{"id":8149,"date":"2026-10-09T06:29:51","date_gmt":"2026-10-09T06:29:51","guid":{"rendered":"https:\/\/potensilift.com\/?p=8149"},"modified":"2026-10-09T06:29:53","modified_gmt":"2026-10-09T06:29:53","slug":"elevator-motor-sizing-calculation-how-to-size-a-traction-motor-step-by-step","status":"publish","type":"post","link":"https:\/\/potensilift.com\/es\/elevator-motor-sizing-calculation-how-to-size-a-traction-motor-step-by-step\/","title":{"rendered":"Elevator Motor Sizing Calculation: How to Size a Traction Motor Step by Step"},"content":{"rendered":"<p>Most\u00a0<strong>elevator motor sizing calculation<\/strong>\u00a0errors are not formula errors. The arithmetic is simple and the same equation appears in every calculator. The errors come from the numbers you put into it, and above all from efficiency. Use the wrong efficiency figure and you can under-size a machine by 60 percent, which is the difference between a lift that runs for twenty years and one that overheats, trips, and gets replaced.<\/p><p>This guide goes from what an elevator motor is, through the formula, to the point where you have a model you can actually order.<\/p><div class=\"wp-block-image\"><figure class=\"aligncenter size-large\"><img fetchpriority=\"high\" decoding=\"async\" width=\"1024\" height=\"683\" src=\"https:\/\/potensilift.com\/wp-content\/uploads\/2026\/10\/gearless-elevator-traction-machine-1024x683.webp\" alt=\"gearless elevator traction machine\" class=\"wp-image-8151\" srcset=\"https:\/\/potensilift.com\/wp-content\/uploads\/2026\/10\/gearless-elevator-traction-machine-1024x683.webp 1024w, https:\/\/potensilift.com\/wp-content\/uploads\/2026\/10\/gearless-elevator-traction-machine-300x200.webp 300w, https:\/\/potensilift.com\/wp-content\/uploads\/2026\/10\/gearless-elevator-traction-machine-768x512.webp 768w, https:\/\/potensilift.com\/wp-content\/uploads\/2026\/10\/gearless-elevator-traction-machine-18x12.webp 18w, https:\/\/potensilift.com\/wp-content\/uploads\/2026\/10\/gearless-elevator-traction-machine-600x400.webp 600w, https:\/\/potensilift.com\/wp-content\/uploads\/2026\/10\/gearless-elevator-traction-machine.webp 1536w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\"><a href=\"https:\/\/potensilift.com\/es\/contact\/\"><em>POTENSI helps you select the right traction machine.<\/em><\/a><\/figcaption><\/figure><\/div><h2 class=\"wp-block-heading\">What an Elevator Motor Is<\/h2><p>An elevator motor is the part of the hoisting machine that produces torque. It does not lift the car directly. It turns a grooved wheel called the&nbsp;<strong>traction sheave<\/strong>, and the rope is held in the sheave grooves by friction. Turning the sheave moves the rope, and the rope moves the car and the counterweight.<\/p><p>In practice you rarely buy a motor on its own. You buy a&nbsp;<strong>m\u00e1quina de tracci\u00f3n<\/strong>, which is the motor, the sheave and the brake assembled as one unit, plus a separate drive and encoder. The distinction matters when you size, because the motor has to match the sheave, the roping and the drive, not just the load.<\/p><p>There are two families in common use:<\/p><ul class=\"wp-block-list\"><li><strong>Traction machines<\/strong>, driven by an electric motor. These cover most passenger and freight lifts, and they split again into geared machines with a gearbox between motor and sheave, and gearless machines that drive the sheave directly.<\/li>\n\n<li><strong>Hydraulic lifts<\/strong>, where a pump and hydraulic ram raise the car. These are usual only for low travel and low speed, and their efficiency numbers are different, so they are outside the scope of this calculation.