2021 Astec PTSC 2618VM High Frequency Screen. new. Manufacturer: Astec. Vibrating Screen - Double deck PEP Vari-Vibe® high - frequency screen - 6’ x 18’ top deck and 6’ x 12’ bottom deck high - frequency screen s - Top and bottom deck are driven by eleven (11) hydraulic vibrators (0-4200... Alberta, Canada.All decks are high frequency, driven by electric vibrators operating at 3600 RPM. For optimal screen efficiency and production, variable speed hydraulic vibrators (0-4200 RPM) are available upon request. OPTIONS FOR ALL SCREEN SIZES: Screen Cloth - Various types of screen media are available for multiple applications. high-frequency screener GPS series. process for mining linear vibrating. Contact. Weight: 4,724, 4,330 kg. Opening of the mesh: 0.2 mm. Screening surface: 6.7, 4.3 m². GPS series high frequency linear vibrating screen Out GPS series high - frequency linear vibrating screen is used for dehydration of coal slime and gangue. It uses high ...J&H provides a full range of sizes from 4′ (101.6 mm) wide x 5′ (127.0 mm) long up to 7′ (177.8 mm) x 25′ (635.0 mm) long, designed in 5′ (127.0 mm) length increments. This provides 20 ft² (1.858 m²) to 175 ft² (16.258 m²) of screening surface for all three decks. More importantly, the high frequency vibration generated by our J&H ...Aug 28, 2023 · Many screen manufacturers offer inclined, horizontal, banana, and ultrafine options to best suit the processing requirements. Different types of circulation, such as high-frequency vibration, gyratory motion, and circle-throw vibration, can shift materials in ways that optimize the screening process. Find The Right Screen High Frequency Screen Operation • 38°- 43° operating angle • Maximum stroke of .094”/ 2.38mm • Speed range from 3,600 - 4,200 RPM Rotary Tensioning System Provides quick screen media changes Easy replacement of... • 38°- 43° operating angle • Maximum stroke of .094”/ 2.38mm • Speed range from 3,600 ... There are a few old services that the extension can't screen, like Flash, but overall the extension works much like an ad-blocker for ultrasonic tracking. The researchers plan to post their patch ...China High-frequency Screen manufacturers - Select 2023 high quality High-frequency Screen products in best price from certified Chinese Screen Machinery, Metal Screen suppliers, wholesalers and factory on Made-in-China.com2021 Astec PTSC 2618VM High Frequency Screen. new. Manufacturer: Astec. Vibrating Screen - Double deck PEP Vari-Vibe® high - frequency screen - 6’ x 18’ top deck and 6’ x 12’ bottom deck high - frequency screen s - Top and bottom deck are driven by eleven (11) hydraulic vibrators (0-4200... Alberta, Canada. High Frequency Screen Electric/Hydraulic Vibrators - All high frequency screens decks are driven by variable speed hydraulic vibrators (0-4,200 RPM) for optimal screen efficiency and production. Electric vibrators operating at 3600 RPM are available upon request. Directly-Induced Vibration - Applying high speed vibration (3600 - 4200 RPM) directlyMar 23, 2022 · Generally, a few real-life problems cause screen flashing due to high frequency. People’sPeople’s naked eyes have no flicker feeling for the picture over 60hz, while the design standard of the general LCD screen is basically maintained on this data, so the frequency will not be too high under normal circumstances, but at the same time, the ... TCI High-Frequency Screens have the highest screen capacity in the industry for dry, fine material separation. TCI high frequency screens, commonly referred to as "PEP screens", come in a variety of sizes, frequency levels and configurations. Fine material is best separated with high speed and a small stroke.Mar 23, 2022 · Generally, a few real-life problems cause screen flashing due to high frequency. People’sPeople’s naked eyes have no flicker feeling for the picture over 60hz, while the design standard of the general LCD screen is basically maintained on this data, so the frequency will not be too high under normal circumstances, but at the same time, the ... Shaker Screens, Horizontal and Incline Sizing Screens. SIZING SCREENS, SCALPING SCREENS, DEWATERING SCREENS. SCREENS - Horizontal and Incline. M ine T rader.com 814 701 2111. [email protected]. (3) 7x16 Double Deck Horizontal Screen $17,500.00. 5x14 Tabor Single Deck Horizontal Screen $12,500.00. 