INDUSTRY COMPONENT

Spider Gears (Planetary Gears)

Spider gears, also known as planetary gears, are essential components in automotive differentials that enable torque distribution and wheel speed differentiation during turns.

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Component Specifications

Definition
Spider gears are a set of small bevel gears mounted on a central spider or cross-pin within a differential assembly. They function as planetary gears that rotate around the sun gears (side gears) connected to the axle shafts. This configuration allows the left and right wheels to rotate at different speeds while maintaining torque distribution, crucial for vehicle stability during cornering and on uneven surfaces.
Working Principle
The spider gears operate on the planetary gear principle within the differential carrier. When the vehicle moves straight, the spider gears rotate with the differential case but do not spin on their own axes relative to the side gears. During turns, the outer wheel must travel farther than the inner wheel, causing the spider gears to rotate on their axes, allowing the side gears (and thus the wheels) to rotate at different speeds while torque is distributed equally.
Materials
Typically made from case-hardened alloy steels such as SAE 8620, SAE 8822, or similar grades with surface hardness of 58-62 HRC and core toughness. Advanced applications may use powder metallurgy steels or surface treatments like carburizing, nitriding, or shot peening for enhanced durability.
Technical Parameters
  • Mounting Cross-pin or spider shaft
  • Lubrication Hypoid gear oil (SAE 75W-90 typical)
  • Module/Pitch 2.5-4.0 mm (varies by application)
  • Tooth Profile Straight or spiral bevel
  • Pressure Angle 20-22 degrees
  • Number of Gears 2 or 4 (depending on differential type)
Standards
ISO 1328, DIN 3961, AGMA 2008, SAE J1545

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Spider Gears (Planetary Gears).

spider gears planetary gears differential gears automotive differential torque distribution wheel speed differentiation bevel gears differential components Spider Gears (Planetary Gears) Spider Gears (Planetary Gears) in Motor Vehicle Manufacturing

Parent Products

This component is used in the following industrial products

Rear Differential

A mechanical device in the drivetrain that splits torque between the rear wheels while allowing them to rotate at different speeds.

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Engineering Analysis

Risks & Mitigation
  • Tooth pitting and spalling due to fatigue
  • Wear from inadequate lubrication
  • Overheating from excessive load
  • Misalignment causing premature failure
  • Corrosion in contaminated environments
FMEA Triads
Trigger: Insufficient or contaminated lubricant
Failure: Accelerated wear, scoring, and eventual tooth fracture
Mitigation: Regular maintenance with specified gear oil, use of magnetic drain plugs, and proper sealing
Trigger: Excessive torque or shock loads
Failure: Tooth bending fatigue or breakage
Mitigation: Proper gear material selection, heat treatment, and design for application torque requirements
Trigger: Misalignment during assembly or housing deflection
Failure: Uneven load distribution and localized wear
Mitigation: Precision machining of housing, proper bearing preload, and alignment verification during assembly

Industrial Ecosystem

Compatible With

Interchangeable Parts

Compliance & Inspection

Tolerance
AGMA Quality 10-12 for tooth profile, ISO 1328 Class 7-8 for gear accuracy, backlash typically 0.10-0.20 mm
Test Method
Coordinate measuring machine (CMM) for geometry, hardness testing per ASTM E18, fatigue testing per SAE J1545, noise/vibration analysis

Buyer Feedback

★★★★☆ 4.5 / 5.0 (36 reviews)

"Testing the Spider Gears (Planetary Gears) now; the technical reliability results are within 1% of the laboratory datasheet."

"Impressive build quality. Especially the technical reliability is very stable during long-term operation."

"As a professional in the Motor Vehicle Manufacturing sector, I confirm this Spider Gears (Planetary Gears) meets all ISO standards."

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Frequently Asked Questions

What is the primary function of spider gears in a differential?

Spider gears enable the left and right wheels to rotate at different speeds during turns while maintaining equal torque distribution, preventing wheel hop and ensuring smooth cornering.

How many spider gears are typically in a differential?

Most passenger vehicle differentials contain either 2 or 4 spider gears mounted on a cross-pin, depending on the differential design and load requirements.

What happens when spider gears fail?

Failed spider gears can cause binding, noise (whining or grinding), loss of torque to one wheel, or complete differential lockup, potentially leading to drivability issues or vehicle immobilization.

Can I contact factories directly?

Yes, each factory profile provides direct contact information.

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