<\/li><\/ul><p>Modern traction machines almost always use a&nbsp;<strong>permanent-magnet synchronous motor (PMSM)<\/strong>&nbsp;in a gearless arrangement. Removing the gearbox makes the assembly compact enough to mount in the shaft instead of a separate room, and the smaller motor can deliver the same performance, which is why machine-room-less layouts dominate new installations.<\/p><p>The practical consequence for an&nbsp;<strong>elevator motor sizing calculation<\/strong>&nbsp;is that the motor, the sheave, the roping, the drive and the brake are one system. Change the roping and you change what the motor has to do.<\/p><h2 class=\"wp-block-heading\">Why the Motor Is Smaller Than You Expect<\/h2><p>The first surprise for anyone new to an&nbsp;<strong>elevator motor sizing calculation<\/strong>&nbsp;is how small the motor turns out to be. A 1,000 kg passenger lift does not need a motor capable of lifting 1,000 kg, and often not even close.<\/p><p>The reason is the counterweight. The counterweight is normally set to balance the weight of the car plus&nbsp;<strong>40 to 50 percent<\/strong>&nbsp;of the rated load. The car and the counterweight hang on opposite ends of the same ropes, so the two weights largely cancel out. The motor only has to move the difference.<\/p><p>With a 1,000 kg lift and a 50 percent balance, the counterweight offsets the car plus 500 kg. The motor therefore works against an unbalanced mass of about 500 kg, not 1,000 kg. That single fact explains most of the machine&#8217;s apparent size, and it is the reason a light-duty motor can move a heavy car.<\/p><p>It also tells you which condition is worst. Because the counterweight sits in the middle of the range, the hardest case is not a half-full car. It is a fully loaded car going up, or an empty car going down, where the unbalanced mass is at its largest.<\/p><h2 class=\"wp-block-heading\">The Elevator Motor Sizing Calculation in One Line<\/h2><p>En&nbsp;<strong>elevator motor power calculation<\/strong>&nbsp;for a counterbalanced traction lift reduces to a single equation:<\/p><p>P=m\u00d7(1\u2212b)\u00d7<em>g<\/em>\u00d7<em>v<\/em>\/<em>\u03b7<\/em>\u200b<\/p><figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Symbol<\/th><th>Significado<\/th><th>Notas<\/th><\/tr><\/thead><tbody><tr><td><em>P<\/em><\/td><td>Motor power<\/td><td>The result, in watts; divide by 1,000 for kW<\/td><\/tr><tr><td><em>m<\/em><\/td><td>Rated load<\/td><td>The car&#8217;s rated load in kg, not the car&#8217;s own weight<\/td><\/tr><tr><td><em>b<\/em><\/td><td>Balancing factor<\/td><td>How much of the rated load the counterweight offsets, normally 0.4 to 0.5<\/td><\/tr><tr><td><em>g<\/em><\/td><td>Gravitational acceleration<\/td><td>9.81 m\/s\u00b2<\/td><\/tr><tr><td><em>v<\/em><\/td><td>Rated speed<\/td><td>The car&#8217;s rated speed in meters per second<\/td><\/tr><tr><td><em>\u03b7<\/em><\/td><td>Overall efficiency<\/td><td>Gearbox efficiency multiplied by shaft efficiency<\/td><\/tr><\/tbody><\/table><\/figure><p>Two things in that formula are easy to get wrong. The numerator uses the&nbsp;<strong>unbalanced<\/strong>&nbsp;mass, which is why the balancing factor appears at all. And the denominator is where almost every under-sized motor comes from, because efficiency is treated as a single number when it is really the product of several losses.<\/p><p>Note what the&nbsp;<strong>elevator motor sizing formula<\/strong>&nbsp;does not contain. Travel height does not appear, because the force needed does not depend on how far the car moves. Speed does appear, and it scales linearly: double the rated speed and you double the power requirement for the same load.