8x16 Tabor Double Deck Horizontal Screen $16,500.00.The Multi-Vib high frequency screener is available to screen finer particles due to its unique design. The lineal motion created by the two counter-rotating motors located at the top of the screener provide “lift-and-throw” action and the arc of the screen deck helps convey the material to the discharge chutes. The Multi-Vib high frequency ...2ft x 4ft Dillon 3-Deck Screen Make: Dillon Model: 35.2.4.1 Serial: 2732.81 Type: Inclined Screen Condition: Used, Reported in Fair C ID: 1394030 Quote + Astec 2-Deck High Frequency Screen Vibramech M2-67-27 2-Deck Banana ScreenDec 13, 2017 · Would be nice though if there was a way without adjusting xorg.conf or adding a startup script to make this permanent, since also during boot the screen flickers. Somehow on my recent HP Probook 60.01Hz is the default rate and makes my eyes bleed (screen flickers in the dark areas), whilst using 59.93 (2nd available mode listed by xrandr) doesn't. Our high frequency screens offer producers ideal gradation control from reclaiming fines, decks driven by variable-speed hydraulic vibrators for optimal scre...Aug 4, 2020 · We present a hybrid numerical-asymptotic (HNA) boundary element method (BEM) for high frequency scattering by two-dimensional screens and apertures, whose computational cost to achieve any prescribed accuracy remains bounded with increasing frequency. Our method is a collocation implementation of the high order hp HNA approximation space of Hewett et al. (IMA J Numer Anal 35:1698–1728, 2015 ... High Frequency Screen, Find Details and Price about Screen Horizontal Screen from High Frequency Screen - Nanchang Mineral Systems Co., Ltd.PTSC Plant - 6x18. 6'x18' double deck high frequency screen. VFDs to control vibration speed. 36" feed conveyor. Aggregate spreader to promote material distribution. Fines hopper lined with UHMW for material flow. 50-50 split blending gate with AR liner. Hydraulic lifting legs. Hydraulic screen angle adjustment.Jul 29, 2020 · Diagnosing high-frequency hearing loss. Diagnosis of high-frequency hearing loss is made after a 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 on an audiogram. If a person has high-frequency hearing loss, your audiogram will show a ... Mar 15, 2020 · In contrast to hydrocyclones, there was little use of screens in grinding circuits due to blinding problems and high surface area requirement. However, the advances in high-frequency mechanisms and screen surfaces with very small apertures have overcome those problems to some extent and the interest in screen classification is then renewed. Specificity of the Pennsylvania and high-frequency screens were 97% (95% CI 87-100%) and 49% (95% CI 32-65%) respectively. Current school hearing screens have low sensitivity for detection of ...Multi-deck High Frequency Screen Manufacturers, Factory, Suppliers From China, Welcomes all abroad close friends and retailers to ascertain collaboration with us. We are going to give you with genuine, high-quality and successful company to satisfy your requirements.2ft x 4ft Dillon 3-Deck Screen Make: Dillon Model: 35.2.4.1 Serial: 2732.81 Type: Inclined Screen Condition: Used, Reported in Fair C ID: 1394030 Quote + Astec 2-Deck High Frequency Screen Vibramech M2-67-27 2-Deck Banana Screen In 1951, H. William Derrick Jr. invented the first high-speed screen vibrator. Through this successful innovation, he paved Derrick’s path into the Mining & Industrial market. Derrick continues to develop and manufacture an array of wet and dry, fine particle separation technologies that result in increased product recovery and reduced power ...TCI - HIGH FREQUENCY SCREENS • TCI High-Frequency Screens are engineered to provide the highest production capabilities in the market. Aggressive vibration (3600RPM) applied directly to screen media allows for higher capacity and more efficient sizing, compared with conventional screens • Standard separations range from ½”to 20MHigh Frequency Screen. High-frequency are engineered to provide higher production capacities and more efficient sizing than conventional High-frequency operate with aggressive vibration applied directly to the , which allows for the highest capacity in the market for the removal of fine material, as well as chip sizing, dry-manufactured sand ... Our mobile high frequency screens operate at 3600 RPM and up for maximum screening efficiency and production. These screens offer ideal gradation control for reclaiming fines in both wet and dry applications. Pair that with the flexibility and mobility of the track unit and producers can quickly and easily produce the material they need.TCI - HIGH FREQUENCY SCREENS • TCI High-Frequency Screens are engineered to provide the highest production capabilities in the market. Aggressive vibration (3600RPM) applied directly to screen media allows for higher capacity and more efficient sizing, compared with conventional screens • Standard separations range from ½”to 20MHigh Frequency Wireless, Anchorage, Alaska. 