high frequency screen engine

high frequency sizing screens

Widely used in fine wet screening applications, these high frequency screening machines comprise of up to five individual screen decks positioned one above the other operating in parallel. The stacked design allows for high-capacity units in a small footprint. The flow distributor splits the feed stream evenly to the individual polyurethane screen decks (openings down to 45 pm) where feeders distribute the stream across the entire width (up to 6 m) of each screen. Dual vibratory motors provide uniform linear motion to all screen decks. The undersize and oversize streams are individually combined and exit toward the bottom of the Stacked Sizer. Repulp sprays and trays arc an optional addition in between screen sections, which allow for increased screen efficiency.

By classifying by size-only, screens compared to hydrocyclones, give a sharper separation with multi-density feeds (for example, in PbZn operations), and reduce overgrinding of the dense minerals. Operations that replaced hydrocyclones with stackedhigh frequency screening machines in closing ball mill circuits can result in a decrease in the circulating load from 260% to 100% and 10 to 20% increase in circuit throughput.

The high capacity Stacked Sizing/screening machine consists of up to five decks positioned one above the other and all operating in parallel. Its use together with urethane screen surfaces as fine as 75 microns (200 mesh) has made fine wet screening a practical reality in mineral processing operations worldwide. The application of this technology in closed circuit grinding is demonstrated with specific application examples.

Screening is the process of separating particles by size and fine screening typically refers to separations in therange of 10 mm (3/8) to 38 microns (400 mesh). Fine screening, wet or dry, is normally accomplished with highfrequency, low amplitude, vibrating screening machines with either elliptical or straight-line motion. Various types ofwet and dry fine screening machines and the factors affecting their operation have been discussed previously.In fine particle wet screening, the undersize particles arc transported through the screen openings by the fluid andthe fraction of fluid in the slurry will therefore affect the efficiency of the separation. From a practical standpoint, the feed slurry to a fine screen should be around 20% solids by volume to achieve reasonable separation efficiency. Asmost of the fluid passes through the screen openings rather quickly, the fine screening process can be completed in ashort screen length. Therefore screen width, rather than screen area, is an important design consideration for fine wet screening.

Recognition of this concept led to the development of multiple feed point fine wet screening machines, or example, the Multifeed screen consists of three screen panels mounted within a rectangular vibrating frame and is actually three short screens operating in parallel. Each screen panel has its own feed box and the oversize from each panel flows into a common launder and then to the oversize chute. Similarly, the undersize from each of the three panels flows into the undersize hopper. The popular 1.2 m (4 ft) wide by 2.4 m (8 fl) long version has a total effective width of 3.0 m (10 fl) In general, multiple feed point machines have been shown to have 1.5 to 2 times more capacity than a single feed point machine of equivalent size and screen area.

Expanding further on this concept, the Stacked screening machine was introduced in 2001. With a capacity considerably greater than any other type of fine wet screening machine previously available, the Stack Sizer has up to five vibrating screen decks operating in parallel for a total effective width of 5.1 m (17 ft). The decks are positioned one above the other and each deck has its own feed box. A custom-engineered single or multiple-stage flow distribution system is normally included in the scope of supply to representatively split the feed slurry to each Stacked screen and then to the decks on each machine. Ample space is provided between each of the screen decks for clear observation during operation and easy access for maintenance and replacement of screen surfaces. Each screen deck, consisting of two screen panels in series, is equipped with an undersize collection pan which discharges into a common launder with a single outlet. Similarly, the oversize from each of the screen decks collects in a single hopper with a common outlet large vibrating motors rated at 1.9 kW (2 5 HP) each and rotating in opposite directions produce a uniform high frequency linear motion throughout the entire length and width of all screen decks for superior oversize conveyance.

As mentioned above, the fluid passing through the openings carries the undersize particles through the screen openings. The screening process is essentially complete when most of the fluid has passed through the openings. Any remaining undersize particles adhere to the coarse particles and are misdirected to the oversize product An optional repulping system is available for the Stack Sizer in which spray water is directed into a rubber-lined trough located between the two panels on each deck With this feature, oversize from the first panel is reslurried and screened again on the second panel. This repulping action maximizes the correct placement of undersize particles and its use will depend upon the particular objective of the screening machine.

