Coil springs are essentially mechanical devices used in various systems, including automotive components and industrial machinery. They absorb shock, maintain force, support structures, and facilitate controlled movement.
Made from elastic materials like metal wire, coil springs can compress, extend, or rotate under load, returning to their original shape once the load is removed. Their properties allow them to store energy temporarily and release it as needed, managing force and motion in mechanical systems.
Well, in this reading, I’ll be exploring what a coil spring is, its application, parts, diagram, types, construction, materials, and how it works.
Let’s begin!
What is a Coil Spring?
A coil spring is a mechanical device made from elastic materials like metal wire, coiled into a helical shape. This design allows the spring to compress, extend, or rotate under load and return to its original shape once the load is removed.
Coil springs store energy temporarily and release it as needed, providing solutions for managing force and motion in mechanical systems. They are typically used to store energy, absorb shock, or maintain force between contacting surfaces.
The spring characteristics depend on the shear modulus, which is the material’s shear modulus. Coil springs can also be used as torsion springs, subjecting the spring to torsion about its helical axis.
The Young’s modulus of the material can be used to determine the spring characteristics. Coil springs are found in various items, including farm equipment, toys, and trampolines.
Applications
Coil springs are crucial in heavy-duty machinery across various sectors, including the automotive industry, construction, and agricultural machinery.
They enhance performance, safety, and durability in these applications. In the automotive industry, coil springs are used in car suspension systems to ensure stability, shock absorption, and comfort. They are designed to withstand harsh driving conditions and daily use, ensuring the safety of vehicles like heavy-duty trucks.
In construction equipment, coil springs are used to control vibration, maintain equipment alignment, and reduce wear and tear. They are also used in concrete mixers, truck tailgates, vibrating screens, and feeders.
In agricultural machinery, coil springs are used to manage uneven terrain and heavy loads, maintain stability, improve ride quality, and extend machinery lifespan.
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Parts and Diagram
Types of Coil Springs
The three common types of coil springs include compression springs, tension springs, and torsion springs.
Compression Spring
Compression springs store and release energy when subjected to a compressive force. They absorb shock and maintain force between components.
Compression springs are used in automotive suspension systems, industrial machinery, valve and actuator systems, and everyday household items like mattress springs. When the force is removed, energy is released, and the spring expands to its original length.
Tension Spring
Tension springs, also known as extension springs, work by resisting a pulling force and absorbing and storing energy. They create a return force when extended, bringing components back to their original position.
In their unloaded state, adjacent coils touch, but initial tension must be overcome before extending.
These springs are used in various industries, including trampolines, retracting seat belts, garage doors, power tools, motorsport throttle linking systems, and mining vibrating screens.
Torsion Spring
Torsion springs are a mechanism that controls rotational movements by applying torque or rotational force to their arms. The energy stored during this twisting motion is released as the spring returns to its original position.
They are used in various applications, such as pegs for gripping clothes, garage door mechanisms, hinges for closing doors, mouse traps for snapping mechanisms, watches for winding mechanisms, and vehicle suspension systems for stabilising and controlling movement.
Design and Material
Design considerations for heavy-duty applications involve ensuring springs can withstand high stresses without failure.
This requires careful consideration of materials, spring rate, and performance under extreme conditions, ensuring durability, efficiency, and performance in these applications.
The spring rate, or stiffness, is a crucial factor in the performance of a spring under load. It indicates the amount of load required to compress the spring by a unit of length.
Materials like stainless steel, carbon steel, chrome silicon, chrome vanadium, Inconel, elgiloy, titanium, phosphor bronze, and beryllium copper are commonly used in coil spring manufacture due to their varying strength, elasticity, corrosion resistance, and fatigue life.
High-grade steel alloys are preferred for their excellent tensile strength and durability, while stainless steel is preferred for environments where corrosion is a concern.
How Do Coil Springs Work?
Coil springs are essential components in various applications, storing energy to release it, absorb shock, and maintain force between surfaces. The spring rate is the measurement of how much a coil spring can hold until it compresses 1 inch (2.54 cm), typically specified by the manufacturer.
