Symons Cone Crusher Head Assembly | 4.25ft – 7ft OEM Parts

Symons Cone Crusher Head & Shaft Assembly – OEM Replacement Spares

The Symons Cone Assembly (Head & Shaft) is the central moving component for classic Symons-style crushers (3ft, 4ft, 4.25ft, 5.1/2ft, and 7ft Standard/Short Head).
This assembly dictates the crushing geometry and transmits the gyratory force.
Unlike simple wear parts, this is a complex mechanical assembly comprising the Main Shaft, Head Center (Cone), and usually the installed Spherical Seat.

As a dedicated crusher parts supplier, we engineer these assemblies to address the common fatigue points found in original Nordberg Symons designs.
Our assemblies are fully interchangeable with OEM specifications, offering a cost-effective solution for restoring your vintage equipment to full operational capacity.

Core Engineering & Manufacturing Advantages

We utilize modern metallurgy to upgrade legacy designs, ensuring the assembly withstands the high-torque demands of modern aggregate production.

• Main Shaft Integrity: Forged from 42CrMo4 (AISI 4140) or 18CrNiMo7-6 alloy steel.
  We apply a Multi-Stage Heat Treatment (Quenching & Tempering) to achieve high tensile strength (>850 MPa), preventing shaft snapping near the thread or head seating area.
• Head Center Structure: The Head is cast from ASTM A148 Grade 90-60 Cast Steel (Not Manganese).
  It is annealed to relieve stress, ensuring it retains its spherical geometry under the crushing load.
  Note: The Mn18Cr2 Mantle is installed over this structural head.
• Precision Machining: The spherical seating surface is CNC machined and polished to Ra 0.8.
  This mirror finish is critical for maintaining the hydrodynamic oil wedge with the socket liner, preventing “Head Spin.”
• Interference Fit: The Main Shaft is cryogenically fitted (using liquid nitrogen) into the Head Center to ensure a permanent bond that will not loosen under vibration.

Technical Specifications: Compatible Models

The following table outlines the operational parameters for the machines our Head & Shaft assemblies are designed to fit.
Please verify your specific model (Standard vs. Short Head) before ordering crusher spares.

Performance Optimization & Info Gain

Upgrading your Head Assembly affects more than just reliability; it stabilizes your product output.

• Restored Nip Angle: A worn Head Center can cause the mantle to sit loosely, altering the nip angle.
  New assemblies restore the correct geometry for efficient laminated crushing, reducing recirculating loads by up to 15%.
• Vibration Control: Our assemblies are dynamically balanced to G6.3 standards.
  Replacing a bent or unbalanced shaft eliminates the “wobble” that destroys socket liners and eccentric bushings.

Maintenance Diagnosis: The “Head Spin” Danger

Symons crushers are prone to “Head Spin” (the head rotating at countershaft speed when running empty).
Diagnosis Tip: If your head spins rapidly (>20 RPM) while idling, it indicates metal-to-metal contact between the Head Ball and Socket Liner.
This is often caused by a warped Head Ball on your current assembly.
If polishing the head ball doesn’t solve it, the Head Assembly requires immediate replacement to prevent a catastrophic socket failure.

Expert Note on Assembly: When installing a new Head Assembly, always replace the Socket Liner and the Eccentric Bushing simultaneously.
Mating a new precision shaft with worn bronze parts will lead to rapid point-loading and seizure.
Also, ensure the sphere is lubricated with the correct ISO viscosity oil before the first start-up.

Keep your classic Symons running like new.
Contact our engineering team today to verify shaft dimensions and request a quote for your Head Assembly.