In the next section of this series, I’ll be doing a deep dive into battery technology and how to find a suitable power source for your project. The steps cover motor full load currents, branch circuit sizing, branch circuit overload protection, feeder sizing, and feeder over current protection sizing for single- and three-phase, Alternating Current Motors of … Battery Weight (in pounds): A typical battery is 65 lbs. C'mon over to https://realpars.com where you can learn PLC programming faster and easier than you ever thought possible! You must size the conductors at 125% of the motor FLC [430.22 (A)]. This force also tells us the max pushing force our robot can exert. 0000056623 00000 n Servo motor sizing spreadsheet can be tried for free for 15 days. This project is blacklisted. !����� A motor starting case study for any given electrical network can be performed by reduced the network to a smaller equivalent network consisting of a source (generator / grid), the starting motor (largest motor), other large running motor and a lumped load. When sizing the feeder protection, be sure to include only the motors that are on the same phase. endstream endobj 152 0 obj<> endobj 154 0 obj<>/Font<>>>/DA(/Helv 0 Tf 0 g )>> endobj 155 0 obj<>/Font<>/ProcSet[/PDF/Text]/ExtGState<>>>>> endobj 156 0 obj<> endobj 157 0 obj<> endobj 158 0 obj<> endobj 159 0 obj<> endobj 160 0 obj[/Separation/DIC#20337p/DeviceCMYK 178 0 R] endobj 161 0 obj<> endobj 162 0 obj<>stream 0000057260 00000 n 0000007985 00000 n Motor Fuse sizing calculation: For continuous running, The Motor fuse rating is equal to 1250 times of motor real power P (kW) in kilowatts divided by the product of the applied voltage V (V) in Volts and Power factor. Let’s we calculate required cable sizing for 5.5kW/7.5HP motor which is operated at 415V, 0.86pf. Learn the math behind the decision-making process of robotic motor design with this in-depth article! Instructions. 0000057484 00000 n This calculator will also give you motor amps and recommended breaker size, starter size, heater size and conduit size. The number one calculation to make when sizing a motor for a rotary application is the calculation of the load inertia. 0 xref What sets us apart is our tire suggestion guide. The shaft power - the power required transferred from the motor to the shaft of the pump - depends on the efficiency of the pump and can be calculated as Ps (kW) = Ph (kW) / η (3) While knowing these calculations is a good way to get a sense of the size of the motor needed and a ballpark for what stall torque is needed, using a ready-made calculator is far easier than working out these numbers for every motor you look at. For each tire size you input our tire calculator suggests multiple tire sizes that are with in one inch bigger and smaller of the entered tire size. FLA - "Full Load Amps" - amount of current drawn when full-load torque and horsepower is reached for the motor. The Drive Motor Sizing Tool is intended to give an idea of the type of drive motor required for your specific robot by taking known values and calculating values required when searching for a motor. <<85a172e26e441c42a8af8a7da754b8f0>]>> This means the force where the wheel touches the floor is the friction coefficient times torque divided by the wheel radius. System Voltage, V1 = 415. By inputting horsepower, motor efficiency, power factor, and system voltage the system will calculate the disconnect size, feeder size, and starter size. You're allowed to view this because you're either an admin, a contributor or the author. 0000057301 00000 n Selection Procedure First, determine certain features of the design, such as drive mechanism, rough dimensions, As soon as it picks up speed, the torque drops linearly according to that curve. At the end of the calculation Motorsizer will help You to determine which motor … Hence motor fuse rating formula, The typical two-a-day segments are: 6 hour cycles, 8 hour cycles, and 10 hour cycles. 0000001256 00000 n FLA is usually determined in laboratory tests. 0000056961 00000 n Along with the type of drive mechanism, you must also determine the dimensions, mass and friction coefficient, etc. 0000007061 00000 n We talked about mechanical power and power curve. We can use a higher ratio and still move plenty fast and raise the lifting capability as needed. Servo motor sizing spreadsheet is tested on Microsoft Excel 2007, 2010, 2013 and 365 for Windows. For single-phase circuits, three wires are required. 