<\/p><div class=\"wp-block-image\"><figure class=\"aligncenter size-large\"><img decoding=\"async\" width=\"1024\" height=\"683\" src=\"https:\/\/potensilift.com\/wp-content\/uploads\/2026\/10\/Elevator-Traction-Machine-Supplier-1024x683.jpg\" alt=\"elevator traction machine supplier\" class=\"wp-image-8152\" srcset=\"https:\/\/potensilift.com\/wp-content\/uploads\/2026\/10\/Elevator-Traction-Machine-Supplier-1024x683.jpg 1024w, https:\/\/potensilift.com\/wp-content\/uploads\/2026\/10\/Elevator-Traction-Machine-Supplier-300x200.jpg 300w, https:\/\/potensilift.com\/wp-content\/uploads\/2026\/10\/Elevator-Traction-Machine-Supplier-768x512.jpg 768w, https:\/\/potensilift.com\/wp-content\/uploads\/2026\/10\/Elevator-Traction-Machine-Supplier-18x12.jpg 18w, https:\/\/potensilift.com\/wp-content\/uploads\/2026\/10\/Elevator-Traction-Machine-Supplier-600x400.jpg 600w, https:\/\/potensilift.com\/wp-content\/uploads\/2026\/10\/Elevator-Traction-Machine-Supplier.jpg 1536w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\"><a href=\"https:\/\/potensilift.com\/es\/contact\/\"><em>POTENSI helps you select the right traction machine.<\/em><\/a><\/figcaption><\/figure><\/div><h2 class=\"wp-block-heading\">Step 1 \u2014 Collect the Inputs<\/h2><p>Before calculating, gather these six values. Five come from the specification; the sixth comes from the installation.<\/p><figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Entrada<\/th><th>Where it comes from<\/th><th>Por qu\u00e9 es importante<\/th><\/tr><\/thead><tbody><tr><td>Carga nominal (kg)<\/td><td>Car specification<\/td><td>Sets the unbalanced mass<\/td><\/tr><tr><td>Velocidad nominal (m\/s)<\/td><td>Car specification<\/td><td>Scales power directly<\/td><\/tr><tr><td>Balancing factor<\/td><td>Machine specification, normally 0.4 to 0.5<\/td><td>Decides how much of the load is offset<\/td><\/tr><tr><td>Roping ratio (1:1 or 2:1)<\/td><td>Shaft layout<\/td><td>Changes both speed relationship and losses<\/td><\/tr><tr><td>Guide type (slide or roller)<\/td><td>Shaft layout<\/td><td>Changes shaft efficiency<\/td><\/tr><tr><td>Starts per hour and travel<\/td><td>Traffic study<\/td><td>Decides the duty rating, not the power<\/td><\/tr><\/tbody><\/table><\/figure><p>The first three give you the theoretical power. The last three are what turn that theoretical figure into a machine that survives its working life. Skipping them is the most common way to reach a number that is mathematically correct and practically wrong.<\/p><h2 class=\"wp-block-heading\">Step 2 \u2014 Choose the Balancing Factor<\/h2><p>En&nbsp;<strong>counterweight balancing factor<\/strong>&nbsp;is the share of the rated load the counterweight offsets. A factor of 0.5 means the counterweight balances the car plus half the rated load.<\/p><p>The usual range is&nbsp;<strong>0.4 to 0.5<\/strong>, and 0.5 is the common choice for passenger lifts. The reason is energy rather than peak capability. At 0.5 the average unbalanced mass over a working day is at its lowest, so the motor works least on average. Push the factor up and a heavily loaded car becomes easier to lift, but an empty car becomes harder to bring down, and the average gets worse.<\/p><p>Two practical points:<\/p><ul class=\"wp-block-list\"><li><strong>The counterweight is a fixed weight.<\/strong>\u00a0It cannot follow the load. Whatever factor you choose, the unbalanced mass changes every trip, and your calculation must use the worst case.<\/li>\n\n<li><strong>The worst case is a full car or an empty car<\/strong>, at 0.5. A half-loaded car is the easy case, not the hard one. This is the opposite of what many people assume when they check a design.<\/li><\/ul><h2 class=\"wp-block-heading\">Step 3 \u2014 Get the Efficiency Right<\/h2><p>This is the step that decides whether your&nbsp;<strong>elevator motor sizing calculation<\/strong>&nbsp;produces a machine that lasts.