To date, 1000s of screening machines are in operation at mineral processing plants worldwide. Dry mass flow capacity typically ranges from 100 to 350 t/h. This is roughly equivalent to 3 or 4 of the older style Multi-feed screens discussed above Like all screening machines, capacity depends upon many factors such as screen panel opening, weight recovery to oversize, the amount of near-size particles, particle shape, and slurry viscosity.

Sizers are for high capacity in a short compact machine. Generally you can make good cuts or separations with high efficiency. If you need near absolute 99.9% precision cuts, then a sizer cannot do that, and most inclined screeners also cannot. So that is why it is very important to understand what the separation goal is before selecting a screener. You cannot have high capacity and high accuracy + 99.9 in the same machine! This machine does not exist! A sizer generally can accomplish a similar separation of a single inclined screen in 2 or 3 screens, and 1/3 the length. of course a lot depends on the PSD, and how close the remaining particles are on each side of the desired cut.

compare high frequency screens & hydrocyclones

Hydrocyclones are currently the most commonly used classifiers in wet closed circuit grinding systems. Some recent papers, however, give evidence that high frequency vibrating screens can be a viable alternative to hydrocyclones for a wide variety of grinding applications.

In principle, classifier selection for closed circuit grinding should be based on an evaluation of the advantages provided by each classifier type being considered (e.g., increased circuit capacity, improved water balance, reduction in undesirable fines, etc.) versus costs (capital, installation, operating). Furthermore, the evaluation should be made for those conditions of optimal mill/classifier performance which give the desired product quality. This requires a detailed knowledge of the factors which affect the performance of the classifier types of interest. .

The feed materials used for the pilot plant study were three different limestones designated here as limestones A, B and C, having Bond Work Indices of 6.4, 7.6 and 11.9 kW-hr/short ton, respectively. All three materials were used for closed circuit demonstration testing; limestone A was the feed materialused for model development and validation.

When constructing models for mills and classifiers it is customary to split the particle size range into geometric intervals according to the 2 sieve series and number the largest size 1, the second largest size 2, etc., down to the smallest (sink) size n. This is done because material in one of these size intervals appears to behave like a homogeneous material, to a sufficient approximation.

Using this basis, models for ball mills are constructed as mass-size balances incorporating the concepts of specific rates of breakage Si, and primary progeny fragment distributions bij. Si is the specific rate of breakage of size i, with units of fraction per minute being convenient for ball mills; bij is the weight fraction of progeny fragments which appear in smaller size i as a result of primary breakage of larger size j. Combining these concepts into a size mass balance for a fully mixed batch mill gives the equation set known as the batch grinding equation:

where wi(t) gives the particle size distribution as a function of grinding time t. Reid showed that the concept of residence time distribution (RTD) could be immediately applied to a steady-state continuous mill to give

where (t)dt is the fraction of feed which leaves the mill at time t to t+dt after admission, and (t) is thus the RTD (units of fraction per unit time); pi is the fraction of the mill product of size i. The solution of Equations 1 and 2 for known feed size distribution and known (t) can be put as

where fj is the weight fraction of the mill feed of size j and the dij is a matrix of transfer parameters. When expressed as Equation 3, the function of the simulation model is to compute dij (which contain the Sj, bij and RTD) for the mill design and operating conditions of interest.

The objective selected for pilot plant simulations was to determine the maximum circuit product rate Q when producing product size distributions with a specified 80% passing size in the range of 25 to 90 microns. This objective is relatively simple to accomplish since there are no constraints due to specifications on the density of the fine product slurry. Note, however, that simulations performed without regard to specifications on the circuit water balance may not be realistic for many applications.

The reasons for these results are clear upon examination of the corresponding classifier performance data. Figure 8 shows the classifier bypass data corresponding to the results in Figures 5 and 6. Lower bypass tends to give higher Q, by reducing overgrinding of fines and giving a steeper product size distribution as shown in Figure 7. Higher sharpness index has the same effect and as Figure 9 shows the SI is higher for the screen above about 45 microns. The sum effect of bypass and SI is to favor screens for 80% passing sizes above 40 microns.

It was of interest to the authors to evaluate high frequency screens versus hydrocyclones for the wet, closed circuit grinding of a coal in a full-scale ball mill circuit. The coal feed was a crusher product having a top size of 9.5 mm. The specification for the ground coal product was 95 weight percent smaller than 160 10 microns and 80 weight percent smaller than 110 10 microns, with no specification for the solids density of the circuit product.