1,711 likes · 78 were here. We repair cell phones! Offering used and new cell phones, iPhone repair, Samsung repairs, gaming conHigh Performer Screen X High Performer Screen. MODELS HPS 26, HPS 36, HPS 48. High frequency linear stroke vibrating motion; Alternative to a gyratory vibrating motion circular screen; Screen box design separate from vibrating unit make it possible to construct box using any material, from carbon steel, stainless steel, specialty steels or even ...High Frequency Screen, Find Details and Price about Screen Horizontal Screen from High Frequency Screen - Nanchang Mineral Systems Co., Ltd. We present a hybrid numerical-asymptotic (HNA) boundary element method (BEM) for high frequency scattering by two-dimensional screens and apertures, whose computational cost to achieve any prescribed accuracy remains bounded with increasing frequency. Our method is a collocation implementation of the high order hp HNA approximation space of Hewett et al. (IMA J Numer Anal 35:1698–1728, 2015 ...High Frequency Screen Operation • 38°- 43° operating angle • Maximum stroke of .094”/ 2.38mm • Speed range from 3,600 - 4,200 RPM Rotary Tensioning System Provides quick screen media changes Easy replacement of... • 38°- 43° operating angle • Maximum stroke of .094”/ 2.38mm • Speed range from 3,600 ...high-frequency screener GPS series. process for mining linear vibrating. Contact. Weight: 4,724, 4,330 kg. Opening of the mesh: 0.2 mm. Screening surface: 6.7, 4.3 m². GPS series high frequency linear vibrating screen Out GPS series high - frequency linear vibrating screen is used for dehydration of coal slime and gangue. It uses high ...Nov 8, 2020 · The effect of moisture varies greatly according to other related conditions, such as the following: (1) size at which separation is to be made; (2) frequency and time length of wet coal runs; (3) wet coal and high proportion of fines; (4) wet coal and peak loads; (5) wet coal and high proportion of clay and shale mud. The Multi-Vib high frequency screener is available to screen finer particles due to its unique design. The lineal motion created by the two counter-rotating motors located at the top of the screener provide “lift-and-throw” action and the arc of the screen deck helps convey the material to the discharge chutes. The Multi-Vib high frequency ...High Performer Screen X High Performer Screen. MODELS HPS 26, HPS 36, HPS 48. High frequency linear stroke vibrating motion; Alternative to a gyratory vibrating motion circular screen; Screen box design separate from vibrating unit make it possible to construct box using any material, from carbon steel, stainless steel, specialty steels or even ...Our high frequency screens offer producers ideal gradation control from reclaiming fines, decks driven by variable-speed hydraulic vibrators for optimal scre...Multi-deck High Frequency Screen Manufacturers, Factory, Suppliers From China, Welcomes all abroad close friends and retailers to ascertain collaboration with us. We are going to give you with genuine, high-quality and successful company to satisfy your requirements.We present a hybrid numerical-asymptotic (HNA) boundary element method (BEM) for high frequency scattering by two-dimensional screens and apertures, whose computational cost to achieve any prescribed accuracy remains bounded with increasing frequency. Our method is a collocation implementation of the high order hp HNA approximation space of Hewett et al. (IMA J Numer Anal 35:1698–1728, 2015 ...The Multi-Vib high frequency screener is available to screen finer particles due to its unique design. The lineal motion created by the two counter-rotating motors located at the top of the screener provide “lift-and-throw” action and the arc of the screen deck helps convey the material to the discharge chutes. The Multi-Vib high frequency ... high-frequency screener GPS series. process for mining linear vibrating. Contact. Weight: 4,724, 4,330 kg. Opening of the mesh: 0.2 mm. Screening surface: 6.7, 4.3 m². GPS series high frequency linear vibrating screen Out GPS series high - frequency linear vibrating screen is used for dehydration of coal slime and gangue. It uses high ...Designed for your specific operation, our Dry Vibrating Screens come in a wide range of sizes ranging from 0.9m to 4.8m wide and up to 11.0m long. They are available in horizontal, multi-slope and inclined versions coupled with single, double and triple deck configurations.Latest China HS Code & tariff for high-frequency-screen - Tariff & duty, regulations & restrictions, landed cost calculator, customs data for high-frequency-screen in ETCN. China customs statistics trade data.Specificity of the Pennsylvania and high-frequency screens were 97% (95% CI 87-100%) and 49% (95% CI 32-65%) respectively. Current school hearing screens have low sensitivity for detection of ...