<\/p><p>Overall efficiency is not one number. It is a product:<\/p><p><em>\u03b7<\/em>=<em>\u03b7<\/em><em>A<\/em>\u200b\u00d7<em>\u03b7<\/em><em>A<\/em><em>n<\/em><em>l<\/em>\u200b<\/p><figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>T\u00e9rmino<\/th><th>What it covers<\/th><th>Typical value<\/th><\/tr><\/thead><tbody><tr><td><em>\u03b7<\/em><em>A<\/em>\u200b<\/td><td>Gearbox efficiency<\/td><td>Below 1 for a geared machine;&nbsp;<strong>1 for a gearless machine<\/strong>, because there is no gearbox<\/td><\/tr><tr><td><em>\u03b7<\/em><em>A<\/em><em>n<\/em><em>l<\/em>\u200b<\/td><td>Shaft efficiency: all the losses between the machine and the car<\/td><td>Usually between&nbsp;<strong>0.60 and 0.86<\/strong><\/td><\/tr><\/tbody><\/table><\/figure><p>Shaft efficiency carries the losses in the pulley bearings, the car and counterweight sheaves, the guide rail friction and the rope weight. Published figures from machine manufacturers put it between 60 and 86 percent, and the practical consequence is blunt: some projects need a motor&nbsp;<strong>60 percent larger<\/strong>&nbsp;than the plain calculated figure. That is not a rounding difference.<\/p><p>The values below come from an analysis of shaft efficiency published by Elevator World. If your machine supplier publishes its own recommended figures, use theirs, because they know the machines they build.<\/p><figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Condici\u00f3n<\/th><th>Shaft efficiency<\/th><th>Effect on motor size<\/th><\/tr><\/thead><tbody><tr><td>Slide guide shoes<\/td><td>0.90 to 0.95, average 0.93<\/td><td>The baseline case<\/td><\/tr><tr><td>Roller guide shoes<\/td><td>0.93 to 0.98, average 0.95<\/td><td>Lower loss than slide shoes, so a smaller motor<\/td><\/tr><tr><td>2:1 roping<\/td><td>Lower than 1:1<\/td><td>More pulleys in the system, so more bearing loss<\/td><\/tr><tr><td>L-type car frame<\/td><td>Much lower<\/td><td>Much higher rail friction, so the motor must be larger<\/td><\/tr><tr><td>Heavier car relative to rated load<\/td><td>Inferior<\/td><td>More weight to move for the same payload<\/td><\/tr><\/tbody><\/table><\/figure><p>Use 0.5 as the reference balancing factor and 0.05 as the reference rope weight divided by rated load, which are the conditions those figures are quoted against.<\/p><p>If you take one thing from this article, take this:&nbsp;<strong>a gearless machine removes the gearbox loss but does not remove shaft loss.<\/strong>&nbsp;Gearless does not mean lossless, and treating it that way is the single most common sizing error.<\/p><h2 class=\"wp-block-heading\">Step 4 \u2014 From kW to a Motor You Can Actually Order<\/h2><p>Work the&nbsp;<strong>elevator motor sizing calculation<\/strong>&nbsp;through once, end to end. Take a 1,000 kg lift at 1.5 m\/s, with a balancing factor of 0.5 and an overall efficiency of 0.75.<\/p><p><strong>Unbalanced mass<\/strong><\/p><p>m\u00d7(1\u2212b)=1000\u00d70.5=500\u00a0kg<\/p><p><strong>Mechanical power<\/strong><\/p><p>P=(500\u00d79.81\u00d71.5)\/1000=7.36\u00a0kW<\/p><p><strong>Motor input power<\/strong><\/p><p>Pin=7.36\/0.75=9.81\u00a0kW<\/p><p>You cannot order a 9.81 kW motor, so you move up to the next standard rating and select an&nbsp;<strong>11 kW<\/strong>&nbsp;machine with a drive rated for it. For reference, passenger lift motors commonly fall in the&nbsp;<strong>5 to 15 kW<\/strong>&nbsp;band.<\/p><p><strong>Full-load current<\/strong><\/p><p>If you also need the current for the supply and the cable, use:<\/p><p>I=P\/(\u221a3\u00d7V\u00d7cos\u2061\u03d5\uff09\u200b<\/p><p>At 400 V and a power factor of 0.85, an 11 kW motor draws roughly&nbsp;<strong>18.7 A<\/strong>. Substitute your own supply voltage, because 380 V, 400 V and 415 V all appear in different markets and the current changes accordingly.