Use of this hydrocyclone model in effect set the minimum size of mill for the evaluation. That is, since the model is for a particular size of hydrocyclone operated over its normal range of slurry feed rate, which Slechta and Firth report to be 250-500 liters/min at 9 to 35 weight percent solids, the mill required for a single mill/hydrocyclone system had to be large enough to provide, the solid rates necessary for normal operation of the hydrocyclone. For simulation this is necessary in order to establish dimensions for a mill and therefore allow the appropriate Si correcting factors to be calculated. For larger mills than this minimum size, one would use a multiple hydrocyclone arrangement. From the Slechta and Firth report, the maximum hydrocyclone solids feed rate would be about 15 tph of coal. Assuming a reasonable circulation ratio of 2.5, the minimum size of mill appropriate for evaluation was determined to be 1.37 m in diameter for an assumed mill-to-length ratio of 1.5.

Over most of the product size range examined, particularly in the range of interest, 80 weight percent passing 100 to 120 microns, high frequency screening with the DF 88 or DF 105 cloths gives higher Q than when the hydrocyclone is used. That the screen and hydrocyclone results are not so different is due to the relatively low hydrocyclone bypass, a result of feeding the hydrocyclone relatively dilute slurries, to obtain dilute fine products.

It is interesting to examine the costs of high frequency screening versus hydrocyclones for this grinding application. In general these costs are a function of the number of units required and capital cost per unit, installation costs, and operating costs. For high frequency screening, the data presented by Rogers and Brame and substantiated by Derrick show that a Derrick screening machine fitted with DF 88 screen cloths can classify about 500 liters/min of the coal slurry per square meter of screening area.

high frequency screens and flickering laurent's choice

A high frequency monitor means more image rendered on your screen per second. Example in hand, if you have a 60 Hertz screen, your screen will refresh its rendered image 60 times per second. If you have a 100 Hertz refresh rate, then your screen will run at 100 Frames Per Second (FPS).

The only problem is that an abnormal amount of people report having issues with high refreshing rate monitors. No matter the monitor or video card monitor brand, thousands upon thousands of otherwise happy gamer are reporting the very same issue: Flickering (or black screens).

The epileptic nightmare. Imagine going on with your daily business, or playing your favorite video game, and suddenly, your screen goes black.. then comes back.. and then black again, doing so at irregular interval and without obvious reasons.

Your first reflect is to check that your display cable is securely in pace both on your monitor and your video screen, you may even reinstall your video card drivers, or try to OC your GPU. Every one seems to have the same approach.

Before going on to forums and start endless threads, which of some are a decade old with posting of a this very week, make sure to have what it takes to run a high frequency game and high frequency monitor.

Here is the funny thing. To take full advantage of a high refreshing rate, you need a game to output the same or greater Frames Per Second. For example, if you have your screen refresh rate set at 100 Hertz, and your game output only up to 60 FPS, then obviously, you will only see experience a 60 FPS game. You will need enough memory, CPU process, GPU horse power to match or over perform the monitor refreshing rate.

NVIDIA did try (somewhat successfully) to address this with its G-SYNC chip-set which it installs in both its newer GPUs and high performing monitors. This allows the GPU and the monitor to sync both the GPU performances and the monitor refreshing rate to have a matching FPS and refreshing rate as much as possible.

It seems almost trivial to say so, but make sure that your video card can handle such refreshing rates (if produced after 2011, they usually do) and that they are DisplayPort 1.2 compliant at the very least.

To run a high refresh rate monitor, ONLY the Display Port can do so! The HDMI (even 2.0) will lock your frequency at 60 Hertz or below. Any attempt to run your config at a higher refresh rate, will result in an out of range message on your screen.

Display Ports cable ARE confusing. Unlike USB plug, they do not have any color codes, or marking to identify which generation they belong to. Even their boxing seems to purposely not report what gen they are from.

The flickering effect that you so dread is due to the fact that you are using a 1.0 or 1.1 Display Port cable. These cables do not provide enough bandwidth to convey, say, 144 frames per second of 2k resolution. And when you do try, of course, your cable cannot keep up with the massive GPU output and what the monitor needs, to keep a steady flow of video output.

