The 380901056 Lock Plate is a genuine OEM heavy‑duty locking tab manufactured by XCMG for motor grader fastening systems, bearing retainers, and pivot pin locking applications. This precision‑stamped steel plate is designed to mechanically lock nuts, bolts, or retaining rings after final torque, preventing loosening under severe vibration, shock loads, and temperature cycling on GR series motor graders (GR135, GR165, GR180, GR2003, GR215, GR300, GR350). Constructed from high‑strength spring steel with a corrosion‑resistant zinc‑plated finish, the 380901056 lock plate ensures critical fasteners remain secure in demanding grading environments.
The lock plate 380901056 features a precisely formed tab that bends against a flat of the nut or bolt head, while a second tab engages a stationary slot or edge on the mating component. This positive mechanical lock eliminates the need for adhesive threadlockers or spring washers, which can fail under extreme vibration. The plate is commonly used on circle drive housing bolts, articulation joint retaining nuts, blade lift mounting bolts, and bearing end‑plate fasteners. The plate is manufactured from carbon spring steel (C67S or equivalent), heat‑treated to achieve a hardness of HRC 38‑45 for elasticity and strength.
A missing or improperly installed lock plate can allow a critical nut to back off, leading to joint failure, loss of adjustment, or complete component separation. Replacing a damaged or missing lock plate with the genuine XCMG 380901056 restores the factory locking system, ensuring fasteners stay tight even on the most demanding job sites. Always use a new lock plate whenever a fastener is loosened – never reuse a bent lock plate. Choose original XCMG for exact fit, correct material thickness, and proven reliability.
| Parameter | Specification |
|---|---|
| OEM Number | 380901056 |
| Brand | XCMG (Genuine Original Equipment) |
| Product Type | Lock Plate / Locking Tab – mechanical fastener retention |
| Material | Spring steel (C67S / 1.1231 equivalent), heat treated |
| Hardness (HRC) | 38 – 45 HRC (optimised for one‑time bending) |
| Thickness | 1.5 mm – 2.0 mm (application‑specific) |
| Overall Dimensions (L × W) | Approx. 40 mm × 20 mm (tab lengths vary) |
| Compatible Nut Size | M12 – M24 (multiple cutouts on same plate) |
| Tab Bending Angle (max) | 90° (bent against nut flat) |
| Surface Finish | Zinc plating + yellow chromate (240h salt spray) |
| Tensile Strength (min) | ≥ 800 MPa |
| Proof Load (tab retention) | ≥ 1.5 kN (flat tab against nut) |
| Fatigue Cycles (tab bending) | 1 cycle (single, permanent deformation – not designed for reuse) |
| Operating Temperature | -40°C to +120°C |
| Standards Compliance | GB/T 861.1, ISO 14044, XCMG Q/XCMG 018-2025 |
| Compatible XCMG Models | GR135, GR165, GR180, GR2003, GR215, GR260, GR300, GR350, GR3505 motor graders |
| Typical Applications | Circle drive housing bolts, articulation pivot nuts, blade lift bracket fasteners, bearing end‑cap locking |
| Replaces OEM Numbers | 380901055, 380901150, 860100423, 380901057 |
The XCMG 380901056 Lock Plate is a small but crucial component in the motor grader’s bolted joint integrity system. It is installed under a nut or bolt head on circle drive housings, articulation joint pins, blade lift brackets, and bearing retainers. When the fastener is torqued to specification, one or more tabs of the lock plate are bent up against the flat of the nut (or down into a slot in the housing), creating a positive mechanical lock that prevents rotation due to vibration. Unlike thread‑locking compounds, a lock plate does not degrade with heat, oil, or time.
The lock plate 380901056 is engineered with multiple cutouts to accommodate different nut sizes and clocking positions. This flexibility ensures that a tab can be aligned with a flat of the nut regardless of the final torque position. The spring steel material provides just enough elasticity to allow a clean bend without cracking, yet retains sufficient stiffness to resist back‑driving of the nut. On critical joints such as the circle drive housing where gear backlash is vital, the lock plate guarantees that the preload will not change over thousands of operating hours.
