INDUSTRY COMPONENT

Spur Gear

A spur gear is a cylindrical gear with straight teeth parallel to the axis, used for transmitting motion and power between parallel shafts in industrial machinery.

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Component Specifications

Definition
A spur gear is a fundamental mechanical component characterized by its cylindrical shape and straight-cut teeth that are oriented parallel to the gear's axis of rotation. It is designed to mesh with another spur gear on a parallel shaft to transmit rotational motion and torque efficiently. The teeth engage along a line of contact, providing smooth power transfer with minimal axial thrust. These gears are manufactured to precise geometric specifications including module/diametral pitch, pressure angle, number of teeth, and face width to ensure proper meshing and load distribution. They are critical elements in gear trains, speed reducers, and various transmission systems where parallel shaft arrangements are required.
Working Principle
Spur gears operate on the principle of conjugate action between meshing teeth profiles. As one gear (the driver) rotates, its teeth engage with the teeth of the mating gear (the driven), transmitting rotational motion and torque through direct contact. The involute tooth profile ensures constant velocity ratio and smooth engagement/disengagement. Power transmission occurs along the line of action tangent to the base circles, with forces acting radially and tangentially to create rotational motion. The gear ratio is determined by the ratio of the number of teeth on the driven gear to the number on the driver gear.
Materials
Typically manufactured from alloy steels (AISI 4140, 4340, 8620), carbon steels (1045, 4140), stainless steels (303, 304, 316), cast iron (gray, ductile), brass, bronze, or engineered plastics (nylon, acetal, polycarbonate). Heat treatment processes include carburizing, nitriding, induction hardening, or through-hardening to achieve surface hardness of 55-65 HRC for steel gears. Material selection depends on application requirements for strength, wear resistance, corrosion resistance, noise reduction, and cost.
Technical Parameters
  • Backlash 0.05 to 0.4 mm depending on precision class
  • Face Width 3 to 10 times module
  • Module Range 0.5 to 25 mm
  • Tooth Profile Involute (standard)
  • Accuracy Grade ISO 1328 Class 3 to 12, AGMA Q3 to Q15
  • Pressure Angle 20° (standard), 14.5° (historical)
  • Surface Finish 0.4 to 3.2 μm Ra
  • Diametral Pitch Range 1 to 120 DP
  • Maximum Pitch Line Velocity Up to 25 m/s for precision gears
Standards
ISO 1328, ISO 6336, AGMA 2001, AGMA 2015, DIN 3960, DIN 3990, JIS B 1702

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Spur Gear.

spur gear straight tooth gear parallel shaft gear power transmission gear train mechanical component industrial gears gear design gear manufacturing Spur Gear in Machinery and Equipment Manufacturing

Parent Products

This component is used in the following industrial products

Gear Train

A mechanical system consisting of two or more gears meshed together to transmit motion and torque between rotating shafts.

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Gear Train (Spur/Helical/Planetary)

A mechanical assembly of multiple gears that transmits and modifies torque and speed from a motor to an output shaft.

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Engineering Analysis

Risks & Mitigation
  • Tooth bending fatigue failure
  • Pitting and surface wear
  • Scoring and scuffing
  • Noise and vibration at high speeds
  • Misalignment causing uneven load distribution
  • Inadequate lubrication leading to premature failure
  • Backlash accumulation affecting precision
FMEA Triads
Trigger: Insufficient hardness or improper heat treatment
Failure: Premature tooth wear and pitting
Mitigation: Specify appropriate material grade with proper heat treatment; implement surface hardening processes; maintain adequate lubrication with correct viscosity
Trigger: Misalignment during installation or operation
Failure: Uneven load distribution leading to localized tooth breakage
Mitigation: Use precision alignment tools during installation; implement regular alignment checks; incorporate flexible couplings; design with proper tolerances and fits
Trigger: Inadequate lubrication or contamination
Failure: Scoring, scuffing, and accelerated wear
Mitigation: Establish proper lubrication schedule with recommended oil grade; implement filtration systems; use sealed gear housings; monitor oil condition regularly

Industrial Ecosystem

Compatible With

Interchangeable Parts

Compliance & Inspection

Tolerance
Tooth profile tolerance per ISO 1328 Class 5-8 for industrial applications; Runout tolerance typically 0.02-0.05 mm; Center distance tolerance ±0.05-0.2 mm depending on size and application
Test Method
Coordinate measuring machine (CMM) for geometric verification; Gear rolling test for composite error; Hardness testing (Rockwell C); Surface roughness measurement; Dye penetrant or magnetic particle inspection for crack detection; Dynamic testing under load for noise and vibration analysis

Buyer Feedback

★★★★☆ 4.6 / 5.0 (13 reviews)

"Reliable performance in harsh Machinery and Equipment Manufacturing environments. No issues with the Spur Gear so far."

"Testing the Spur Gear 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."

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Frequently Asked Questions

What are the main advantages of spur gears?

Spur gears offer high efficiency (95-99%), simple design, ease of manufacturing, cost-effectiveness, reliable performance, and ability to transmit high torque loads. They provide constant velocity ratio and are suitable for a wide range of industrial applications.

What are the limitations of spur gears?

Spur gears generate more noise at high speeds compared to helical gears, cannot transmit motion between non-parallel shafts, create only radial loads (no axial thrust), and have lower load capacity per tooth compared to some other gear types at similar sizes.

How do I select the right spur gear for my application?

Consider torque requirements, speed ratio, shaft arrangement, operating environment, space constraints, noise limitations, and service life. Calculate based on module/pitch, number of teeth, face width, material strength, and verify against bending and contact stress using ISO 6336 or AGMA standards.

Can I contact factories directly?

Yes, each factory profile provides direct contact information.

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