IIf you are going with a high-en gaming monitor, I would go straight to a 1.4 HBR3 cable. They are more expensive (about 35 USD), but you are set for generations of monitors and video cards to come. This new standard can not only deliver 240 Hertz refresh rates to a 4k panel, but it can cater to 5k and 8k panels as well! In short it is future proof!

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top 10 vibrating screens of 2021 | screening materials - rethinkrethought

A vibrating screen is a machine made with a screening surface vibrated precisely at high speeds. It is utilized particularly for screening mineral, coal, or other fine dry materials. The screening execution is influenced essentially by different factors, for example, hardware limit and point of inclination, in which the performance can estimate by screening effectiveness and flux of the item. While this type of machine is doesnt use for DIY purposes, you may require this for industrial purposes. It is especially essential in the mineral processing industry. If you are considering buying one, check out this article and learn which vibrating screen machine may be perfect for you and your project.

Twofold vibrating engines drive a linear vibrating screen. At the point when the two vibrating engines are turning synchronously, and contrarily, the excitation power creates by the whimsical square counterbalances each other toward the path corresponding to the pivot of the engine. Then, it covers into a resultant power toward the path opposite to the hub of the engine. So, the movement becomes a straight line.

The elliptical vibrating screen is a vibrating screen with an elliptical movement track, which has the upsides of high proficiency, high screening precision, and a wide scope of use. Contrasted with the conventional strainer machine of similar detail, it has a bigger handling limit and higher screening productivity.

A circular vibrating screen is another sort of vibrating screen with a multi-layer screen and high proficiency. As per the kind of materials and the prerequisites of clients, you can use its multiple screening plates. it were introduced in the seat type. The alteration of the screen surface edge can acknowledge by changing the position and tallness of the spring support. This screen is used for mining, building materials, transportation, energy, chemical industry.

The working surface of the roller screen is made out of a progression of moving shafts that masterminded on a level plane, on which there are many screen plates. When working, the fine material goes through the hole between the roller or the screen plate. In this way, enormous squares of materials are driven by rollers, moving to the closures and releasing from the outlets. Roller screens are usually widely used in the conventional coal industry.

High frequency vibrating screen is likewise called a high-frequency screen for short. High frequency vibrating screen is made out of exciter, screen outline, supporting, suspension spring and screen, and so on. This type of vibrating screen is the most significant screening machine in the mineral preparing industry, which is reasonable for totally wet or dry crude materials.

Rotary vibrating screen principally utilize for the grouping of materials with high screening effectiveness and fine screening precision. It features a completely shut structure, no flying powder, no spillage of fluid, no obstructing of work, programmed release, no material stockpiling in the machine, no dead point of matrix structure, expanded screen territory, etc. Any molecule, powder, and bodily fluid can screen inside its specific range. The machine usually used for characterization, arrangement, and filtration in nourishment, substance, metal, mining, and some other ventures.

Horizontal screen has the benefits of both slanted screen and straight vibrating screen. The machine has the highlights of good screen penetrability, enormous handling limit, and small installed height. The establishment point of the regular vibrating screen is 15-30, while the establishment of a flat screen is corresponding to the ground, or somewhat slanted 0-5.

Heavy inclined screen can apply to the treatment of debris from the quarry, mine, and building destruction. It can also utilize in the treatment of topsoil, the reusing of development materials, the screening of rock, the screening of gravel and aggregates, etc.

Grizzly screen regularly utilizes for pre-screening before coarse and medium pulverizing of materials. The work size is by and large>50mm, yet some of the time <25mm. This machines productivity is low, but screen efficiency is not that high. Also, quite often, the mesh tends to get a block.

The banana screen has a screen plate with various areas and diverse plunge edges. The longitudinal segment is a broken line, while the entire screen resembles a banana shape. The banana screen is, for the most part, appropriate for the arrangement of huge and medium-sized materials with high substance of fine particles. It can likewise utilize for drying out and demoralization.

While you picking vibrating screens, the material qualities should consider, including the substance of material particles under the screen, the substance of troublesome screen particles, material dampness, the shape and explicit gravity of the material, and the substance of clay. Professional vibrating screens makers could give serious vibrating screen value, assorted variety redid vibrating screen models, auspicious after-deals administration, save parts, and can keep on offering types of assistance for clients entire creation circle.

mev screener - midwestern industries, inc

The high-frequency screens manufactured by Midwestern can be utilized in many screening applications from rugged quarry and rock sizing to sand and gravel processing and high volume fine mesh screening. With a variety of sizes and screening decks, the versatile MEV Screener can fit numerous applications.

