As the use of off-highway electric vehicles and machinery continues to grow, so too does the importance of protecting the valuable and often expensive components that power them.
Used predominantly in rough, challenging, and hazardous environments, off-highway electric vehicles and their components face significant exposure to potentially harmful vibrations originating both externally and internally.
Sensitive and expensive electric components such as batteries, battery packs, and electric motors must be protected against environments that can cause erosion and damage leading to diminished performance and even failure.
Unmitigated vibrations waste energy while creating unwanted deformation and noise that can severely limit the operational lifespan of expensive physical components. Many of these vibrations occur as a byproduct of engine operation - whether internal combustion (ICE) or electric.
Luckily, successful solutions have been developed to mitigate vibration issues through a process called vibration isolation or damping. While many of these solutions were originally developed for use with internal combustion engines, they are proving increasingly valuable and beneficial within the electric motor space.
Here are the topics covered in this guide:
What is vibration and why is it so potentially harmful to electric vehicle components?
A vibration is a motion that repeats itself after an interval of time. This motion features periodic or random oscillations around an equilibrium point, turning potential energy into kinetic energy and back again.
Vehicles and machinery transfer vibrations and noise to their immediate environment. If nothing is done to mitigate this vibration, the effects on physical components and systems can be severe. Intermittent shocks and continuous vibrations are detrimental to machine longevity and functions.
When the physical components of both electric and IC engines (as well as many other non-engine related physical components and systems) are repeatedly exposed to the unmitigated kinetic energy of these vibrations, there is increased potential for fatigue, failure, and damage.
Because electric vehicles (EVs) tend to have more delicate components (such as battery cases, computer boards, and electronics) than their ICE counterparts, they are significantly more susceptible to the harmful effects of prolonged exposure to vibration.
Vibration and shaking can cause wear and tear on internal components, resulting in faulty operation and frequent breakdowns. Unchecked machine vibration accelerates wear rates (like reduced bearing life) and damages equipment. Vibrating machinery can also create noise, cause safety problems, and lead to the degradation of working conditions. Vibration can also cause machinery to consume excessive power while damaging valuable materials and resources.
So it makes sense that reducing the exposure of your EV’s components to vibrations offers a fail-safe way to increase the longevity and availability of expensive equipment, machinery, and vehicles - as well as their human operators.
Vibration theory describes the components of vibration.
Vibration theory establishes that a vibratory system is made up of three components: mass (M), spring (K), and damper (c). The analysis of the vibration process for this system can then be applied to the most complicated vibrating structure.
Mass, or inertia, is a system’s stored kinetic energy. Spring is the system’s means of storing potential energy. And damper is the means by which energy is gradually removed from the system. A system’s vibration alternates energy transfer between these potential and kinetic forms.
While machine parts and attached components move in multiple directions on various planes, there are two commonly used types of springs to maintain system integrity.
A steel spring has a linear relationship between force and deflection.
An elastomeric spring may or may not have a linear relationship between force and deflection - depending on the load. Non-linearity is often designed into elastomeric springs. These springs become deformed or bulge outward during compression.
Another significant difference is the stiffness of elastomeric springs is sensitive to the rate or speed of deflection. For example, if a rubber spring is deflected quickly, it will appear stiffer than if deflected slowly.
When force is applied in a standard coil spring, the spring compresses by some distance. This is called the spring rate. A drawback of this type of spring is its inability to dissipate energy quickly, allowing the input to resonate for some time.
A benefit of elastomers over metal springs is that they dissipate energy and allow for a variable spring rate. This means an elastomer is better suited to absorb energy from the system without transferring it like a steel spring system.
For more on elastomeric isolators, check out our Shock and Vibration Control blog.
Damping is the method by which the amount of energy a system produces is lowered. For example, a shock absorber in a car dampens (or lowers) the bouncing (vibration) created by uneven road surfaces by absorbing some of the energy of the interaction between the tires and the road.
While flexibility is often preferred over stiffness, too much flexibility or motion can bring problems.
Still curious? Here’s some more on Vibration Isolation Theory.
