Elastic Springs and Bearings in Mechanical Systems
Elastic Springs and Bearings
Elastic springs and joints are used to absorb energy or shock loads, acting as elements in an engine or power source, and to produce a force or pressure.
Springs
Springs are items that possess the property of *elasticity*, meaning the ability to deform when subjected to an external force, absorbing energy, and then returning to their initial position, releasing the absorbed energy when the force is removed.
The most important types of springs include:
- Tensile (or Traction) Springs: A thread made of helically rolled material, designed to withstand forces that tend to stretch them.
- Compression Springs: Similar geometry to tensile springs, but designed to resist forces that attempt to compress them.
- Torsion Springs: Rolled similarly to the previous types, but with differently shaped ends to resist torsional forces.
- Leaf Springs (Crossbow Springs): Flat sheets of steel bent in half and joined by a flange, stacked one on top of the other. The fixations at their ends are joined by rotating support arms to allow the spring to stretch.
- Spiral Springs: Designed to accumulate or absorb a rotational moment of a shaft that is joined to the inner corner of the spring, while the other end is attached to a bench or support.
- Rubber Springs: Rubber crumbs can work in compression and shear, with the advantage of significantly reducing the weight of the machine compared to a steel spring.
Bearings
Bearings (also known as *rolling bearings*) are intermediate elements mounted between two bodies of a mechanism that rotate relative to each other. They ensure minimal friction between them and, at the same time, ensure that these two bodies remain united.
Bearing Parts
- Outer Ring: The outer ring is pressure-fitted within the element or rotates within the fixed component. It serves as the inner raceway or track for the rolling bodies.
- Inner Ring: Its interior may be linked to the rotating element or the fixed component, and serves as the outer raceway for the rolling bodies.
- Rolling Bodies: These create the friction that causes the bodies to roll in turn.
- Separators (Cages): Keep the rolling bodies equidistant from each other.
Forces on Bearings
- Radial Force: When the force the bearing has to hold is perpendicular to the imaginary line that passes through the center of the bearing.
- Axial Force: When the force is parallel to this imaginary line or center.
- Oblique Force: A combination of radial and axial forces.
Classes of Bearings
- Deep Groove Ball Bearings: Notable for high rotational speeds, minimal friction between the balls and tracks, and are very economical.
- Single Row Angular Contact Ball Bearings: Designed to receive pressure on the oblique line of the bearing axis. Can handle radial and axial loads, provided the latter are assembled in opposition to other bearings to receive thrust in the opposite direction. If this bearing had two rows of balls, it could withstand axial loads from both sides.
- Cylindrical Roller Bearings: Support large radial loads and withstand high speeds. They have the advantage of allowing the shaft to move axially, within certain limits.
- Tapered Roller Bearings: The oblique position of the rollers and raceways makes them suitable for withstanding both axial and radial loads. Requires the accompaniment of another bearing mounted in opposition to support axial forces.
- Needle Bearings: Enable lightweight constructions and require little space, in addition to allowing good lubrication.