The MEV High-Frequency Screener is a rectangular screener that utilizes an elliptical motion to convey material across itsscreening surface. Available in sizes three-foot by five-foot (3 x 5), four-foot by eight-foot (4 x 8), and five-foot by ten-foot (5 x 10) with the availability of one to five screening decks gives the MEV Screener the versatility to meet your screening needs.

The MEV Screener is designed to retain material at the feed end for a longer period of time and then gently slops the material near the discharge end, assisting itoff the screening deck and into production. This is achieved by the screeners unique parallel-arc configuration. Crossbars support the end-tensioned screens tocreate a flat screening surface, thus maximizing the screening area.

The end-tensioned screens used in the high-frequency screener simplify changing screen panels. End-tensioning permits the use of square-opening and slotted screens and is accurately maintained by a spring-loaded drawbar. Users can make screen changes in 1015 minutes.

Midwesterns commitment to providing our customers with outstanding screening products continues with our full line of replacement rectangular screens. Our screens are manufactured to fit all makes and models of screeners.

fixing vexing vibrations | motor

The first step in diagnosing a customers concern is to understand exactly what concerns the customer. Since most people arent very knowledgeable about the inner workings of their vehicle, they sometimes find it hard to describe its latest coughs and hiccups to their technician. This is most true when it comes to noises and vibrations. Im sure youve experienced a customer shaking both fists at chest level, giving the universal sign for a steering wheel vibration, or doing the slight bent-knee bounce, emulating a vibration in the seat. Some drivers might choose to forgo the theatrics and insist that you experience the concern on a road test.

These symptoms fall into the category of noise, vibration, harshness (NVH) concerns. Sometimes the solution to an NVH issue is as simple as addressing the customers perception of a normal vehicle characteristic. The driver might feel that if his 1999 Buick didnt behave in this manner, then his 2010 Nissan shouldnt either.

The vibrations we diagnose on cars and trucks are forced vibrations, which means that the vibration occurs only while the force thats initiating the vibration is present. For example, a vibration caused by a tire will stop as soon as the tire stops spinning. Forced vibrations are tricky because the object the driver feels vibrating is never the origin of the vibration, and is often two or three components removed from the actual cause of the vibration.

Each individual component in a vehicle has a frequency at which it tends to vibrate, depending on the components mass, size and composition. The term frequency of vibration means just thathow frequently the vibration occurs. Frequency is measured in hertz (Hz), which is a measurement of cycles per second. So a frequency of 20Hz means that the component being measured is vibrating 20 times per second. Hz can be converted to rpm by multiplying it by 60, or rpm to Hz by dividing it by 60. The frequency that causes a particular component to vibrate is called its point of resonance.

When a manufacturer designs a vehicle, it attempts to build it so the point of resonance of each component does not equal the frequency of any naturally occurring vibrations. If the vehicles occupants dont feel the vibration, it doesn't exist. This is why we see dampers hanging on exhaust systems, engine mounts, differentials and almost anywhere. These weights change the mass, size and composition of a component, changing its point of resonance to a value outside the frequency range of any naturally occurring vibrations.

If a front tire has a high spot, the vibration is caused by radial runout, which means that the tire is rotating out of its normal range in an up & down direction. If the tire oscillates side to side due to a bent rim, the vibration is caused by lateral runout. In either case, the driver would be complaining of a vibration in the steering wheel, although the steering wheel is not the cause of the vibration. The vibration from the tire is being transferred through the steering rack, along the steering shaft, into the steering column, and is presented to the driver at the steering wheel. In this example, the tire is the originator of the vibration, the steering rack, shaft and column are conductors and the steering wheel is the reactor. The route that the vibration takes is called the transfer path.

Lets say that the tire with the high spot is spinning at 900 rpm during the vibration event. If we do the math and divide 900 by 60, we get 15 revolutions per second, or 15Hz. Since the high spot comes around 15 times per second, the steering wheel would be vibrating at 15Hz. So the tire is producing a first-order vibration of 15Hz.

A first-order vibration is when a revolving component vibrates once every cycle, a second-order vibration is when it vibrates twice in a cycle. Third- and fourth-order vibrations are rare but do happen. A tire with two high spots turning at 900 rpm, or 15Hz, causes a second-order vibration, at 30Hz.