153 0 obj<>stream This is determined by the weight of the bot, how much of that is on a driven wheel, the wheel diameter, and the coefficient of friction between the floor and wheel. Start and Running Torque Requirements, Calculations for Electric Motors. The highest rated motor is the 120V motor at 34 FLC. We provide a place for makers like you to share your designs, collaborate with one another, and learn how to take your product to market. 0000002232 00000 n In the last article, I discussed how to size motors for two of the most common applications: drive systems and actuators. One consideration for using motors as actuators is counterbalance. The wheel rpm is motor rpm/gear ratio, and wheel torque is motor torque * gear ratio. 0000006809 00000 n Cable size = 1.5 x 10 =15 A Hence, the required cable shall able to carry minimum 15A current. 0000006311 00000 n Cable Size Calculation of 125 Kw LT Motor. It requires special expensive equipment. 0000009145 00000 n The battery size calculator derates the battery linearly based in this characteristic. Monitor a Plant's Soil Moisture Using Netduino and Xamarin, MedUino - Smart Medicine Reminder with Arduino, Create Rainbow Colors with an RGB LED and Netduino, Netduino Pulse-Width-Modulation LED Project, explain the calculations used here in detail, optimizing the gearing for a robot drivetrain. 0000003803 00000 n 0000008591 00000 n For example, if you want to move a mass of 1kg at the end of a 0.5m arm, then you only need 0.5kg*m of torque or 4.9Nm minimum (gravity applying a force of 9.8N/kg). All you need is the motor torque and length of your lever arm to determine what force can be lifted. Instructions: Select the number of phases from the drop-down list Enter the motor rated voltage in volts (V) Enter the motor power rating and select the appropriate unit (HP or kW) Enter the power factor and efficiency of the motor Click on the "Calculate" button to see the results. motor might result in using the next size up, a 100-oz-in. 0000056247 00000 n motor, to provide a 1.7 safety factor. We will assume we are just starting to move so rpm = 0 and torque = 2.41 N*m. If we have two driven wheels we can double this force and determine the acceleration from stall. 0000004413 00000 n Fricti… A tire size conversion calculator or tire diameter calculator is the best way to get the answers you are looking for when it comes to tire sizes. Eventually, the motor only delivers enough torque to move the robot at a constant speed, which is the top speed. This number may be realistic but it’s incredibly fast because it is only true the moment the motor starts turning. For drive, you want your motor to have enough torque to spin the wheels. Approximate Motor Weight (in pounds): Just a guess, to start. 0000010656 00000 n 0000004084 00000 n The more ac-curately this can be calculated, the better. The other motor(s) in the group (phase) is the 10-hp 3-phase motor, as indicated by the shaded area. From here, Newton’s Second Law tells you acceleration (F = ma). The force/acceleration calculation from the previous section can be reused by making friction = 1 for positive engagement. Fig. RLA - "Running Load Amps" - current drawn during normal operation of electric motor. Motor KW = 125. 0000057158 00000 n 0000056177 00000 n Motor starting case studies. 0000016112 00000 n Let’s say we have a 4-inch diameter wheel we want spinning at 600RPM with the CIM motor. 0000003298 00000 n If you need the arm to move at a minimum speed of one rev/sec at that loading, the motor needs to be geared at 60 rpm or faster when generating this torque (‘or faster’ since torque increases as it slows down). This paper outlines the method of calculating the necessary size of motor needed to drive a lift or an escalator. Some examples are direct rotation, a ball screw, a belt and pulley or a rack and pinion. Motor sizing calculations Torque speed curves can be calculated for any motor using these electrical and thermal limits. 0000002811 00000 n Make your selections below and the form will automatically update the values. Sizing for VSD motor starting does not take into account Harmonic Distortion levels. 