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The importance of reducing the effects of harmful vibrations originating from external environments.
The nature of off-highway use exposes vehicles and machinery to exponentially increased stressors, hardships, and complications than those faced by traditional, on-highway vehicles.
Off-highway electric vehicles must be able to operate effectively in often extreme environments. Electric vehicles and machinery are seeing increasing use in mining, construction, forestry, heavy transport, and agriculture. Some of the roughest terrain and hazardous environments imaginable.
To effectively operate within these environments, electric vehicles must mitigate vibrations and disturbing frequencies originating externally as well as internally.
The technologically advanced features of today’s heavy equipment and machinery require highly specialized solutions to isolate and protect critical sensors and electronics, avoiding costly downtime, repairs, and overhead. These and other high-exposure parts must be even further isolated than the rest of the machine.
Luckily, proper and effective vibration isolation can be achieved using affordable, customizable, and reliable component solutions - such as rubber mounts, bearings, and suspension systems. These rubber-based vibration solutions protect sensitive precision equipment, increase longevity, and reduce operator discomfort - all at a highly affordable price.
Operator Experience
One of the most important uses of vibration solutions centers around the effort to ensure operators and workers are protected, safe, and comfortable while working in and alongside off-highway vehicles and heavy machinery.
The heavy industry-related tasks required of off-highway electric vehicles often necessitate exposure to exacerbated vibrational effects such as turbulence, repeated heavy impacts, disturbing frequencies, and extreme road noise. Morale and productivity have been shown to decrease when workers experience unpleasant environments.
In terms of operator experience, the goal of vibration solutions is to promote operator comfort, health, and safety through the smooth performance of machinery.
Effective vibration isolation methods increasingly carry the potential to make operators feel like they’re at home sitting on a couch while operating heavy machinery and vehicles. Rubber-based vibration solutions can protect workers while optimizing performance.
And even as some vehicles move towards remote operation, the need to protect the sensors and other electronic components enabling this functionality will remain paramount.
Adverse Health Effects of Vibration Exposure
Health issues related to prolonged exposure to vibration include joint pain, bone damage, headaches, and motion sickness.
A common condition among operators of hand-held vibrating tools, Vibration-Induced White Finger (VWF), results in damaged blood vessels, weakness or numbness of the fingers, and potential loss of fine motor skills.
Exposure to whole-body vibration can cause fatigue, stomach problems, headache, loss of balance, and shakiness shortly after or during exposure. Daily exposure over several years can contribute to circulatory, bowel, respiratory, muscular, and back disorders.
Many studies have reported decreased performance in workers exposed to whole-body vibration.
Examples of Rubber-Based Solutions that Protect Operators from External Vibration Sources.
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Rubber isolation mounts isolate vibration sources such as engines, pumps, compressors, and auxiliary equipment.
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Flexible couplings used in a driveline minimize shift shock while protecting driveline components.
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Cab mounts and isolated seat suspensions provide additional isolation to an operator’s workspace.
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Suspension systems ensure friction from traveling over rough terrain is not transferred to drivers and operators.
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Protection brackets have successfully been used to minimize operator exposure to ICE disturbances - the biggest source of vibration in off-highway vehicles.
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While not vibration-related, custom-molded EMI shielding can prevent electronic noise from damaging equipment and operators.
The importance of protecting electric vehicle battery systems from potentially harmful vibrations.
The battery packs of electric vehicles are often the most susceptible to damage. Even minimal damage to a battery pack can result in reduced charging, storage, delivery, and even catastrophic failure of the vehicle or machinery.
As many a YouTube video has shown, damage to Lithium-ion batteries or battery packs can result in serious and dangerous consequences to both machinery and operators. Lithium-ion batteries are combustible and contain power cells that can cause short-circuiting if damaged. Damaged cells in a battery can experience uncontrolled increases in temperature and pressure (thermal runaway), which can lead to hazards such as shock and fire and expose workers to high-voltage components.
Rigorous and reliable protection of electric vehicle batteries is absolutely essential when the vehicles and machinery that rely on them are exposed to the environments that off-highway vehicles are made for.