How do you determine the Hz value of a vibration? The best way is with an electronic vibration analyzer (EVA). They work great but are very expensivea couple of thousand dollars for a good one. They usually come with software that enables you to get the frequency of everything that spins in a vehicle just by entering the application. Since this is a lot of money to spend for something that might not be used that often, theres a more economical solution. After all, why buy a snowblower when a shovel will do?

There are numerous free smartphone apps that use the accelerometer in your phone to determine a vibration frequency and convert it to Hz. A couple of the better apps are VibSensor and Mobile Vibration Analyzer. The one I prefer is Vibration Isolator Pro by Mecanocaucho. Its best feature is that you dont need to watch the screen during testing. You can set it down on a vibrating component, it will evaluate the vibration for about five seconds, then show you the amplitude and frequency of the vibration in Hz.

During the road test you need to determine the conditions at which the vibration occurs, and where in the vehicle the vibration is felt. Note the speed and engine rpm during the vibration event, and if the vibration is still present at the same rpm when the vehicle is stopped. Its also important to note the gear that the transmission is in, and whether the vibration is affected by braking, turning or road conditions. Be aware of unusual noises, as noise and vibration often collaborate to create an NVH concern. For example, its not uncommon for a rusted universal joint to produce a high-pitched squeaking sound as well as a vibration. Be sure to record the frequency of the vibration. All of this information will be valuable during your visual inspection.

I cannot overemphasize the importance of the visual inspection. A good visual inspection is the most important step in all automotive diagnoses. In this case, the direction your visual inspection takes will depend on your notes from the road test.

If the road test reveals that the vibration occurs only while the vehicle is moving, your visual inspection should include checking the drive-shaft and tires for damage. I recently serviced a 2002 Ford F-150 with a high-frequency vibration that started at about 35 mph. The visual inspection revealed dents in the rear of the driveshaft caused by the shaft being clamped in a vise during a universal joint replacement. Also check the driveshaft for missing balance weights. During a close inspection you should be able to see witness marks on the shaft where the weights used to be. If you suspect a driveshaft vibration, remove the shaft during your visual inspection so you can properly check the universal joints for looseness or seizing. Check for cracks and exposed nylon cords in the rubber couplers that are sometimes used in place of universal joints.

Be sure to spin all the tires by hand while checking for lateral or radial runout. Check for bubbles and chopped-up treads, and check all around the vehicle for missing or damaged dampers or rubber exhaust hangers.

If the visual inspection fails to identify the cause of the vibration, we can zero in on the originator by matching the frequency value from the road test to a spinning component on the vehicle. But first we need to know the frequency that components are spinning at the time of the vibration event.

We diagnosed a rear-wheel-drive SUV with an 8Hz vibration in the drivers seat at about 54 mph. The vibration could also be felt on various surfaces inside the vehicle, but not in the steering wheel. We took the frequency reading from the top of the center console. At the time of the vibration, the transmission was in 5th gear.

By hooking up a scanner and monitoring the output shaft speed sensor (OSS), we determined that the speed of the driveshaft, which spins at the same speed as the output shaft, was 1771 rpm at 54 mph. When we divide this value by 60, we get 30Hz, a bit faster than the 8Hz vibration we recorded on the road test. Next, we needed to know the speed of the wheels during the vibration.

The rear differential ratio of the SUV was 3.73:1. Differential ratios can be found in the service manual and quite often on a tag attached to the differential housing. This means that the driveshaft makes 3.73 turns for every one turn of the wheels. By dividing the 1771 rpm of the driveshaft by the axle ratio of 3.73, we learned that the wheels were turning at 475 rpm, or 8Hz, at the time of the vibrationthe same frequency we recorded during the road test. Since we didnt feel the vibration in the steering wheel, its safe to say that a rear tire was the cause of the vibration.

Driveshaft speed can also be determined by monitoring transmission input shaft speed using the input shaft speed sensor (ISS) or the turbine speed sensor (TSS) parameter. Dividing the ISS rpm value by the transmission gear ratio will give you OSS speed. The ISS value on the SUV during the vibration event was 1541 rpm, and the gear ratio of the transmission in 5th gear was .87:1. Dividing 1541 by .87 equals the OSS speed of 1771 rpm.