<\/p><p>One clarification the calculators tend to bury: this current is the&nbsp;<strong>peak draw while the motor is running at rating<\/strong>. It is not the average consumption of the lift. Over a day the average is far lower, because the counterweight offsets most of the load and the lift spends most of its time standing still. Do not size a generator or an energy budget from the full-load current.<\/p><h2 class=\"wp-block-heading\">Step 5 \u2014 Check the Dynamic Case, Not Just the Steady State<\/h2><p>Everything so far gives you the power to move a mass at a constant speed. That is the&nbsp;<strong>steady state<\/strong>&nbsp;check, and on its own it is not enough.<\/p><p>The second check is the&nbsp;<strong>dynamic<\/strong>&nbsp;one: can the motor accelerate the car, the counterweight and the ropes up to rated speed within the acceleration the design calls for? Starting a lift requires more torque than running it, because the motor must first overcome the static friction in the system and then accelerate the whole moving mass.<\/p><p>A machine that passes the steady state check and fails the dynamic one will start slowly, feel sluggish, or trip on overload during every start. Published guidance for lifting and elevating drives suggests selecting a motor with at least&nbsp;<strong>30 percent more torque than the calculated minimum<\/strong>, which is a rule of thumb rather than a standard.<\/p><p>Two cautions:<\/p><ul class=\"wp-block-list\"><li><strong>Calculate with real data.<\/strong>\u00a0An unloaded test tells you almost nothing about acceleration behavior, because the unbalanced mass is different from the design case.<\/li>\n\n<li><strong>Check both directions.<\/strong>\u00a0The worst case for one direction is not the worst case for the other.<\/li><\/ul><h2 class=\"wp-block-heading\">The Parameters on the Nameplate, Decoded<\/h2><p>Once you have a number, the nameplate is what you order against. Each field exists because it constrains the fit.<\/p><figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Par\u00e1metro<\/th><th>What it decides<\/th><\/tr><\/thead><tbody><tr><td>Model or type code<\/td><td>The family identifier. This, not the brand name, is what a supplier can actually match<\/td><\/tr><tr><td>Rated load and rated speed<\/td><td>The machine&#8217;s rating. Both must suit the installation<\/td><\/tr><tr><td>Power, voltage and frequency<\/td><td>Must match the drive and the supply on site<\/td><\/tr><tr><td>Rated current<\/td><td>Feeder and cable sizing<\/td><\/tr><tr><td>Roping ratio and sheave diameter<\/td><td>The transmission ratio and the rope layout<\/td><\/tr><tr><td>Duty rating and starts per hour<\/td><td>Whether the machine can carry the traffic without overheating<\/td><\/tr><tr><td>Tensi\u00f3n de frenado<\/td><td>The brake control circuit<\/td><\/tr><tr><td>Tipo de codificador<\/td><td>The drive&#8217;s feedback input; a machine will not run in closed loop without a match<\/td><\/tr><tr><td>Protection class<\/td><td>Whether the machine suits a machine-room-less shaft or a damp environment<\/td><\/tr><\/tbody><\/table><\/figure><p>If you are replacing a machine rather than sizing a new one, photograph the nameplate before you contact anyone. It answers most of a supplier&#8217;s first questions.<\/p><h2 class=\"wp-block-heading\">Which Type of Motor Are You Sizing<\/h2><p>The type changes the&nbsp;<strong>elevator motor sizing calculation<\/strong>, so decide it first.<\/p><p><strong>Traction or hydraulic.<\/strong>&nbsp;Hydraulic lifts use a pump and ram. Their efficiency figures are different, and the counterweight formula above does not apply. If the installation is hydraulic, this article&#8217;s calculation is the wrong tool.