Anti Loosening Slotted Round Lock Nuts For Shafts
I. Product Definition
Slotted round nuts (compliant with standards like GB/T 812, DIN 981, or IFI 167) feature radial slots on their side. They work with lock washers or cotter pins to achieve anti-loosening locking and axial positioning for shaft-mounted components. Widely used in precision machinery, construction equipment, and automotive systems.
II. Structure & Anti-Loosening Principle
- Shape: Circular outer profile with internal threads matching the shaft’s threaded end. 4–6 radial slots are evenly cut into the side.
- Anti-Loosening Logic:
After tightening the nut to the designed torque, lock washer tabs fit into the slots, or cotter pins pass through the slots and shaft pin holes. This locks the nut’s rotational freedom, preventing loosening under vibration, impact, or cyclic loads.
III. Materials & Performance
| Material Type |
Performance Highlights |
Typical Applications |
| Carbon Steel (45#, 40Cr) |
High strength; quenched (HRC 35–40 for hardness). |
Heavy-duty equipment (rolling mills, excavators). |
| Stainless Steel (304, 316) |
Corrosion resistance; lightweight. |
Food machinery, marine engineering. |
| Alloy Structural Steel |
High-temperature resistance (≤400℃); fatigue resistance. |
Aero-engines, high-temperature furnaces. |
Surface Treatments (For Harsh Environments):
- Galvanized: Basic corrosion protection (salt spray resistance: ~500 hours).
- Black Oxide: Enhanced wear resistance; ideal for low-corrosion scenarios.
- Dacromet: Superior corrosion resistance (salt spray life ＞1,000 hours); suits humid/coastal environments.
IV. Core Applications
- Precision Machinery: Secures bearing inner rings on machine tool spindles (e.g., machining centers, grinders) to maintain rotational accuracy.
- Construction Machinery: Used on excavator bucket pins, loader drive shafts, and hydraulic cylinders—resisting heavy impact and vibration.
- Automotive Industry: Fixes axle hubs, transmission input shafts, and wheel bearings—ensuring maintenance-free anti-loosening.
- Agricultural Equipment: Secures tractor PTO shafts, plow connections, and harvester components—withstanding dust, moisture, and heavy loads.
V. Installation & Selection Guidelines
- Installation Steps:
Screw the nut onto the shaft end and pre-tighten to the designed torque.
Align lock washer tabs with the slots, then bend the tabs to fit the shaft shoulder (or insert cotter pins through slots and shaft holes).
Inspect the fit clearance between slots and washers/pins to ensure no play.
- Selection Parameters:
Thread Size: M10 to M100 (matches the shaft’s threaded end).
Number of Slots: 4 or 6 slots (matches the number of lock washer tabs).
Surface Treatment: Choose galvanized, black oxide, or dacromet based on environmental corrosion levels.
VI. Core Advantages
Reliable Anti-Loosening: Mechanical locking (via washers/pins) outperforms nylon nuts in high-vibration environments.
Precise Axial Positioning: Works with shaft shoulders to fix bearings, gears, or pulleys—simplifying shaft system design.
High Standardization: Compatible with GB, DIN, and IFI standards—ensuring interchangeability for global equipment.
Versatile Material Options: Carbon, stainless, and alloy steels cover applications from civilian machinery to military-grade systems.
Note: The nuts in the images are side-slotted round nuts (matching lock washers). Specific specifications depend on thread diameter, slot width, and the number of slots.