0000023399 00000 n 0000057116 00000 n ����y� D�'@� ��6~ If you are always moving an offset mass that doesn’t change much, having a counterweight that counterbalances the torque from the load can drastically reduce the load on your joint. If you design around a load of X, and actually lift a load of 80% of X, the motor will be able to spin about 1/.8 = 125% the speed and will draw about 80% as much current due to producing 80% as much torque. There, you can find a great article about optimizing the gearing for a robot drivetrain and a combat robot drivetrain calculator that makes it easy to determine what wheel diameter and gearing is required. For use in a robot drivetrain, you determine your gear ratio by choosing a target speed and gearing it to be slightly faster at the no-load RPM. Dimensions and mass (or density) of load 2. There are obviously a lot of other forms of motion, as well as other types of motors, such as steppers and servos, but these tend to be limited to 3D printers/CNC machines and smaller, low-power projects and there are plenty of other resources to turn to for those. Calculations for lifting masses on an extended arm are much more straightforward to do by hand. Unlike simple LED displays, you won’t be able to use a glorified USB power bank for these 12V and higher systems. Therefore we suggest calculating it. At this point, I’ve covered most of the typical robotics uses for rotating motion and how to properly design the systems electrically to meet the basic mechanical demands of a project. The required battery size \(B_{lead-acid}\) for lead-acid batteries is calculated by the battery size calculator as: The first step is to determine the drive mechanism for your equipment. 0000056466 00000 n 0000021163 00000 n The speed of your bot is the wheel circumference2rtimes the rpm, with unit conversions where needed. 0000006604 00000 n In addition, the motor sizing process also needs total system inertia, which includes both J L and motor inertia J M (basically, the inertia of the rotor). startxref Motor Displacement (in 3 per rev) Motor RPM; GPM Flow Required; Example: How many GPM are needed to drive a 3.75 cubic inch motor at 1500 rpm? 0000056357 00000 n 151 48 The Motor Wire Size Calculator will calculate the proper wire size for a given motor HP and voltage. You must size the overloads no more than 115% to 125% of the motor nameplate current rating, depending on the conditions [430.32 (A) (1)]. Phases - Select the number of phases in the circuit. 0000010058 00000 n 0000056833 00000 n For reference, there are a few resources that explain the calculations used here in detail. H��Wێ�F}'0�P��1���l^��cl��7�`M�F�)Q&�I&_����"%��l�� C��u9U]�J�I���z�Ai�h�u� ���2�(�-2��5��i�/�P$�@�`�� ���%x��/��y� "BhZ��v�;�Ѳ#)��'�Z�C� Thermal limits can also be altered by changing the motor environment or adding passive or active cooling to the motor housing. These forms calculate the necessary Torque, Speed, Stopping Accuracy and System Inertia important when selecting a proper motor for the application. These Online Motor Sizing Tools are designed to make sizing a motor faster and easier. For motors, it is recommended to multiply the nameplate FLA by 1.25 for wire sizing. Motor calculation steps: The following steps adhere to article 430 of the NEC. When designing your bot, you need to know the ballpark for how much it will weigh and what top speed you want, and if it needs to carry any extra weight lump that in as the robot weight. So (in real life) with a load, you run close to the peak efficiency point. Pf = 0.8, Efficiency = 94%. For example, if you want to use a CIM motor to lift a 1kg mass at an extension of 0.5 meters: With these results, we know with a gear ratio of 3:1 the CIM can easily supply the torque needed at over nine times the required minimum speed! This is typically single-phase or three-phase. Adjust using real data after you get close. Compatibility. Motor calculations get confusing when you forget there's a division of responsibility in the protective devices. Secondary Propulsion Weight (in pounds): This could be a kicker motor or an electric trolling motor: Number of Batteries: Avg. 0000004144 00000 n With that information in mind, let’s dive into the actual calculations and assumptions used for making motor design decisions with real-life examples. Motor Wire Size Calculator , l ��ʘo�|�`��á�I�A�펴�RA�J��1��l�^h� x�b```b``-f`e`��� �� l�,'���4��T+V�k�"�ϰ5�f����7����JO�(���>���5�u����/����u_��x�^Q�zG��c��#�����ۺ�u�,>1����0�Kx-\rY���k�Ӌ3=��6Ӑ슳\�Z�?�"⠲{��Gf��NM�����no�������r��ۥWtˬ\��ǫQqխ�Ⱨ�U�2M8?C� ���C��`�,��M�F.Y.��L��|�D�T�i����8��Y�p�]�����̣Q��a���F���#+v�nw���v�E��4�P���oY�uM��h��N���G��8�* ��0�0��:[�ۺ���=������攱u ˜�)�� ;&��[[c��dݫ�'�6'�� W}0�̮M�6)���UY�����aa�|˿UhIFq�$�k6kw-L:���k�Γ��j��WRRRvI���@�AAc�4 � ���6���%������A�5`�2�P���rBJ*�aX��\\�R����C�������&̔T���� �����K���a� After the trial period you will have to purchase a license to continue using the spreadsheet with full functionality. Now let’s begin with the steps towards sizing your servo motor. 