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 more FPS (or refresh rate) you have, the smoother and ...Barkhuysen (2009), Valine et al. (2009), Dundar et al. (2014) and Mainza (2016) presented case studies from plants where the hydrocyclones were replaced by high-frequency fine screens to close the grinding circuit and highlighted the potential of using high-frequency fine screening to improve circuit capacity through sharper separation.The refresh rate of your display refers to how many times per second the display is able to draw a new image. This is measured in Hertz (Hz). For example, if your display has a refresh rate of 144Hz, it is refreshing the image 144 times per second. When paired with the high frame rates produced by a GPU and CPU working together, this can result ... 2021 Astec PTSC 2618VM High Frequency Screen. new. Manufacturer: Astec. Vibrating Screen - Double deck PEP Vari-Vibe® high - frequency screen - 6’ x 18’ top deck and 6’ x 12’ bottom deck high - frequency screen s - Top and bottom deck are driven by eleven (11) hydraulic vibrators (0-4200... Alberta, Canada. Features. High power four-way ScreenArray® design for maximum output, optimal coverage, and minimum distortion. 1400 watt midrange featuring four 8" Differential Drive® transducers. Large format 4" neodymium, damped titanium diaphragm, high frequency compression driver. 1600 watt low frequency section with two 18" SVG low frequency drivers.The plant’s innovative design and size is the first of its kind for the industry, featuring an 8-foot-wide high frequency screen. Astec’s newest PTSC plant is equipped with an 8’ x 18’ (2.4 x 5.5 m) top deck and an 8’ x 12’ (2.4 x 3.7 m) bottom deck. The patent-pending screen design features externally-mounted vibrators at the ends ...TCI - HIGH FREQUENCY SCREENS • TCI High-Frequency Screens are engineered to provide the highest production capabilities in the market. Aggressive vibration (3600RPM) applied directly to screen media allows for higher capacity and more efficient sizing, compared with conventional screens • Standard separations range from ½”to 20M The refresh rate of your display refers to how many times per second the display is able to draw a new image. This is measured in Hertz (Hz). For example, if your display has a refresh rate of 144Hz, it is refreshing the image 144 times per second. When paired with the high frame rates produced by a GPU and CPU working together, this can result ... Our mobile high frequency screens operate at 3600 RPM and up for maximum screening efficiency and production. These screens offer ideal gradation control for reclaiming fines in both wet and dry applications. Pair that with the flexibility and mobility of the track unit and producers can quickly and easily produce the material they need.The most popular screen size is the 6’ x 18’, see the chart below. Also, important to notice the capacity of our 6’ x 24’ screen has extra 72 square ft of screening area which adds capacity, efficiency, and separation. It’s one the largest high frequency screen in the industry. (TCI High Frequency Screen Animation)Portable 6’ x 18’ High Frequency Screen with Feed Hopper Model: QSI-30-1003. Portable structure, hydraulic power for raising frame and for raising screen. Oversize chutes, thru's hopper, adjustable screen angle, electric vibrators. Feed hopper, genset, cross conveyors.Dec 1, 2021 · Selected models are detailed and used to describe a high frequency screen trials database, to help identify the advantages and disadvantages offered by each model. The database chosen was reported by Mabote [6], and was obtained through high frequency screen trials using a real scale Derrick Stack Sizer. The database is composed of sampling ... To change the refresh rate. Select Start > Settings > System > Display > Advanced display . Next to Choose a refresh rate, select the rate you want. The refresh rates that appear depend on your display and what it supports. Select laptops and external displays will support higher refresh rates.High frequency inclined portable screening plant with a built-in feeder. The CRS618HF features a 6’x18′ high frequency incline screen specially engineered for fines material screening and incorporates a built in feed conveyor for easy incorporation into new or existing crushing and screening operations. GET MORE INFORMATION. HIGH FREQUENCY SCREEN<br /> A double deck PEP Vari-Vibe ® high<br /> frequency screen with hydraulic screen<br /> angle adjustment and rotary screen<br /> tensioning system meets different aggregate<br /> application demands with ease.