Machine Drawing and Design Notes

Shaft Couplings

Purpose

  • Power Transmission: Connects and transmits torque between shafts.

  • Misalignment Compensation: Allows for variations in shaft positioning to prevent mechanical failure.

    • Types of Misalignment:

    1. Parallel Misalignment: Centerlines are parallel but offset, causing stress.

    2. Angular Misalignment: Centerlines intersect at an angle, leading to vibrations.

    3. Axial Misalignment: Shaft ends are misaligned due to temperature changes.

Types of Couplings

  1. Rigid Couplings:

    • Designed for exact alignment.

    • High torque capabilities; does not allow for misalignment.

  2. Flexible Couplings:

    • Accommodate for misalignment.

    • Various types include jaw, disc, gear, and tire couplings.

  3. Fluid Couplings:

    • Use hydraulic fluid for smooth torque transmission.

  4. Magnetic Couplings:

    • Torque transmitted via magnetic fields, providing a non-contact method.

Rigid Couplings

  • Characteristics: Perfect alignment, heavy-duty applications.

    • Types: Flange, Sleeve Couplings

    • Applications: When shaft positioning is critical.

Flexible Couplings

  • Utility: Allows for absorption of shock/vibration, maintaining torque transmission.

  • Characteristics: Different flexibility levels, helps protect equipment.

Universal Joints

Description

  • Classic Universal Joint:

    • Designed for angular shaft connections.

    • Simple, robust, and transmits torque efficiently but has fluctuating speed.

Types of Universal Joints

  1. Cardan Joint (Hooke Joint):

    • Transmits torque between angled shafts with fluctuations in output speed.

  2. Constant Velocity (CV) Joints:

    • Maintains constant speed at various angles, suited for drive shafts in vehicles.

Applications

  • Common in older vehicles, and machinery requiring variable output without speed fluctuation.

Bearings

Function and Purpose

  • Reduce friction between moving elements, supporting and guiding moving parts.

  • Critical in applications needing smooth rotational or linear movement.

Types of Bearings

  1. Plain Bearings: Utilize sliding surfaces, often require lubrication.

  2. Rolling Element Bearings: Use balls or rollers; reduced friction and capable of handling higher loads.

Rolling-Element Bearings Types

  1. Ball Bearings: Spherical balls as rolling elements; suitable for high-speed and lighter loads.

  2. Roller Bearings: Cylindrical rollers for higher load capacities.

Plain Bearings Characteristics

  • Include sleeve bearings, bushings, and thrust bearings.

  • Key factors: Design, lubrication, material selection, clearance, and surface finish.

Applications

  • Found in engines, machinery, appliances, automotive components.