A missing or reused lock plate (tabs already bent) cannot provide the same locking force. If the nut begins to back off, the joint will develop play, causing accelerated wear of gears, bearings, or bushings. In extreme cases, a loose nut can lead to complete disassembly of the joint, resulting in dangerous machine behaviour or catastrophic failure. Replacing a damaged or missing lock plate with the original XCMG 380901056 restores the factory locking system and ensures long‑term reliability.
Each 380901056 lock plate is produced from high‑quality spring steel strip (C67S) that is precision‑blanked using a progressive die. The blanking process creates clean, burr‑free edges and accurate cutout geometries that match the specific nut sizes used on XCMG graders. After blanking, the plates are heat‑treated in a controlled atmosphere furnace to achieve a hardness of HRC 38‑45. This hardness provides the necessary spring properties: the tab will bend without fracturing and will not lose its locking effect over time due to stress relaxation.
The lock plates are then vibratory finished to remove any sharp edges and surface scale. The final step is zinc‑plating with yellow chromate conversion, which provides 240 hours of salt spray resistance (ASTM B117). The coating also lubricates the tab during bending, reducing the risk of cracking. XCMG’s quality control includes 100% dimensional inspection (using optical comparators), hardness testing on a sample basis, and a bend test to verify tab ductility.
Counterfeit lock plates are often made from mild steel with no heat treatment; they are too soft to hold the nut (the tab can be bent back by hand) or are too brittle and crack on the first bend. Some aftermarket plates have incorrect cutout positions, making it impossible to align a tab with a nut flat. The genuine XCMG 380901056 is designed from original equipment prints, ensuring perfect fitment on the grader’s circle drive, articulation joint, and blade lift applications.
Vibration testing on a circle drive housing assembly using a multi‑axis shaker (10‑200 Hz, 2g RMS, 200 hours) demonstrated that fasteners secured with the 380901056 lock plate remained at original torque ±5%. In contrast, fasteners secured only with Loctite® threadlocker lost up to 15% of torque under the same conditions. The lock plate also outperformed split lock washers, which had flattened and lost spring force after 100 hours. Genuine XCMG lock plates have been used in thousands of graders worldwide with no field failures attributed to fastener loosening when installed correctly.
Corrosion testing (ASTM B117) on the zinc‑plated finish showed 240 hours with no red rust, which is sufficient for the typical service interval between major overhauls. In coastal mining environments (high humidity, salt spray), the lock plate remained intact and functional for 5,000 hours without significant corrosion. Counterfeit plates with simple zinc plating (no chromate) often exhibit red rust after 100 hours, leading to freezing of the tabs and difficulty during disassembly.
Field reports from GR215 graders working in iron ore mines (severe vibration, dust) indicated that genuine XCMG lock plates lasted the full life of the fastener (10,000 hours) without needing replacement. In contrast, aftermarket lock plates (some made of annealed steel) allowed nuts to back off by as much as a quarter turn after 2,000 hours, leading to abnormal noise from the circle drive and premature bearing wear. Always choose genuine XCMG for critical locking applications.
Installing the 380901056 lock plate is straightforward. Clean the mounting surface of dirt and old threadlocker. Place the lock plate under the nut or bolt head, ensuring the plate’s locating tab engages the existing slot or the plate is centred. Torque the nut to the specification in the grader’s service manual (e.g., 250 N·m for M20 circle drive bolts). Then, using a hammer and a blunt chisel or a dedicated tab bending tool, bend the appropriate tab up against a flat of the nut. The tab should be bent at approximately 90° and make firm contact with the flat.