<br /> SUPERIOR FINES REMOVAL<br /> The PEP screen is unmatched in the<br /> industry for fines removal ...Designed for your specific operation, our Dry Vibrating Screens come in a wide range of sizes ranging from 0.9m to 4.8m wide and up to 11.0m long. They are available in horizontal, multi-slope and inclined versions coupled with single, double and triple deck configurations. All decks are high frequency, driven by electric vibrators operating at 3600 RPM. For optimal screen efficiency and production, variable speed hydraulic vibrators (0-4200 RPM) are available upon request. OPTIONS FOR ALL SCREEN SIZES: Screen Cloth - Various types of screen media are available for multiple applications. Mar 7, 2023 · We've tested each of these high refresh rate gaming monitors in this list to see whether their claims stand up and make sure no compromise has been made to post those sky-high refresh rate... High-frequency screen, also known as high-frequency vibrating screen, high-frequency filter screen, has the characteristics of reliable structure, strong excitation force, high screening ...The General Kinematics High-Frequency Screen or Feeder, equipped with patented Structural Springs, is perfect for any midrange powder and bulk processing application. More robust than conventional screens yet more cost-effective than pricey ultrasonic options, this screen or feeder is perfect for anyone looking to increase quality without increasing cost. In addition, GK’s signature Two-Mass ... The plant’s innovative design and size is the first of its kind for the industry, featuring an 8-foot-wide high frequency screen. Astec’s newest PTSC plant is equipped with an 8’ x 18’ (2.4 x 5.5 m) top deck and an 8’ x 12’ (2.4 x 3.7 m) bottom deck. The patent-pending screen design features externally-mounted vibrators at the ends ...Jul 6, 2021 · The 1.5 x .375 product would go to the wash plant. The .375 x 0 would go to a high frequency double deck screen with 1/4-in. on the top deck and .125-in. on the bottom deck. We would size the screen to pass the .125-in. x 0 in the 3/8 x 0 feed to pass the bottom deck and be added to the wash plant feed. China High Frequency Screen manufacturers - Select 2023 high quality High Frequency Screen products in best price from certified Chinese Vibrating Screen, Vibration Screen suppliers, wholesalers and factory on Made-in-China.com The refresh rate of a monitor is the speed (rate) at which the monitor’s image changes (refreshes). The faster the refresh rate, the more times the image can update every second and the smoother ...Vibrating screens are the most important screening machines primarily utilised in the mineral processing industry. They are used to separate slurry feeds containing solid and crushed ores down to approximately 200μm in size, and are applicable to both perfectly wetted and dried feed. H-Screening offers high frequency fine screen - stakck sizer, linear vibrating screens for Selected models are detailed and used to describe a high frequency screen trials database, to help identify the advantages and disadvantages offered by each model. The database chosen was reported by Mabote [6], and was obtained through high frequency screen trials using a real scale Derrick Stack Sizer. The database is composed of sampling ...High Frequency Screen or Feeder. The General Kinematics High-Frequency Screen or Feeder, equipped with patented Structural Springs, is perfect for any midrange powder and bulk processing application. More robust than […] 7.3K views 8 years ago. KPI-JCI and Astec Mobile Screens' high frequency screens are engineered to provide higher production capacities and more efficient sizing when compared to conventional ...China High Frequency Screen manufacturers - Select 2023 high quality High Frequency Screen products in best price from certified Chinese Vibrating Screen, Vibration Screen suppliers, wholesalers and factory on Made-in-China.comBoulder City, Nevada 89005. Phone: (702) 323-7316. Email Seller Video Chat. Astec AMS 3100 Prosizer W/3136 Impact Crusher w/ High Frequency Screen *Remote grizzly control *Bulkhead (to assist with ramp) *Suspended 30" Self Cleaning Magnet *Wireless remote package for r...See More Details. Get Shipping Quotes.High-frequency screen. High frequency-screens usually employ vibration that is transmitted to the screen at an operating speed of 3,000 rpm. Additionally, a burst cycle, reaching 4,500 rpm, is provided to control screen blinding. This type of screen is used for fine-mesh screen-ing, with deck sizes ranging from 3/16 in. to 325 mesh. Circular ...