Additionally, as batteries can represent a quarter or more of total vehicle weight, it is essential to find and utilize lightweight solutions (like rubber!).
Examples of Rubber-Based Solutions used to protect battery packs.
Rubber battery mounts allow batteries to be mounted to a chassis with significant control over vibrations.
Injection molding allows for the creation of battery and fuel cell seals that can more tightly seal a battery and prevent the loss of potentially hazardous electrolytes. These seals include vents capable of relieving excess gas pressure caused by short-circuiting, damage, or incorrect use.
As mentioned, elastomeric EMI shielding can provide needed protection against electromagnetic interference.
Rubber-based solutions also offer the potential for thermal management of an electric vehicle battery that can be managed in part by the sealing material. And rubber-based solutions are currently being developed to feature electrical conductivity for discharging and antistatic materials, enabling the removal of components such as metal conductors and reducing overall weight.
Battery gaskets provide environmental sealing and thermal insulation while providing fire protection and shielding against electromagnetic interference (EMI). The rubber-based materials of the gaskets impart properties such as chemical resistance, while rubber’s compressibility can fill the gaps between machined metal surfaces.
Protecting electric motors, sensors, and support systems from unwanted vibrations.
While electric vehicle motors are less susceptible to problems than their battery systems, protecting this vital component of a functioning vehicle under extreme circumstances is still extremely important.
And although vehicle motors may be more robust than their batteries, the sensors and support systems that run alongside them are often not. Rubber solutions offer lightweight, customizable solutions to mitigate shock on battery packs, sensors, and microchips.
The most cost-effective way to ruggedize fragile components is with well-established rubber bonding and components to various substrates.
And as the move to remote-operated machinery and vehicles increases, the importance of protecting components related to radar systems and sensors, such as LiDAR, will only grow. Rubber-based shock-dampening solutions represent one of the most efficient and effective methods of protecting these highly sensitive and expensive components.
Rubber-based solutions offer a tried, tested, and proven track record of success protecting off-highway and commercial vehicles and components against vibration.
While originally developed to address vibration issues in ICE powered vehicles and machinery, rubber-based solutions can be easily and cost-effectively adapted to their electric counterparts.
Why are rubber vibration isolation mounts so effective?
Vibration mounts are commonly used in machinery because they relieve vibrations posing operational challenges and deteriorating equipment. This is considered “passive isolation” and represents a passive rather than “active” technique to isolate vibration.
Vibration impacts introduce large forces and stresses that can cause degraded performance and mechanisms' early failure. Adequate engine support and reduced looseness limit structural vibrations. Proper mounting and accurate support design reduces engine vibrations and associated problems. Both internal combustion engines and electric motors are large, concentrated masses that, if not adequately supported, will cause vibrations that will be transferred to supporting structures.
Different types of vibration mounts:
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Two-piece vibration mounts
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Anti-vibration pads
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Small industrial engine mounts
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Plateform mounts
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Rubber flex bobbin sandwich mounts
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HVAC neoprene mounts
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Bushings
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Large sandwich mounts
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Conical mounts
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Grommet isolators
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DynaflexⓇ couplings
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Machinery mounts
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Flex-bolt sandwich mounts
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Binocular engine mounts
Because noise, vibration, and harshness (NVH) in vehicles grow increasingly complex as technology advances, thoughtful, customizable solutions must be used to solve them.
Elastomeric mounts provide simple, reliable, cost-effective solutions to isolate vibration and shock, accommodate motion, and decrease noise.
Benefits of using engine mounts even with an electric vehicle include:
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Reduces vibration-induced pain in equipment operators
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Increases the durability of the equipment
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Reduces necessary repairs, and replacements
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Lowers noise emission
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Increases machine precision and task efficiency
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Reduces OEM warranty costs
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Keeps equipment running longer = more productivity = more profit
The size and shape of vibration mounts are paramount to proper functioning.