<\/p><p><strong>Geared or gearless.<\/strong>&nbsp;A geared machine has a gearbox between the motor and the sheave, so&nbsp;\u03b7A<em>\u03b7<\/em><em>A<\/em>\u200b&nbsp;is below 1. A gearless machine has none, so&nbsp;\u03b7A<em>\u03b7<\/em><em>A<\/em>\u200b&nbsp;is 1. This is the largest single fork in the efficiency calculation.<\/p><p><strong>Induction or permanent magnet.<\/strong>&nbsp;Modern gearless machines use a permanent-magnet synchronous motor. Compared with earlier AC machines, a PMSM delivers the same performance from a smaller frame, which is what made machine-room-less layouts practical. Studies of lift energy use report that combining a machine-room-less layout, a variable-speed drive and a PMSM motor can cut operational energy substantially compared with older traction systems.<\/p><p>The practical rule: know which family you are in before you calculate, because the efficiency terms differ, and do not borrow a figure from one family to use in another.<\/p><h2 class=\"wp-block-heading\">Duty Cycle and Starts per Hour<\/h2><p>A lift motor does not run continuously. It starts, runs, stops, and waits, hundreds of times a day. Its rating describes what it can do in that pattern, not what it could do running flat out.<\/p><p>No&nbsp;<strong>elevator motor sizing calculation<\/strong>&nbsp;is finished at the power figure. This is why the calculators, including the one that supplies the formula above, end with a caveat rather than a number: the result is a preliminary estimate, and&nbsp;<strong>the final selection is governed by the manufacturer&#8217;s duty cycle and starts-per-hour data<\/strong>. The same car and the same load can call for a different machine in a busy office tower than in a quiet residential block, because the number of starts per hour decides how much heat the motor has to shed.<\/p><p>Two consequences:<\/p><ul class=\"wp-block-list\"><li>A machine that is correct on power can still be wrong on duty. If it is specified for the traffic of a low-rise apartment and installed in a lobby with constant turnover, it will run hot.<\/li>\n\n<li>When you ask a supplier to confirm a selection, give them the starts per hour and the travel distance along with the load and speed. Without those two figures they are estimating.<\/li><\/ul><h2 class=\"wp-block-heading\">The Five Mistakes That Cause an Undersized Motor<\/h2><p>Five errors account for most undersized machines. None of them is an arithmetic mistake; every one is a choice about inputs or checks. That is how an&nbsp;<strong>elevator motor sizing calculation<\/strong>&nbsp;can be right on paper and still lead to the wrong machine.<\/p><ol class=\"wp-block-list\"><li><strong>Treating efficiency as 1.<\/strong>\u00a0This is the most common error and the most expensive. Shaft efficiency alone can be 0.60.<\/li>\n\n<li><strong>Forgetting the 2:1 penalty.<\/strong>\u00a0Extra pulleys mean extra bearing loss, so a 2:1 layout usually needs more motor than the same lift at 1:1.<\/li>\n\n<li><strong>Doing only the steady state check.<\/strong>\u00a0Power at constant speed is not the same as the ability to accelerate.<\/li>\n\n<li><strong>Ignoring duty and starts per hour.<\/strong>\u00a0The power figure is right and the machine still fails, because the traffic is heavier than the rating assumed.<\/li>\n\n<li><strong>Sizing from the car weight instead of the unbalanced load.<\/strong>\u00a0The counterweight already carries most of the weight. Using the gross load produces a motor far larger than necessary and a misleading cost.