Metal coil springs are made by winding a wire around a shaped former, such as a cylinder, to form cylindrical coil springs.
For vehicles, coil springs are typically made of hardened steel. An auto-coiler machine takes heated spring wire and feeds it onto a lathe with a metal rod with the desired coil spring size.
The wire is guided onto the spinning rod and pushed across the rod to form multiple coils. The spring is then ejected from the machine, cooled in oil, and tempered to lose brittleness.
The coil size and strength can be controlled by the lathe rod size and material used. Different alloys are used to achieve specific characteristics like stiffness, dampening, and strength.
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Symptoms of a Bad Coil Spring in a Car
The following are the symptoms of a bad coil spring in a car:
Strange noises
Investigate any strange noises you notice while driving as soon as you can. On uneven surfaces, you’ll hear a clunking or knocking sound if your coil springs are slowly corroding.
Extreme swinging
This frequently occurs when you have unbalanced wheels or uneven tires. Your suspension’s components will collide with one another, changing the angles of travel. This may cause your automobile to bounce excessively, steer unevenly, or wobble more than usual.
Irregular wheel arches
Looking at your car’s corners is another way to determine if the coil springs have deteriorated. Get a tape measure and measure the distance between your wheel arches and the ground if one corner appears to be lower than the rest. If the discrepancy is significant, a coil spring may be damaged.
Increased braking distance
The friction between the tires and the road decreases as your coil springs corrode. This results in longer stopping distances, especially in ice conditions, and poses a serious risk to you, other drivers, and pedestrians.
What Causes a Coil Spring to Break?
The following can cause a coil spring to break:
Coating Damage and Corrosion
A flexible plastic coating is applied to coil springs to assist in preventing corrosion of the metal. But over time, due to continuous compression and being struck by road stones, this coating may become harmed, allowing rust to develop on the coil.
When this occurs, the coil may become fragile and even shatter. Regularly driving in tough terrain will increase the likelihood of a break.
Blown Tires
Uneven wear on your suspension from unbalanced wheels could result in a broken coil. Meanwhile, a flat or blown tire can put a lot of strain on your suspension system and perhaps damage a coil.
Your steering and braking systems may be harmed by a broken coil spring.
Fluid Leaks in Struts
When a strut, which typically consists of a shock absorber and a spring, leaks hydraulic fluid, it loses its ability to function, which puts greater strain on the neighbouring coil and raises the risk of a break.
If your vehicle makes more noise when you drive over dips and bumps, you may have a hydraulic fluid leak. Reduced hydraulic pressure may result in springs contacting other suspension parts, harming brake lines or even the exhaust system.
How to Prevent Coil Spring Corroding
The following will help you prevent a corroding coil spring in your car:
Never Overburden your vehicle
Avoiding overloading your vehicle not only helps you use less fuel but also keeps your coil springs from corroding over time and breaking.
Maintaining excellent tire condition
Regular tire maintenance and inspections will prevent your coil springs from experiencing excessive pressure. By doing this, you can keep them in good shape and stop them from cracking.
Be cautious when navigating potholes and bumps
Your coil springs are put under stress when you drive recklessly on bad roads or into potholes; the more carefully you drive, the longer your coil springs will endure.
Clean the vehicle’s underneath
Regularly clearing out any accumulated grit, dirt, or ice underneath your car during the winter, whether with a hosepipe or a pressure washer, keeps your coil springs in top shape.
It makes a huge difference to understand the factors that lead to coil spring failure and how to stop them from corroding. Our step-by-step instruction explains how to prevent the paint flaw from corroding and turning rusty if you’ve discovered a spot that needs to be touched up.
How Much Does It Cost to Replace a Coil Spring?
Typically, coil springs only cost $55 to $150 per piece. But if you replace all four, the cost quickly rises to between $220 and $600. If you are unable to repair the coil springs yourself, you must hire a mechanic, who will likely charge an additional $350 to $800 for a full replacement.
This cost may be reduced if you only want to replace the front or back pairs of springs. However, you could also need to include other services, such as shock replacement.
