High-Performance Locking Nut & Inner Head Nut for Cone Crushers

Metso HP Series Main Frame Lock Bolt & Fasteners (OEM N41060200 / 7041068006)

The Main Frame Lock Bolt is a safety-critical fastener engineered for Metso Nordberg HP series cone crushers (HP100 through HP500).
Working in tandem with the Main Frame Pin assembly, these high-tensile bolts secure the adjustment ring to the crusher’s mainframe, preventing rotational slippage and maintaining structural alignment under extreme vibrational loads.

Unlike standard Grade 8.8 commercial hardware, our crusher spares are manufactured to Grade 10.9 or 12.9 specifications.
They are designed to withstand the cyclic tension and shear forces generated during the crushing of hard granite and iron ore, ensuring your machine’s geometry remains rigid for consistent product gradation.

Core Engineering Advantages

We supply precision-forged fasteners that meet the strict metallurgical requirements of OEM Metso specifications.

• High-Strength Metallurgy: Forged from 42CrMo4 (AISI 4140) Alloy Steel.
  Through Quenching and Tempering (Q&T), we achieve a tensile strength of ≥1040 MPa, providing exceptional resistance to fatigue fracture.
• Anti-Vibration Thread Design: Threads are rolled (not cut) after heat treatment to increase fatigue life.
  Precision tolerance (6g) ensures a tight engagement with the mainframe threads, preventing loosening due to high-frequency crusher vibration.
• Corrosion Protection: Available with Dacromet® coating or Manganese Phosphate finish to prevent thread seizing (galling) caused by rust and dust ingress, facilitating easier removal during maintenance.

Technical Specifications

The following parameters define the performance capability of our premium locking bolts, ensuring full interchangeability with original parts.

Field Diagnostic Tips: When to Replace?

Even high-quality wear parts and fasteners have a service life.
Visual inspection alone is not enough. Use these diagnostic steps to determine if your lock bolts require replacement:

• Check for “Necking”: Inspect the unthreaded shank portion of the bolt.
  If it appears thinner than the original diameter, the bolt has undergone plastic deformation (yielded) and lost its clamping force. Replace immediately.
• Thread Pitch Elongation: If a new nut does not spin freely by hand over the threads where the clamping load was applied, the thread pitch has stretched.
  The bolt is compromised and must be scrapped.
• Corrosion Pitting: Deep pits can act as stress risers, leading to sudden brittle fracture.
  Replace bolts showing significant pitting beyond surface rust.

Expert Note on Installation

Maximizing Service Life: Never reuse a plastically deformed bolt.
When installing new Main Frame Lock Bolts, ensure the mating surfaces on the adjustment ring are free of debris.
Apply a Molybdenum Disulfide (MoS2) based anti-seize compound to the threads and under the bolt head to ensure the applied torque translates into true clamping force (preload) rather than overcoming friction.

Don’t risk structural failure. Contact our engineering team today to verify the correct Locking Bolt Part Number for your specific HP model.