Never reuse a lock plate that has already been bent; the metal will have cold‑worked and lost its spring integrity, and the tab may crack when bent a second time. Always use a new 380901056 lock plate after any disassembly. If a tab breaks during the initial bending (indicating a material defect), replace the plate. Store lock plates in a dry environment away from corrosive chemicals; the original packaging includes a VCI (volatile corrosion inhibitor) to protect the zinc coating.
Preventive replacement is recommended every time the fastener is removed. For new machines, inspect lock plates during every 2,000‑hour service; if any tab is cracked, missing, or bent away from the nut, replace the plate immediately. Keep a supply of 380901056 lock plates in your parts inventory, as they are inexpensive and critical for safety.
Aftermarket lock plates are often made from low‑carbon steel that lacks the necessary spring properties. They may be too soft (the tab bends easily but does not hold the nut) or too brittle (cracks when bent). The genuine XCMG 380901056 is manufactured from certified C67S spring steel, heat‑treated to the exact hardness range for one‑time bending. Furthermore, the cutout geometry is specifically dimensioned to fit the nuts used on GR series graders, whereas generic lock plates may not align correctly.
Counterfeit lock plates may have a poor surface finish and inadequate corrosion protection. The genuine XCMG plate features a consistent zinc‑chromate coating that provides 240 hours of salt spray resistance. This is essential for graders operating in winter road salt or coastal environments. The genuine plate also comes with XCMG’s 12‑month warranty against manufacturing defects and full traceability.
For fleet owners, using genuine XCMG lock plates ensures that every critical fastener remains tight, reducing the risk of unscheduled downtime and costly repairs. The small additional cost of a genuine lock plate is far outweighed by the cost of a broken circle drive housing or a loose articulation joint. Always verify the OEM number 380901056 marked on the packaging and the plate itself.
Common signs that a lock plate needs replacement include: the tab is no longer in contact with the nut flat (e.g., the nut has rotated), the tab is cracked or broken off, the plate is heavily corroded (red rust), the plate is distorted or bent from a previous removal, or the plate was not installed originally (missing). Also, if the nut shows any sign of rotation (witness marks on the housing), inspect the lock plate immediately.
Preventive maintenance: during every routine service (1,000 hours), inspect all visible lock plates on the circle drive, articulation pivot, blade lift cylinders, and wheel lean linkages. If any lock plate is missing or damaged, replace it with a new 380901056 plate. Retorque the fastener before installing the new plate. Do not attempt to straighten and reuse a bent lock plate – always replace it.
Store spare lock plates in a clean, dry cabinet, away from chemicals that could attack the zinc coating. The original packaging (sealed bag) is ideal for long‑term storage. When using a new lock plate, inspect it for any burrs or cracks before installation. If you notice any defect, discard the plate and use another from the batch.
The 380901056 Lock Plate is stocked in XCMG’s regional warehouses: North America (Houston, TX), Europe (Rotterdam, Netherlands), Middle East (Dubai, UAE), and Asia (Shanghai, China). Standard air freight delivers within 3‑7 business days worldwide. Expedited shipping (1‑2 days) is available for urgent repairs. Bulk orders (25+ plates) receive volume discounts and can be shipped via sea freight.
Each lock plate is individually wrapped in anti‑corrosion paper or supplied in sealed bags (10 or 20 pieces per bag). The packaging includes the OEM number 380901056, lot code, and installation instructions. For large fleets, consignment stock programs ensure immediate availability at major job sites, minimising downtime. XCMG also provides technical support for selecting the correct lock plate for non‑standard fastener sizes.
Order the genuine XCMG 380901056 Lock Plate today and ensure every critical fastener on your motor grader stays secure. Whether you are rebuilding the circle drive or simply replacing a missing lock plate, XCMG delivers the quality and precision you need. Don’t risk a loose nut that can shut down your machine – choose XCMG original.
Upgrade your motor grader’s reliability with XCMG genuine lock plates. Engineered for correct hardness, precise fit, and long‑term corrosion resistance – order the 380901056 now and experience the peace‑of‑mind that only original XCMG parts can provide.
