Jaw Crusher Eccentric Shaft ISO 9001:2015 SSAB Hardox Authorized

Jaw Crusher Eccentric Shaft

Eccentric Drive Shaft for Jaw Crushers — Drives Pitman Toggle Plate Motion — 42CrMo / 40CrNiMo / 45# Steel — Forged Alloy Steel / Hot Rolled Steel

Material Alloy Structural Steel (42CrMo / 40CrNiMo), Carbon Steel (45# / 40Cr), Forged or Hot Rolled

Hardness HB 220-280 (Normalizing) / HB 260-320 (Q+T) / HRC 28-35 Surface — High Fatigue Resistance

Compatibility Metso C Series / Sandvik CJ Series / Shanbao PE/PEX Series / Hongji / Parker / Kue-Ken

Certification ISO 9001:2015 Certified, Full Material Test Report, UT/MT NDT Certificate, Dynamic Balance G2.5

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Jaw Crusher Eccentric Shaft — Material Specifications | ZHILI

Grade	Material	Yield (MPa)	Tensile (MPa)	Hardness	Application
40Cr	Cr0.8-1.1% + C0.37-0.44%	785	980	28-32 HRC	PE150x250 to PE400x600
42CrMo	Cr0.9-1.2% + Mo0.15-0.25%	930	1080	30-35 HRC	PE500x750 to PE900x1200
35CrMo	Cr0.8-1.1% + Mo0.15-0.25%	835	980	28-32 HRC	Medium duty, fatigue resist
40CrNiMo	Cr-Ni-Mo Alloy	890	1050	30-35 HRC	Heavy duty, impact load
34CrNiMo6	Ni-Cr-Mo Alloy	900	1100	32-36 HRC	Extreme duty, large jaw
18CrNiMo7-6	Case Hardening Steel	850	1150	58-64 HRC (Surface)	High wear bearing seats

Process	Parameter	Result	Feature
Forging	Open die, 3:1 ratio	Fiber flow aligned	Max fatigue resistance
Normalizing	850-880 C, air cool	220-250 HB	Refine grain structure
Quenching	840-860 C, oil/polymer	50-55 HRC	Through-hardened core
Tempering	550-650 C, 2-4 hrs	28-35 HRC	Toughness + strength
Induction HF	Bearing seats only	55-60 HRC local	Wear resistance
Finish Grind	Ra 0.8-1.6	Precision fit	Bearing life +200%

Jaw Model	Shaft Dia. (mm)	Length (mm)	Eccentric (mm)	Weight (kg)	Material
PE150x250	90	450	12	25	40Cr
PE250x400	120	600	15	55	40Cr
PE400x600	170	850	20	140	40Cr / 42CrMo
PE500x750	200	1,000	25	220	42CrMo
PE600x900	230	1,150	30	340	42CrMo
PE750x1060	260	1,300	35	480	42CrMo
PE900x1200	300	1,500	40	720	42CrMo / 40CrNiMo
PE1200x1500	360	1,800	50	1,250	40CrNiMo / 34CrNiMo6
PE1500x1800	420	2,100	60	1,950	34CrNiMo6

Selection Quick Reference

Small jaw crushers (PE150x250 to PE400x600, feed <400 mm): 40Cr forged eccentric shaft — sufficient strength for small crushing forces (<150 kN toggle load), cost-effective standard material, 28-32 HRC tempered for balanced toughness
Medium jaw crushers (PE500x750 to PE900x1200, feed 500-800 mm): 42CrMo forged shaft — Cr-Mo alloying provides fatigue resistance for cyclic loading (500-1,200 crushing strokes/min), critical for continuous duty quarry operations
Large jaw crushers (PE1200x1500+, feed >1,000 mm): 40CrNiMo or 34CrNiMo6 — Ni-Cr-Mo alloy mandatory for massive crushing forces (toggle load >3,000 kN), impact resistance from large boulder feed, 32-36 HRC for maximum load capacity
Critical surface finish: Bearing journal surfaces ground to Ra 0.8-1.6 micrometers — rougher surfaces reduce bearing life 40-60%. Induction hardening of bearing seats to 55-60 HRC extends bearing service life 200%+ in dusty environments
Quality assurance: 100% ultrasonic testing (UT) for internal defects, magnetic particle inspection (MT) for surface cracks. Bending tolerance <0.05 mm/m -- any bend causes vibration and bearing failure within 500 operating hours

Certifications & Authorizations

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National Invention Patent Certificate — Multi-hammer Sand Mold Casting Process — Luoyang Zhili ZL 2016 1 0056588.5

ISO 9001:2015 Quality Management System Certificate — Luoyang Zhili New Materials — GICG UK Certified IAF Accredited Valid until 2027

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Jaw Crusher Eccentric Shaft — FAQ | ZHILI

