Knowledge

Let's systematically sort out the classification, common materials and production processes of gear shafts. Gear shafts are key mechanical parts that integrate gears and shafts in one design and manufacture, used for transmitting power and motion.

I. Classification of Gear Shafts

Gear shafts can be classified based on different dimensions:

1. Classification by structural and functional characteristics (main classification method):

- Integral gear shaft: This is the most common form, where the gear teeth part and the shaft body part are processed from a single piece of raw material. It has good structural rigidity, simple assembly, and high transmission accuracy. It is suitable for medium and small-sized gears and applications requiring high rigidity.

- Assembled/disassembled gear shaft: The gear (usually a gear ring) and the shaft body are manufactured separately and then assembled together using keys, splines, interference fits, conical surface connections, set screws, etc. It is suitable for large-sized gears (saving precious materials), situations where gears need to be replaced, or for easy maintenance.

- Combined gear shaft: It contains multiple functional parts (such as bearing journals, flanges, gears of different sizes, etc.) on the same shaft, made from one piece or welded/assembled from multiple pieces of material.

- Centering shaft/planetary carrier shaft: In planetary gear transmission, it is used to install planetary gears and serves as their rotation center.

- Drive shaft/input shaft/output shaft: Named according to their position in the transmission chain.

- Stepped shaft/straight shaft/hollow shaft: Classified based on the shape and cross-sectional features of the shaft (straight shaft has a smooth cylindrical surface, stepped shaft has different shaft diameters, and hollow shaft has a hole in the inner cavity).

2. Classification by gear type:

- Spur cylindrical gear shaft: The simplest and most common type, with low manufacturing cost, used for transmitting motion between parallel shafts.

- Helical cylindrical gear shaft: Transmits motion between parallel shafts, providing smooth transmission, low noise, and high load capacity, but with axial force.

- Herringbone cylindrical gear shaft: Equivalent to combining two helical gears with opposite helix angles, the axial forces cancel each other out, suitable for heavy-duty applications, but with complex processing.

- Bevel gear shaft/umbrella gear shaft: Transmits motion between intersecting shafts. The gear teeth are conical in shape.

- Worm gear worm shaft: The worm itself is a special-shaped shaft (Archimedean worm, involute worm, etc.).

3. Classification by load nature:

- Spindle: Transmits torque and bears bending moment (most common gear shafts).

- Transmission shaft: Mainly transmits torque and bears little or no bending moment.

- Mandrel: Only bears bending moment and does not transmit torque (the gear can rotate on the shaft). At this time, the gear and shaft are usually not an integral part.

 

4. Classification by shaft support method (simplified classification):

- Cantilever gear shaft: The gear is located on one side of the two supporting bearings.

- Double-supported gear shaft: The gear is located between the two supporting bearings.

 

Classification dimensions	Main types	Features and applications
structure function	Unitary	Good rigidity, high precision, small and medium-sized gear shaftsare  mainstream
	Prefabricated / split type	Gears can be easily replaced, and large gears are low cost
	Combined type	Integrated functions (bearing position, gear, flange, etc.)
	The planet frame axis	Used for planetary gear transmission, support the planetary wheel
Type of gear	Drive/input shaft	Named according to its position in the transmission chain
	Straight cylindrical	Simple structure of parallel shaft transmission
	Spiral cylindrical	Smooth transmission, low noise, need to deal with axial force
	A human tooth cylinder	Eliminate axial force and high bearing capacity
	Bevel gear	Intersecting axe driving
	Worm shaft	The transmission ratio is large and is often used in the intermeshing shaft transmission
Nature of load	Spiale	Most commonly used to transmit torque and bear bending moments
	Transmission shaft	Mainly transmits torque (moment can be ignored)
	Arbor	Only bending moment is borne (separation of gear and shaft)
Support method	Overhead (under the span)	The gear is located on one side of the support point and has high stiffness requirements
	Two-way support (over the top)	The gear is located between the two supports and has good stiffness

 

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