Its not a good idea to use engine rpm to determine ISS speed because of torque converter slippage. When the SUV was showing an ISS value of 1541 rpm, the engine rpm was 1647a torque converter slippage of 106 rpm. So unless youre diagnosing a vibration on a manual transmission vehicle, dont use engine rpm to determine ISS speed.

You can use the same formula for front-wheel-drive vehicles, but since the differential is located inside the transmission, the halfshafts turn at the same speed as the wheels and generate a vibration of the same frequency. The front differentials on 4WD vehicles use the same gear ratio as the rear differential, so the front driveshaft turns at the same speed as the rear driveshaft.

The lesson of the driveline vibration story is that there are two kinds of driveline vibrations low-speed and high-speed. Low-speed vibrations (below 45 mph) are most likely caused by a driveshaft, because the shaft spins fast at low speeds. High-speed vibrations (over 45 mph) are usually caused by a tire or a halfshaft, because higher speeds are needed to get the frequency up to the Hz and amplitude necessary for the vibration to be noticed. Youll find that after youve diagnosed several driveline vibrations, youll start to get a feel for frequency, and what the most likely cause of a vibration would be, without using an analyzer.

Not all vibrations occur while cruising down the highway; some are also present at idle. The most common cause of vibration complaints at idle is driveability problems. Be sure there arent any driveability or base engine concerns before diagnosing an engine vibration, then look at the engine mounts.

A 2008 Ford Focus came into our shop with a nasty high-frequency vibration with the engine at idle, trans in gear. A visual inspection revealed a stone lodged behind the roll restrictor mount, which allowed natural engine vibration to be transferred directly to the body. We performed a stonectomy and the issue was resolved.

Inspect for broken, cracked or separated engine mounts. Engine mounts are designed to absorb the natural vibration of the engine, so any small defect in a mount can produce a vibration whose frequency matches the point of resonance of a component. This is a good example of a vibration not being caused by an out-of-balance originator, but by a faulty dampening component.

You can use engine rpm during the vibration event to determine the Hz at which the engine is spinning. If the vibration frequency is the same as engine speed, then the originator can be narrowed down to the crankshaft damper, torque converter, clutch, flexplate or flywheel. An out-of-balance engine is a possible cause but is highly unlikely in an engine that just developed the issue and isnt knocking like an old tractor.

Carefully inspect the crankshaft damper. Most crankshaft pulleys are mounted to the damper hub on rubber, and this rubber can weasel its way out and cause a significant vibration. Listen closely to the bellhousing with the engine running; most flexplate or torque converter vibrations are accompanied by a sound, as something had to give for the component to start to vibrate all of sudden. If the vehicle is a stick shift, see if the vibration changes while engaging and disengaging the clutch, or if you feel it in the clutch pedal.

If youre diagnosing an engine vibration with a frequency thats higher or lower than the speed of the engine, remove the drive belts and see if it vanishes. An accessory pulley thats smaller than the crankshaft pulley will vibrate at a higher frequency than engine speed, and a larger pulley will vibrate at a lower frequency. Air conditioning clutches are a major culprit when it comes to accessory vibration.

A few tips before I close out this discussion. When using a vibration analyzer, whether its a big-bucks EVA or a phone app, always use the Hz value with the highest amplitude. The analyzer will show you numerous readings of different Hz and amplitude vibrations, but the one the customer is feeling is the strongest one. You wont know if the smaller vibrations need to be serviced until you fix the main one. Usually the lighter vibrations disappear when the heaviest vibration is fixed.

When using a smartphone app, take your frequency reading with the phone resting on a solid surface. The center console and the dashboard are good locations. Avoid seats, carpets and door panels, as soft surfaces can yield erroneous results. If youre using an EVA with a clip-on sensor, try the sun visor; visors tend to vibrate right on time.

Theres an old trick for balancing driveshafts using hose clamps. If you suspect an out-of-balance driveshaft, try this: Put the vehicle on a lift and run the rear wheels, noting the intensity of the vibration. Mark the driveshaft about 6 in. from the back end in four locations 90 apart, and number the marks. Place a hose clamp on the shaft so the clamp is on one of the marks and run the vehicle to see if the vibration changes. If the vibration doesnt diminish, move the clamp screw to a different location. When you find the location that decreases the vibration, add a second clamp right alongside the first, with the screw in the same place. If necessary, you can move the second clamp around the shaft at about -in. intervals to tune it in to the spot that yields the best results. Ive used this procedure many times, and it works well.