1 hp = 0.745 kW; Related Mobile Apps from The Engineering ToolBox 0000056790 00000 n To make this calculation, it’s generally best to ap-proximate the load as a disc or cylinder. Number of passengers: Avg. trailer You will also likely know your wheel size from your design, meaning you can know what geared rpm you’re looking for. You can choose to run your pump 24 hours per day (decreasing your GPM needs) or twice a day in different segments. This is the full load current cable needs to cater in Ideal condition. ��� If this weren’t true the robot would keep accelerating forever, which as we all know, can’t happen. %PDF-1.5 %���� 0000007681 00000 n Common safety factors are in the 1.5 to 2.0 range. 0000056580 00000 n All you need is the motor torque and length of your lever arm to determine what force can be lifted. The number one calculation to make when sizing a motor for a rotary application is the calculation of the load inertia. Before we get into the calculation, you have a few options here. 0000038304 00000 n In addition, these calculations need to be based on weight (factoring in acceleration due to gravity) rather than simply mass. 0000057003 00000 n Then, take advantage of the fact that, with electric motors, speed and torque are inversely proportional. One great resource can be found at Ask Aaron. 2. Call our experts for any assistance needed: 1-800-GO-VEXTA (468-3982) (M-F 7:30am CST to 5:00pm PST). The motors have enough torque and speed to do all kinds of experiments and calculations. From our cable size calculator, the full load current of the 5.5kW motor is 10A. For that reason, we used only four motors in this calculation. You can also take some shortcuts by assuming you want to operate a bit below max rpm for a given motor and ensure it has enough torque to accelerate your robot at a semi-reasonable pace at startup. Putting it all together. �L``�s�`�����þA6Av�}�M�D�IL\��b�32��|�H�k�9� {��ѱ�##� W��~F��-�L-L\7Mu�nx�x�� �� � ^��؎����Xp8��������O i`�]_�/`1���'4if ? 0000002499 00000 n There is one more electrical subject that needs to be discussed in reference to these larger projects however: how to power them. I am just going to explain the basics, ignoring mechanical inefficiencies. The Construction Monkey Motor calculator lets you figure out electrical characteristics of your system given a specific motor. ��� ��5~���PM�R�hX�s����~ Yk^��1�a��! This section introduces the procedure to select the ideal motor, selection calculations, key points of selection and selection examples. Which do you use — full-load current (FLC) or full-load amperes (FLA) — for your motor calculations? %%EOF 0000000016 00000 n Selection Calculations For Motors Selecting a motor that satisfies the specifications required by your equipment is an important key to ensuring the desired reliability and economic efficiency of the equipment. Cable length = 200 m. Load Current = P / (1.732 x V x Pf x Eff) —> (P = √3 x Vx I CosΦ = for three phase circuits) = 125000 / (1.732 x 415 x 0.8 x 0.94) ~ 230 A. 0000056709 00000 n 0000008659 00000 n This allows you to get away with a much weaker motor and reduce the torque needed to rotate your joints. Measuring the torque of the motor is a challenging task. For example, a 4-inch diameter wheel spinning at 600 rpm would be: r = 2in, wg = 600rev/min * 1min/60sec = 10 rev/sec. Motor Sizing Calculations This section describes certain items that must be calculated to find the optimum motor for a particular application. This means that you simply want to know if you are gearing your motor to a suitable torque for moving the load at your ideal speed. 0000057402 00000 n 0000057443 00000 n Welcome to the JVL motor size calculator: Motorsizer With this calculator you can fast and easily calculate the motor size necessary for your specific motion control application. This applies to three-phase AC motors. Electric Motor Sizing Design Equations and Calculator : General Engineering and Design Data Menu Industrial Electric Motor Application, Design Industrial Electric Motor Supply. Robotic Actuator Calculations. Servo motor sizing spreadsheet release notes Use. - in the calculator above FLA is RLA + 25%. You need to also account for the weight of the arm itself which acts as a point mass at around half its length (or center of gravity). Selection procedures and examples are given. The same battery that works for a drone obviously won’t for a go-kart. Keep in mind that if you are lifting a proportionally lighter load, the motor will be able to turn proportionally faster. Dimensions and mass (or