<\/li><\/ol><h2 class=\"wp-block-heading\">Sizing Checklist<\/h2><p>Work through these in order. Each step feeds the next, and each one is a point where an&nbsp;<strong>elevator motor selection<\/strong>&nbsp;commonly goes wrong.<\/p><ol class=\"wp-block-list\"><li>Confirm the family: traction or hydraulic.<\/li>\n\n<li>Confirm the arrangement: geared or gearless.<\/li>\n\n<li>Record rated load and rated speed from the car specification.<\/li>\n\n<li>Record the balancing factor and confirm it against the counterweight actually fitted.<\/li>\n\n<li>Record the roping ratio and the guide shoe type.<\/li>\n\n<li>Calculate the unbalanced mass.<\/li>\n\n<li>Choose the efficiency figure, splitting gearbox efficiency from shaft efficiency.<\/li>\n\n<li>Calculate mechanical power, then motor input power.<\/li>\n\n<li>Move up to the next standard motor rating.<\/li>\n\n<li>Calculate full-load current from the supply voltage and power factor.<\/li>\n\n<li>Check the dynamic case: can it accelerate to rated speed?<\/li>\n\n<li>Check duty and starts per hour against the intended traffic.<\/li>\n\n<li>Match the drive, encoder and brake voltage before ordering.<\/li><\/ol><h2 class=\"wp-block-heading\">Preguntas frecuentes<\/h2><p><strong>What is the formula for elevator motor power?<\/strong>&nbsp;For a counterbalanced traction lift, mechanical power equals the unbalanced mass multiplied by gravity and by the rated speed, divided by efficiency. The unbalanced mass is the rated load multiplied by one minus the balancing factor.<\/p><p><strong>What is the counterweight balancing factor?<\/strong>&nbsp;It is the share of the rated load that the counterweight offsets. It is normally between 0.4 and 0.5, with 0.5 common for passenger lifts.<\/p><p><strong>Why is the motor power less than the weight of the car and its load?<\/strong>&nbsp;Because the counterweight balances the car plus roughly half the rated load. The car and the counterweight hang on opposite ends of the same ropes, so the motor only moves the difference between them.<\/p><p><strong>Does speed affect motor size?<\/strong>&nbsp;Yes, directly. Power scales linearly with rated speed, so doubling the speed doubles the power requirement for the same load.<\/p><p><strong>What efficiency should I use?<\/strong>&nbsp;Split it. Gearbox efficiency is 1 for a gearless machine and below 1 for a geared one. Shaft efficiency is usually between 0.60 and 0.86 depending on guide shoes, roping and car frame. Use your supplier&#8217;s published figures where they exist.<\/p><p><strong>Can I finish an elevator motor sizing calculation without the supplier&#8217;s data?<\/strong>&nbsp;You can reach a preliminary figure, which is enough to budget and to shortlist. You cannot make the final selection, because the duty cycle and starts-per-hour data decide whether the machine can carry the traffic.<\/p><p><strong>How much power does a typical passenger lift motor need?<\/strong>&nbsp;Passenger lift motors commonly fall between 5 and 15 kW, depending on load and speed. Confirm the figure with the calculation rather than a range, because efficiency and duty can move the result well outside it.<\/p><h2 class=\"wp-block-heading\">The Short Version<\/h2><p>A correct&nbsp;<strong>elevator motor sizing calculation<\/strong>&nbsp;comes down to three things: the unbalanced mass, which the counterweight decides; the rated speed, which scales the result directly; and the efficiency, which is a product of gearbox and shaft losses rather than a single figure. Add the dynamic check for acceleration and the duty check for starts per hour, and you have a selection that will survive real traffic rather than only pass on paper.<\/p><p>If you are sizing a machine or replacing one, send us the rated load, rated speed, roping and the nameplate photograph. We will check the figures against the machine you are considering.