01 How do I tell if my eccentric shaft is failing, and when should I replace it? +

Eccentric shaft failure begins with warning signs detectable weeks before catastrophic breakage. Ignoring early indicators leads to bearing seizure and frame damage:

Early Warning

Warm Bearings

Moderate Damage

Noise + Vibration

Critical

Crack Indication

Replace Threshold

Any Crack Detected

Stage 1 — Early (bearing temperature rise): Normal operating temp 55-70 C. Sustained temperature above 85 C indicates shaft deflection or misalignment. Check bearing lubrication first, but if temperature remains high after relubrication, the shaft is likely developing micro-cracks at the eccentric journal transition radius.
Stage 2 — Moderate (audible noise + vibration): A rhythmic thumping sound at each crank revolution indicates eccentricity change — a fatigue crack is growing. Vibration readings >7 mm/s RMS require immediate scheduled inspection. Operating beyond 15 mm/s risks bearing cage collapse.
Stage 3 — Critical (visible crack): A hairline crack at the eccentric journal radius (transition from main shaft body to offset) is the most common failure point. Replace immediately — do not attempt weld repair. Welding creates heat-affected zones that fail within 50-200 operating hours.

Inspection rule: Perform magnetic particle inspection (MT) on the journal radius and keyway root every 2,000 operating hours. The keyway is a stress concentrator — 60% of shaft failures initiate at the keyway corner. Replace the shaft at the first sign of any surface crack — fatigue crack propagation in 42CrMo steel accelerates from 0.01 mm/cycle to 0.1 mm/cycle within 500,000 cycles.

02 Why does my eccentric shaft keep breaking at the bearing journal, and how can I prevent it? +

The bearing journal radius is the highest stress concentration point on the shaft. Failure is almost always due to incorrect installation or operation:

Root Cause #1

Bearing Misalignment

Root Cause #2

Over-tightening

Root Cause #3

Undersized Radius

Prevention

Precision Fit + Torque

Bearing misalignment (40% of failures): Bearing inner ring must sit flush against the shaft shoulder. Even 0.05 mm of angular misalignment concentrates bending stress at the radius. Use induction heating or oil bath to expand bearings to 110-120 C for hot mounting — never hammer bearings onto a cold shaft.
Over-tightening the bearing lock nut (25% of failures): The lock nut creates axial preload. Excessive torque compresses the bearing inner ring onto the shaft, reducing the bearing’s internal radial clearance. The shaft then transmits bending loads directly to the bearing, concentrating stress at the journal radius. Use the manufacturer’s torque specification — typically 250-400 Nm for M100-M120 nuts.
Undersized journal fillet radius (20% of failures): The transition between journal and shaft body must have a minimum fillet radius of 4-6 mm. A sharp corner (R<2 mm) reduces fatigue life by 60-80%. Inspect the radius with a radius gauge during installation — do not accept a shaft with a tool mark or machining groove at this critical point.
Material selection matters: For jaw crushers above PE600x900, specify 42CrMo minimum. 40Cr shafts in medium-duty crushers show a 3x higher failure rate when processing hard rock with intermittent tramp metal.

Installation sequence: (1) Heat bearing to 110-120 C, (2) Slide onto shaft until flush against shoulder — no gap allowed, (3) Allow to cool to ambient before torquing lock nut, (4) Torque to spec using calibrated wrench, (5) Check runout with dial indicator — must be <0.03 mm TIR at both bearing journals. Any deviation above 0.05 mm requires disassembly and recheck.

03 What is the difference between forged and cast eccentric shafts, and which is more reliable? +

Forged shafts are mandatory for jaw crushers. Cast eccentric shafts are not recommended due to fatigue vulnerability:

Forged Fatigue Life

10-20M cycles

Cast Fatigue Life

2-5M cycles

Forged Grain Flow

Aligned

Cast Internal Defects

Porosity Risk

Forged shaft advantages: The forging process aligns the steel grain (fiber) flow along the shaft’s longitudinal axis and around the eccentric offset. This continuous grain structure provides 3-5x the fatigue life of a cast shaft with equivalent chemistry. All ZHILI eccentric shafts are 100% forged — we never supply cast shafts.
Cast shaft disadvantages: Even with advanced NDT (UT, radiographic), cast shafts contain micro-porosity that acts as crack initiation sites under cyclic loading. A jaw crusher at 275 RPM experiences ~144 million fully-reversed bending cycles per year. A single 0.5mm casting defect can propagate to failure within 2-3 months of operation.
How to verify forged vs. cast: Check for a forging reduction ratio stamp (typically 3:1 minimum). Inspect the machined surface for dendritic grain patterns (cast) vs. smooth uniform appearance (forged). Request the material certificate (EN 10204 3.1) — forging origin is documented in the production route.
The only exception: Very small laboratory jaw crushers (5 tph), forged is the only acceptable specification.