TCI - HIGH FREQUENCY SCREENS • TCI High-Frequency Screens are engineered to provide the highest production capabilities in the market. Aggressive vibration (3600RPM) applied directly to screen media allows for higher capacity and more efficient sizing, compared with conventional screens • Standard separations range from ½”to 20M. Jobs that pay dollar22 an hour no experience
Our mobile high frequency screens operate at 3600 RPM and up for maximum screening efficiency and production. These screens offer ideal gradation control for reclaiming fines in both wet and dry applications. Pair that with the flexibility and mobility of the track unit and producers can quickly and easily produce the material they need.For Sale: 2016 TCI 6'x18' Double Deck High Frequency Screen. Factory brochure link at bottom of page. General: - Manufacture: TCI. - Screen type: High Frequency, also known as PEP screen. - Aggressive vibration (3600 RPM) applied directly to the screen media for optimal separation. - Support structure with stairs and walkway. 2017 ASTEC PTSC 3618VM, Tandem Axle Portable Screen Plant, *Located i Arlington, TX* PEP Vari-Vibe High Frequency Screen, 36" Conveyor, I-Beam Frame, Manual Operated Support Legs, 120 Gal.... As a family-owned business for nearly a century, Deister Machine Company, Inc., plays an integral part within the aggregate industry. Many of the world's largest producers prefer its high quality line of feeding, scalping and screening equipment. Its products integrate with all components of the production system, while delivering maximum ...China High Frequency Screen manufacturers - Select 2023 high quality High Frequency Screen products in best price from certified Chinese Vibrating Screen, Vibration Screen suppliers, wholesalers and factory on Made-in-China.com For Sale: 2016 TCI 6'x18' Double Deck High Frequency Screen. Factory brochure link at bottom of page. General: - Manufacture: TCI. - Screen type: High Frequency, also known as PEP screen. - Aggressive vibration (3600 RPM) applied directly to the screen media for optimal separation. - Support structure with stairs and walkway. Nov 8, 2020 · The effect of moisture varies greatly according to other related conditions, such as the following: (1) size at which separation is to be made; (2) frequency and time length of wet coal runs; (3) wet coal and high proportion of fines; (4) wet coal and peak loads; (5) wet coal and high proportion of clay and shale mud. We've tested each of these high refresh rate gaming monitors in this list to see whether their claims stand up and make sure no compromise has been made to post those sky-high refresh rate...All high frequency screen decks are driven by variable-speed hydraulic vibrators for optimal screen efficiency and production. Producers save time and money with easy hydraulic screen angle adjustments and our unique rotary tensioning system, which ensures the quickest screen media changes in the market. Find out more.Sep 2, 2022 · Many screen manufacturers offer inclined, horizontal, banana, and ultrafine options to best suit the processing requirements. Different types of circulation, such as high-frequency vibration, gyratory motion, and circle-throw vibration, can shift materials in ways that optimize the screening process. Find The Right Screen Vibratory screen is a rectangular single-, double-, and multi-layer, high-efficiency new screening equipment. Vibrating screen can be divided into inclined and horizontal screen. At present, the screens range in width from 4′-12′ to 8′-32′. The screen size is usually set to 2.5 times its length and width. The width of the sieve ... The BRU Vibrating Screen is designed with durability and ease of use as a central focus. And, by improving performance and throughout, you can enjoy better throughput for your equipment. Usable in most applications, these screens come in a wide range of sizes, from 0.9m to 4.8m wide and up to 11.0m long.The High Frequency screener weighs ±1500kg, for the 1500 x 2500mm screen box. Static vertical is 2 x Weight, or 7350N per point. Dynamic Horizontal is 0.2 x Weight, or 735N per point. ELECTRICAL. All motors should run at the same speed and same direction. The screen is fitted with a variable speed drive, one for each pair of motors. .