Involute Cylindrical Gear & Gear Shaft Constant Velocity Ratio Center Distance

Product Specification

Involute Cylindrical Gear & Gear Shaft Constant Velocity Ratio Center Distance Flexibility

Part 1: Involute Cylindrical Gear

1. Introduction
The involute cylindrical gear is the most fundamental and widely used type of gear in modern mechanical power transmission. Its tooth profile is based on the involute curve. This geometry ensures a constant velocity ratio, smooth operation, and is insensitive to small variations in center distance, offering excellent meshing characteristics. It is used for power transmission between parallel shafts (external or internal meshing).

2. Advantages

• Constant Velocity Ratio: The involute profile guarantees a constant instantaneous velocity ratio, ensuring accurate motion transmission, high smoothness, and reduced impact and noise.

• Center Distance Flexibility: Slight variations in the installed center distance do not affect the transmission ratio, which lowers the required precision for manufacturing and assembly, enhancing applicability.

• Mature Manufacturing Process: Standardized cutting tools and mature manufacturing technologies (e.g., hobbing, shaping, grinding) make high-precision, mass production relatively easy and cost-effective.

• High Load Capacity: Tooth contact is linear, allowing for the transmission of significant power and torque.

3. Key Technical Parameters

• Module / Diametral Pitch: The most fundamental parameter determining tooth size.

• Number of Teeth: Determines the pitch diameter together with the module.

• Pressure Angle: Commonly 20° (modern design) and 14.5° (older design), affecting gear strength and root thickness.

• Face Width: The axial width of the gear, influencing load capacity.

• Accuracy Grade: Rated per ISO or AGMA standards (e.g., ISO 1328 Classes 5-9). A lower class number indicates higher precision and smoother operation.

• Profile Shift Coefficient: Used to avoid undercutting, adjust center distance, or improve the strength balance between mating gears.

4. Applications
Extremely widespread, found in almost any field requiring power transmission:

• Automotive Industry: Gearboxes, differentials.

• Industrial Equipment: Reducers, machine tools, conveyor systems, robot joints.

• Consumer Appliances: Washing machines, power tools.

• Aerospace: Engine accessory drive systems.

Part 2: Gear Shaft

1. Introduction
A gear shaft is a special component where the gear and the shaft are manufactured as a single integrated piece. It is not simply a "gear + shaft" but a unified functional part. It is typically used when the root diameter of the pinion is close to the shaft diameter, or when extremely high operational rigidity and reliability are required.

2. Advantages (Compared to separate gear and shaft)

• High Strength and Rigidity: Avoids stress concentration and fretting wear associated with keyed connections. The monolithic structure can withstand greater loads and torque.

• High Reliability: Eliminates the risk of failure in connecting elements like keys or pins. The simpler structure has fewer potential points of failure.

• Compact Structure: Saves installation space, leading to cleaner designs.

• Excellent Alignment: The gear and shaft sections are naturally coaxial, avoiding assembly misalignment.

3. Key Technical Parameters
The parameters of a gear shaft include its parameters as a gear (module, number of teeth, pressure angle, etc.) and its parameters as a shaft:

• Support Type: Rotating shaft (transmits torque and bears bending moments), stationary axle (bears bending moments only).

• Material & Heat Treatment: Typically made from alloy steels (e.g., 40Cr, 20CrMnTi) and treated with processes like quenching and tempering or carburizing to ensure hard tooth surfaces and a tough core.

• Journal Dimensions & Tolerances: Diameter and precision of the sections that mate with bearings.

• Keyway / Spline (if applicable): For connecting to other components.

4. Applications
Commonly used in applications with high demands on space, weight, and reliability:

• Reducers / Gearboxes: Especially the high-speed pinion is often made as a gear shaft.

• Automotive Engines: Camshafts, oil pump drive shafts.

• Aerospace: Transmission systems requiring high reliability.

• Precision Instruments: Applications demanding high alignment and low vibration.