit - end cap assembly |
1 |
| 2 |
:590/40127 |
Rod piston |
1 |
| 2A |
::1207/0011 |
Bush |
1 |
| 3 |
:595/ 10027 |
Head piston |
1 |
| 4 |
:826/01182 |
Dowel |
1 |
| 7 |
:556/70476 |
Cylinder |
1 |
| 7A |
::1207/0019 |
Bush |
1 |
| 12 |
:1450/0001 |
Nipple Grease, Straight 1/8 BSP |
3 |
| 50 |
:991/20021 |
Kit-seal universal 70X40 |
1 |
Pre-Installation Checks:
Clean the cylinder exterior and work area thoroughly.
Compare old seals with new components to verify compatibility.
Inspect the rod, bore, and gland for scratches or wear. Polish minor imperfections with fine emery cloth.
Disassembly:
Mark the gland, piston, and tube for reassembly alignment.
Document seal order and orientation with photos.
Remove old seals carefully without damaging gland or piston grooves.
Seal Installation:
Lubricate all new seals and contact surfaces with clean hydraulic fluid.
Use soft-tipped tools or seal installation kits to avoid damaging seals.
Ensure seals are seated evenly in grooves without twists or rolls.
Reassembly & Testing:
Reassemble components in reverse order of disassembly.
Torque gland nuts and bolts to manufacturer specifications.
Cycle the cylinder slowly without load to seat the seals. Check for leaks and monitor fluid levels.
Frequently Asked QuestionsA. When will get the items after I place order?
Q. Once your payment is confirmed,we will arrange the goods within 1~4 days; if not in stock, we will inform you before placing the order?
A. If I only know the excavator model, but can not offer parts No.,what should I do ?
Q. If possible, you can send us pictures of old products, nameplate or the size for reference.
A. How can you guarantee the quality??
Q. We will 100% test the goods before delivery. We also support video inspection.
A. How long will it take to delivery to my address??
Q. The normal delivery time is 3-7 days, depending on which country you are in.?
A : Which delivery method will you choose?
Q : By sea, air or express(DHL,Fedex,TNT, UPS, EMS etc.)，Sometimes we will arrange as the customer's demand.
A: What's package? Can you give me the package according my requirement??
Q. We usually packed by standard exported box or carton. And yes we can pack as per your requirement.
A: Can the price be cheaper?
Q: Of course, you will be offered a good discount for a big amount.
A: Why should I choose to buy from you?
Q:Our advantages: 100% quality assurance, develop and manufature follow original ones;Quick response within 24 hours; Small order allowed;Reasonable stock and timely delivery;Neutral packing, customized packing are allowed. Positive customer feedback from abroad market;Excellent after-sales service.
A : Which payment terms can you accept?
Q : Paypal. Western Union, Bank Transfer, T/T...