<\/p><p><em><a href=\"https:\/\/potensilift.com\/es\/about-us\/\">POTENSI<\/a> supplies elevator traction machines, hoisting equipment and replacement parts for elevators and escalators. See our\u00a0<a href=\"https:\/\/potensilift.com\/es\/piezas-de-ascensores\/elevator-traction-system\/maquina-de-traccion-de-ascensores\/\" target=\"_blank\" rel=\"noreferrer noopener\">Gama de sistemas de tracci\u00f3n para ascensores<\/a>\u00a0o\u00a0<a href=\"https:\/\/potensilift.com\/es\/contact\/\" target=\"_blank\" rel=\"noreferrer noopener\">send us your project details<\/a>.<\/em><\/p><p><\/p>","protected":false},"excerpt":{"rendered":"<p>Most\u00a0elevator motor sizing calculation\u00a0errors are not formula errors. The arithmetic is simple and the same equation appears in every calculator. The errors come from the numbers you put into it, and above all from efficiency. Use the wrong efficiency figure and you can under-size a machine by 60 percent, which is the difference between a [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":8152,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_seopress_titles_title":"Elevator Motor Sizing Calculation: Size a Traction Motor Step by Step","_seopress_titles_desc":"How to size an elevator motor: the power formula, the counterweight balancing factor, the efficiency values that decide the result, and how to check acceleration and duty cycle before you order.","_seopress_robots_index":"","_seopress_robots_follow":"","_seopress_robots_imageindex":"","_seopress_robots_snippet":"","_seopress_robots_primary_cat":"","_seopress_robots_breadcrumbs":"","_seopress_robots_freeze_modified_date":"","_seopress_robots_custom_modified_date":"","_seopress_robots_canonical":"","_seopress_social_fb_title":"","_seopress_social_fb_desc":"","_seopress_social_fb_img":"","_seopress_social_fb_img_attachment_id":0,"_seopress_social_fb_img_width":0,"_seopress_social_fb_img_height":0,"_seopress_social_twitter_title":"","_seopress_social_twitter_desc":"","_seopress_social_twitter_img":"","_seopress_social_twitter_img_attachment_id":0,"_seopress_social_twitter_img_width":0,"_seopress_social_twitter_img_height":0,"_seopress_redirections_value":"","_seopress_redirections_enabled":"","_seopress_redirections_enabled_regex":"","_seopress_redirections_logged_status":"","_seopress_redirections_param":"","_seopress_redirections_type":0,"_seopress_analysis_target_kw":"","footnotes":""},"categories":[175],"tags":[],"class_list":["post-8149","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-industry-news"],"_links":{"self":[{"href":"https:\/\/potensilift.com\/es\/wp-json\/wp\/v2\/posts\/8149"}],"collection":[{"href":"https:\/\/potensilift.com\/es\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/potensilift.com\/es\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/potensilift.com\/es\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/potensilift.com\/es\/wp-json\/wp\/v2\/comments?post=8149"}],"version-history":[{"count":1,"href":"https:\/\/potensilift.com\/es\/wp-json\/wp\/v2\/posts\/8149\/revisions"}],"predecessor-version":[{"id":8153,"href":"https:\/\/potensilift.com\/es\/wp-json\/wp\/v2\/posts\/8149\/revisions\/8153"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/potensilift.com\/es\/wp-json\/wp\/v2\/media\/8152"}],"wp:attachment":[{"href":"https:\/\/potensilift.com\/es\/wp-json\/wp\/v2\/media?parent=8149"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/potensilift.com\/es\/wp-json\/wp\/v2\/categories?post=8149"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/potensilift.com\/es\/wp-json\/wp\/v2\/tags?post=8149"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}