The size of a vibration mount and associated rubber pieces is important because the less rubber, the less load it can bear. While larger elastomers can accommodate more load, they also introduce increased motion. Accurate measuring processes are necessary to ensure that pieces not only fit but also possess the flexibility and durability to avoid frequent replacement.
The shape of a vibration mount is vitally important due to the rubber being under compression. Because pieces must dampen or absorb shock from motion across multiple planes and directions, they often require custom designs and shapes.
Want to learn more about mounts? Check out our blog: What is an Engine Mount and How Does it Work?
Rubber Motor Mounts
Rubber motor mounts are currently used to absorb shocks, vibrations, and machine noises in heavy and light equipment such as agriculture, construction, and highway trucks.
Because of its resiliency, rubber is ideal for shock absorption in equipment that moves around significantly or creates substantial vibration or noise. Rubber parts isolate heavy vibration, absorbing energy from an engine and reducing high frequencies to protect surrounding parts from damage.
Rubber engine mounts are typically placed underneath and around the engine. They absorb the vibration and disturbing frequencies from the engine, reducing strain and damage that could be caused to surrounding parts.
Find out even more benefits of rubber engine mounts!
How to choose the suitable vibration isolation solution?
So you need a vibration isolator for your application but don’t know where to start. With part options seemingly limitless and specifications rarely easy to understand, it’s clear choosing a vibration isolator is an imposing task.
Many suppliers will refer you to their catalogs and leave you to figure out the rest, leading to suboptimal performance, returns, and even catastrophic failures.
Choosing the wrong isolator can amplify input rather than isolate it.
Vibration Isolator Specs Buyers Should Consider
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Weight limits: the weight that individual isolators can support and still work effectively
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Vibration dampening: the process of dissipating vibration into heat, which varies by material
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Natural frequency: the frequency at which a component or system naturally vibrates
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Transmissibility: the ratio of a vibration when entering a system to its vibration when exiting
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Temperature sensitivity: how the ambient temperature impacts individual parts
Not to mention many more application-specific criteria to consider…
Luckily, we at RPM have great experience solving Noise, Vibration, and Harshness. Many of RPM’s vibration control products are specifically designed for applications that include electrical motors, diesel engines, fans and blowers, material handling equipment, compressors, measuring instruments, punch presses, lathes, and various other industrial equipment.
Schedule a consultation with our sales team, and we’ll figure out the perfect fit for your needs.
Conclusion. An affordable and reliable legacy solution for the growing use of electric off-highway vehicles and machinery.
Rubber solutions are multi-faceted, customizable, and affordable.
One of the fastest-growing automotive markets in North America, the electric vehicle (EV) segment is driving rubber parts manufacturers to match its growth in new product development and innovation.
Lithium-ion (Li-ion) batteries, the power source of choice for the new generation of electric, hybrid, and plug-in hybrid vehicles, require cushioning, sealing, and vibration isolation that must perform reliably under tough conditions.
Battery packs, sensors, and other electromechanical components are more fragile and react poorly when damaged. A pierced or otherwise damaged vibration battery can explode or become a fire hazard. These parts also must be isolated for fatigue life. Posing new challenges for specialists in traditional combustion engine manufacturing.
As the development and implementation of off-highway electric vehicles continue to grow, engineers and developers are increasingly tasked with incorporating safe, reliable, and cost-effective isolators into machine designs.
The reality is that vibration and its harmful effects are the same whether a vehicle utilizes an internal combustion engine or electric motor. The difference is the components being affected.
At RPM, we utilize our extensive and wide-ranging experience in industrial rubber solutions to match our customers with the perfect parts to fit their unique needs.
Our vibration control products offer a low-cost way to provide isolation, absorb shock, and protect valuable components. Our products can maximize the operating life of costly and sensitive equipment and vehicles, ensuring that your investment is maximized.
In the rapidly developing world of off-highway electric vehicles, it quite literally pays to utilize cost-efficient, dependable, and safe solutions wherever possible. Our rubber-based vibration control products are exactly that.
Reach out and one of our experts will work with you to find or create the perfect solutions for your electric vehicle engineering and development needs.
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