You may have horror stories of your own about trying to diagnose vibration concerns. I hope this information makes it a little easier the next time a customer complains about his double latte jiggling in the cup holder at 60 mph.

high-frequency hearing loss: what is it and how is it treated?

One of the most common types of hearing loss is known as high-frequency hearing loss. This means high-pitched sounds are harder to hear. It can affect anyone of any age, but is common in older adults with age-related hearing loss, as well as people exposed to loud noises.

When listening to people speak,you may struggle to hear certainconsonants(such as s, h or f), whichare spoken at a higher pitch. As a result, speech may sound muffled, especially when you're using the telephone, watching television,or in noisy situations. People with this type of hearing loss often say they feel like they can hear, but not understand.

Diagnosis ofhigh-frequency hearing loss is made aftera hearing test in a sound-treated booth at a hearing clinic. A hearing instrument specialist or audiologist usually will conduct the test. The results are plotted onanaudiogram. If a person has high-frequencyhearing loss, the audiogram will showa slope to the right, indicating a person has trouble hearing frequencies between 2,000 and 8,000 Hz.

A person may have mild, moderate, moderately severe, severe or profound hearing loss. (See degrees of hearing loss to learn hearing loss severity is measured.) In the example below, the person has moderately severe high-frequency hearing loss that is slightly worse in the right ear.

High-frequency hearing loss occurs when the tiny hair-like sensory hearing cells in your cochlea (inner ear) are damaged. These hair cells, known as stereocilia,are responsible for translating the sounds your ears collect into electrical impulses, which your brain eventually interprets as recognizable sound.

Age-related hearing lossis called presbycusis. Because this is a slow process thatusually affects both ears equally, its often difficult to notice. One of the first signs is difficultyunderstanding speech in noisy environments.

Millions of Americans have hearing damage due to noise-induced hearing loss. The damage can occur as the result of a one-time, loud exposure to noise, such as a gunshot or explosion, or can occur over time with constant exposure to noise louder than 85 decibels.

Some types of drugs are ototoxic, meaning they are harmful to your hearing health. Some of the more common ototoxic drugs include salicylates (aspirin) in large quantities, drugs used in chemotherapy treatments and aminoglycoside antibiotics.

Menieres disease, which affects the inner ear, often occurs between the ages of 30-50 and may include fluctuating hearing loss, tinnitus and vertigo or intense dizziness. In severe cases, though,it typically causes low-frequency hearing loss.

Typically, thebest type of hearing aidfor high-frequency hearing loss is whats known as a receiver in the ear (RITE) with adome that sits in the ear canal. This style has an open fit so it doesn't muffle the low-frequency sounds that youstill hear naturally.It can be programmed to amplify only the frequencies you struggle to hear.

While some people want to wear devices that are invisible (known as invisible-in-the-canal or completely in the canalhearing aids), they often dont work well for this type of hearing loss, because they block low-frequency sounds.

It's important to address high-frequency hearing loss as its effects extend far beyond struggling to hear. When children have high-frequency hearing loss, it can impede speech and language development, affecting their ability to excel in school. In older adults, untreated hearing loss is associated with a higher risk of cognitive decline, social isolation, depression and injury-causing falls.

High-frequency hearing loss isnt reversible, but in some cases, it is preventable. One of the best prevention techniques is to protect your hearing against exposure to noiseespecially noise louder than 85 decibels. Keep the volume turned down on your personal electronic devices and wear hearing protection whenever you anticipate being in a noisy environment, such as at the shooting range, when riding snowmobiles, or when attending a live concert or sporting event.

Inexpensive ear plugs are available at the local drugstore for occasional use. If you regularly engage in very noisy hobbies, consider investing in specialized hearing protection such as noise-cancelling headphones or custom-made earmolds, which can be purchased through many hearing healthcare professionals.

If you suspect you have hearing loss, use our online directory of consumer-reviewed hearing clinics to find hearing aid centers near you and make an appointment to get your hearing tested. Research indicates most hearing aid wearers are satisfied with their hearing devices and enjoy a richer quality of life than those who decide not to seek treatment.

Joy Victory has extensive experience editing consumer health information. Her training in particular has focused on how to best communicate evidence-based medical guidelines and clinical trial resultsto the public.She strives to make health content accurate, accessible and engaging to the public. Read more about Joy.

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