Internal / External Splined Gear & Splined Shaft Extremely High Load Capacity Excellent Alignment

Internal/External Splined Gear & Splined Shaft Extremely High Load Capacity Excellent Alignment

Part 1: Spline Connection Overview

A spline connection is a connection formed by machining multiple uniformly distributed key teeth on a shaft and in a hub. It is equivalent to a combination of multiple parallel keys. The splines on a gear or shaft are divided into external splines (machined on the external surface of a shaft) and internal splines (machined on the internal surface of a hole).

Part 2: External Splined Gear/Shaft & Internal Splined Gear

1. Introduction

• External Splined Gear/Shaft: Refers to a gear or shaft with spline teeth machined on its external cylindrical surface. It typically acts as an input or output shaft, mating with a component having internal splines (e.g., a coupling, another gear).

• Internal Splined Gear: Refers to a gear with spline teeth machined on its internal bore surface. It is usually used to mate with an external splined shaft, capable of transmitting torque while also allowing axial sliding for functions like speed change or movement.

2. Advantages (Compared to single key connections)

• Extremely High Load Capacity: Multiple teeth are in contact simultaneously, providing a load capacity far superior to single key connections, enabling the transmission of enormous torque and power.

• Excellent Alignment: Involute spline profiles offer good self-centering capability, ensuring concentricity between the shaft and hub, and providing high transmission accuracy.

• Good Guidance: Particularly suitable for applications where gears need to slide frequently on the shaft (e.g., gearbox shifting), allowing for smooth movement.

• High Reliability: Lower stress concentration, higher fatigue strength, more reliable connection, and longer service life.

• Compact Structure: For transmitting the same torque, a splined connection is generally more compact and lighter than a keyed connection.

3. Key Technical Parameters

• Number of Teeth: The number of spline teeth.

• Module: The fundamental parameter determining the size of the spline teeth.

• Pressure Angle: Common ones are 30°, 37.5°, 45° (for square splines), or 20°, 30° (for involute splines). Involute splines are more widely used.

• Major Diameter, Minor Diameter, Pitch Diameter: Key diameter dimensions of the spline.

• Fit Type: Categorized into sliding fit (for axial movement) and fixed fit (for permanent connections), achieved by varying the tolerance bands for space width and tooth thickness.

• Accuracy Grade: Rated according to ISO, ANSI, or DIN standards, affecting the tightness of fit and smoothness of transmission.

4. Applications
Spline connections are widely used in applications requiring high torque transmission, excellent alignment, and the need for relative sliding:

• Automotive Transmissions: Synchronizer assemblies, connection between gears and shafts (the most classic application).

• Machine Tools: Spindle drive systems of milling machines, lathes.

• Aircraft Engines: Connections between rotors and disks.

• Heavy Machinery: Drive shafts for excavators, cranes.

• 4WD Systems: Connections between propeller shafts and differentials, transfer cases.

External internal spline shaft

High Load internal spline gear

External Splined Gear Shaft

Internal / External Splined Gear & Splined Shaft Extremely High Load Capacity Excellent Alignment Images