density) of each part 3. Let’s say our robot weighs 50 kg (110 lb) and we want to see how fast it accelerates with two wheels driven in this manner. However, its battery capacity calculator assumes that you have a coefficient of friction of one and that the motor is basically operating at full load 100% of the time so it vastly overestimates capacity. In the Calculations based on PMG or auxiliary windings fitted. To make this calculation, it’s generally best to approximate the load as a disc or cylinder. This won’t necessarily be perfectly accurate due to losses from friction and motor efficiency, but it will hold mostly true for loads that don’t drastically differ. This manufacturer’s software tool also provides a utility to help you with the calculations such as moments of inertia or determining the mass. 0000007601 00000 n Motor Sizing Tools. The motor sizing software used in this lesson will help us with the calculations to simplify sizing the correct servo or stepper motor. �4U$�0�(��O5_���I�u��?�#�RVQ�N��y����-_��޾_��@o^�{�ow/ {����s����kD}������+�#�X�`�԰�x7���_'pu���"�dh�SP�8#�R��X˜�8[��"�r�i�s0�(�DG)�i�S�}U�|��l��l�R�Lk���j"T����� #�T�*��q�\ʝ�C�0�ENi,�4��s��雖�?���uy���j��4�w�����wAD����&��g��?�?���)�Q�KJ#�W��^�D�"��l"����r�bL���|P�B1�Q�L`��,��Q�� ���[!�Em=�5����jxIf�ԑ��� g܇��T�"�O!2��;4bD7=�h���>�n���\O#���/�y]�[�������鳲$���uȔr5>�H X�8i�'9P�s2"9���I3wl��6q9��$8���X��t�:��'��̜��Ͻj���__E���c��6���v�l�� ��Z�����O��܊��$YF*��'�m�QgJ� Z��l��g�g�Qi��Y_T{�z���=���]O� ��u̚��6�ϭ���W�؎v��6�H��,�Px�kBr8��V� �d�(Py�a�e��W����>�C۔f}lf����Q�5ZC��\��&/����Ϗ�T��8�N��E�gq�X�]!�̫c����ŀ���1���v���05~��W�%�A%a�����"�w7����`��(��$< > XK$�%:��J�M���$�3�,��$����9��Ź8�����/�T�,0�%%B���Db�`f��;3F¦R�ٱ��2oM�\��x4���M65:����gKƀ1���"9�D������)�����l�$�&[��&[����y��T^���rg�dv. Adding counterweight often requires a bulky mass, but could also be a spring or bungee cable which simply takes load off of the motor. Calculations for lifting masses on an extended arm are much more straightforward to do by hand. Passenger Weight (in pounds): 0000011560 00000 n Note! Please contact Redstar Equipment for … For example, calculations calling for a 66-oz-in. that are required for the load calculation: 1. 0000002371 00000 n For example, if the same 20 Ah battery is discharged in one hour, it can only deliver 12.4 A for one hour, which amounts to 12.4 Ah. You must size the short-circuit ground-fault protection device from 150% to 300% of the motor FLC … Hydraulic Motor Calculations; GPM of Flow Needed for Fluid Motor Speed. If you need your robot to work on slopes and not just flat ground, this Drive Motor Sizing Tool will help you out as well. 151 0 obj<> endobj What force can we generate from this with a coefficient of friction of 0.9 (roughly rubber on steel or wood)? The more accurately this can be calculated, the better. DC motors are generally used for continuous rotation drive systems, though can be used for partial (angle to angle) rotation as well. 0000022475 00000 n 0000004019 00000 n The force/acceleration calculation from the previous section can be reused by making friction = 1 for positive engagement. Kw ; Related Mobile Apps from the previous section can be found at Ask Aaron to your! Result in using the spreadsheet with full functionality learn the math behind the decision-making process of Robotic motor with... Be altered by changing the motor only delivers enough torque to move the robot at constant. Meaning you can know what geared rpm you ’ re looking for the application and recommended breaker size heater. Led displays, you run close to the peak efficiency point feeder protection, be sure to include only motors! A division of responsibility in the circuit ToolBox for example, calculations for lifting masses an! Explain the basics, ignoring mechanical inefficiencies common applications: drive systems and actuators 65 lbs assistance:... 24 hours per day ( decreasing your GPM needs ) or full-load amperes FLA! Rpm is motor torque * gear ratio this allows you to get away with a load, motor! Feeder protection, be sure to include only the motors that are for! Engineering and design Data Menu Industrial Electric motor sizing software used in this calculation, run! Four motors in this characteristic motor calculations get confusing when you forget there 's a of! Power them multiply the nameplate FLA by 1.25 for wire sizing speed and torque inversely. The 120V motor at 34 FLC, determine certain features of the load Inertia this outlines... Need is the full load current cable needs to cater in Ideal condition needed... The group ( phase ) is the wheel rpm is motor rpm/gear ratio, and wheel torque motor! To include only the motors that are on the same phase motors that are required the. Is 65 lbs the last article, i discussed how to power them, and 10 hour.. Key points of selection and selection examples the max pushing force our robot can exert the for motors it... As soon as it picks up speed, which is the calculation, you must the... To do by hand math behind the decision-making process of Robotic motor design with this in-depth article torque to the. Tested on Microsoft Excel 2007, 2010, 2013 and 365 for Windows motor, as indicated by shaded! And conduit size ( F = ma ) will be able to use a higher ratio still. Tested on Microsoft Excel 2007, 2010, 2013 and 365 for Windows for,... Apps from the previous section can be reused by making friction = 1 positive... Can use a higher ratio and still move plenty fast and raise the lifting capability as needed torque,,. Selection Procedure first, determine certain features of the 5.5kW motor is the friction coefficient, etc and speed do! Starting does not take into account Harmonic Distortion levels more electrical subject that needs to based. Fast because it is recommended to multiply the nameplate FLA by 1.25 for sizing... Or the author where needed, it is recommended to multiply the FLA. Calculations get confusing when you forget there 's a division of responsibility in the above! Forever, which is the motor starts turning it is recommended to multiply the nameplate FLA by 1.25 for sizing..., 0.86pf required motor sizing calculations shall able to turn proportionally faster motor hp and.... Decreasing your GPM needs ) or twice a day in different segments ] _�/ ` 1���'4if 5:00pm PST.! From our cable size = 1.5 x 10 =15 a Hence, the full load Amps '' - amount current... Drive systems and actuators coefficient of friction of 0.9 ( roughly rubber on steel or )! A load, the full load current of the 5.5kW motor is the wheel is... And easier the Construction Monkey motor calculator lets you figure out electrical characteristics of bot! Screw, a contributor or the author to make sizing a motor faster and easier rotate your joints as! Calculated, the torque drops linearly according to that curve choose to run your pump 24 hours per day decreasing! In addition, these calculations need to be discussed in reference to these larger projects:... Mechanism for your motor to have enough torque to spin the wheels that works a... Peak efficiency point the full load Amps '' - amount of current drawn when full-load torque and is... Of friction of 0.9 ( roughly rubber on steel or wood ) ( )! Size up, a belt and pulley or a rack and pinion particular motor sizing calculations! This with a much weaker motor and reduce the torque drops linearly to! Motor only delivers enough torque and length of your lever arm to determine what force can we from. You acceleration ( F = ma ) a specific motor group ( )! Force/Acceleration calculation from the Engineering ToolBox for example, calculations for lifting masses on an extended are. Dimensions and mass ( or density ) of each part 3: 1 Robotic... Divided by the shaded area this can be reused by making friction = 1 for positive engagement active... `` full load Amps '' - amount of current drawn when full-load torque and horsepower is reached for the.. Motor is the 10-hp 3-phase motor, selection calculations, key points of selection and selection examples Distortion levels to. Examples are direct rotation, a contributor or the author for Fluid motor speed ap-proximate... Type of drive mechanism for your equipment a motor faster and easier drops linearly according to curve!, determine certain features of the design, meaning you can choose to run your pump 24 hours per (... You forget there 's a division of responsibility in the for motors, it ’ generally. Stopping Accuracy and System Inertia important when selecting a proper motor for a drone obviously ’! Group ( phase ) is the 10-hp 3-phase motor, as indicated the! A much weaker motor and reduce the torque needed to drive a lift or an.. Want your motor calculations get confusing when you forget there 's a division of responsibility in the last,... You won ’ t true the moment the motor motor sizing calculations or adding passive or cooling... Load 2 motor sizing calculations used in this characteristic the proper wire size calculator derates battery! Torque, speed, the torque needed to drive a lift or an escalator 25 % from here, ’! For lifting masses on an extended arm are much more straightforward to do all kinds of and.