Screw Gear (Crossed Helical)

Understanding Screw Gears (Crossed Helical Gears)

Screw gears are essentially helical gears used in pairs to connect shafts that are not parallel and do not intersect (skew axes). Their meshing action is different from parallel-axis helical gears:

• Skew Axis Operation: Their primary function is to transmit motion between shafts oriented at an angle in different planes. The most common angle is 90 degrees.
• Point Contact & Sliding: Unlike the line contact in parallel helical gears, screw gears mesh with high sliding at a theoretical point of contact. This limits their load-carrying capacity and efficiency.
• Helix Angle & Hand: The sum or difference of the helix angles determines the shaft angle. For a common 90-degree shaft angle, both gears must have the same hand (either both right-hand or both left-hand).
• Ratio Determination: The gear ratio is determined by the ratio of the number of teeth, similar to other gear types.

Advantages:

• Simple Skew Axis Drive: Provides a straightforward mechanical method for connecting non-intersecting, non-parallel shafts.
• Potentially Quiet Operation: The helical form can contribute to relatively smooth operation at lower loads.

Considerations:

• Low Load Capacity: Point contact results in high stress, limiting use to light loads.
• Lower Efficiency: Significant sliding friction leads to lower efficiency compared to spur, parallel helical, or bevel gears.
• Wear Potential: High sliding necessitates careful material selection and lubrication to manage wear. Often, dissimilar materials (e.g., steel and bronze/plastic) are used.
• Thrust Loads: Like helical gears, they generate axial thrust forces.

Shreeji Gears: Your Ahmedabad Source for Screw Gears

Shreeji Gears applies its precision manufacturing capabilities to produce reliable screw gear sets for specific light-duty, skew-axis applications.

Why Choose Shreeji Gears for Screw Gears?

• Material Selection Guidance: Advising on appropriate material combinations (e.g., hardened steel paired with bronze or engineered plastics) or suitable alloy steels based on load, speed, and life requirements to mitigate wear in these helical-gear-pair types.
• Precision Helical Cutting: Utilizing accurate gear hobbing or shaping processes to generate the required helix angles and tooth profiles.
• Matched Pairs: Manufacturing screw gears as matched sets to ensure proper meshing and performance for the intended non-intersecting-shaft configuration.
• Quality Control: Inspecting critical parameters like helix angle, lead accuracy, tooth profile, and center distance compatibility.
• Application Suitability: Ideal for light-duty drives, instrumentation, feed mechanisms, timers, and other mechanisms where transmitting motion between skew shafts is the primary goal.
• Customization: Producing custom-screw-gear sets based on shaft angle, desired ratio, center distance, materials, and mounting needs.

General Technical Specifications (Customizable):

• Gear Type: Screw Gears / Crossed Helical Gears
• Shaft Orientation: Non-Intersecting, Non-Parallel (Skew)
• Shaft Angle: Typically 90 degrees, other angles possible.
• Hand (for 90°): Matched sets (Both RH or Both LH)
• Material: Alloy Steels (e.g., EN8, EN24, EN353), Bronze, Cast Iron, Engineered Plastics, often used in dissimilar pairs (e.g., Steel/Bronze).
• Module Range / DP: Available across a range suitable for light-duty applications (Contact us).
• Quality Standards: Manufactured to relevant industry practices for accuracy.
• Pairing: Supplied as matched sets only.

Need to transmit motion between skew shafts for a light-duty application? Consult Shreeji Gears, your experienced screw gear manufacturer in Ahmedabad. Contact us today to discuss your crossed helical gear requirements!