What is Rpm: Definition and 248 Discussions

Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is the number of turns in one minute. It is a unit of rotational speed or the frequency of rotation around a fixed axis.

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  1. J

    The theory behind sound generation from spinning objects

    I am doing a research project investigating the relation between the rpm of an object and the frequency of the sound it generates. The set up is as follows; I am spinning a fidget spinner with a water pressure kit then recording its rpm and the frequency of the sound it creates from its fast...
  2. may ki

    Looking for a 12VDC motor with low RPM

    I'm looking for a motor that will drive a colorwheel inside a robot. All of the 12v/DC motors I have discovered so far have significantly higher RPMs (3000+) than I require. I would prefer something that runs quietly between 3 and 10 RPM. I looked online and found a few gear motors to try, but...
  3. T

    Power, Rpm, Torque - Horsepower increase for my small engine

    Hello all, the short story is, I am basically trying to get the same ( or a little more) “power” out of a larger lawn mower type gas engine ( vertical shaft) as one of the largest (120 ish cc) chainsaws ( ref the Stihl MS 880 or newer 881 at approx 10-12k rpm and 9 Hp) The parameters are : a...
  4. A

    Electronics Need help sealing my 775DC 30,000 rpm motor shaft

    Hi, I need help finding a way to seal my 775DC 30,000 rpm 5mm motor shaft going into my pump housing I built. This motor will run once a week for up to 5 minutes. The pump with have air and water in it. I will rarely ever be completely filled with water. So, the pump will mainly be pushing...
  5. Datt

    Reducing RPM using gears

    I have a question what is a difference or advantage for using two gears with high gear ratio or using three gears with lower gear ratio.Is there any advantage.
  6. J

    I Reaction moment on I.C. engine when we increase RPM

    Every time when you increase RPM on longitudinal placed internal combustion engine, car shake to side in oposite direction of crankshaft rotation. This is reaction moment for change in RPM of crankshaft/flywheel. How this reaction moment transfer to engine block/car if crankshaft is separated...
  7. Al-Layth

    Calculating the change of a Wind Turbine's RPM due to Airflow as f(t)

    the tldr covers everything I think. I don't expect there will be an analytic solution here lol. but I don't even know where to even begin formulating this problem mathematically. I assume I should find an expression for the initial lift on the blades, multiply by 3 and then model it as a...
  8. M

    Calculating turbine RPM in a pipe with known air velocity and diameter

    Hello, I am trying to calculate the turbine RPM for a turbine in a closed pipe. I know the air velocity and pipe diameter. Can this be done?
  9. EFB

    Calculate new RPM after change in g-force in a centrifuge

    Supposed answer = 0.482n
  10. S

    Investigating Why a Century AC Motor's Label Shows 1625 RPM

    Hi great folk I have a Century AC motor which is ¼ HP, 115 V, 60 HZ This is a Permanent Split Capacitor (PSC) motor It has 4 poles, so the running speed according to the motor equation should be: . Speed = 120x60 / p …………….. Where P = number of poles Therefore RPM = 120 X 60 / 4 = 1800 ...
  11. S

    Homework help : What object rotates at 90 RPM?

  12. SpaceThoughts

    I Changing the RPM of a frictionless spinning wheel in a box

    Imagine a spinning wheel built into a hand size vacuum box. There is no friction between the axe bearings of the wheel and the box. Let's say that the wheel rotates with 60 RPM. Am I right if I assume: 1. The wheel continues to rotate, approximately as if in space. 2. It is not possible to...
  13. M

    I Gearbox Gear ratio: How to get 60 rpm to 3500rpm? help please

    Hello I am trying to achieve 3500 rpm from 60rpm. The gear ratio I have worked out is 58:1. To minimize the size I have divided into 4 levels with the gear ratio of 2:1, 3.1, 3.1, 3,1, which rounds me up to 54:1 ratio is also ideal for me can anyone please help mw find the appropriate solution...
  14. B

    B Calculating Football RPM: Accuracy Guidance

    looking for some guidance on what seems to be an oversimplification of calculating RPM. Using hi speed video (240 frames per second), I can determine that it takes .087 of a second for a thrown football to make its first revolution when coming off the hand of the thrower. Assuming I want to use...
  15. G

    RPM & Gas Mileage: Effects on Overdrive Vehicles

    I was reading a post about the effects of RPM on gas mileage, It was from 2007 so I couldn't reply to it. RPM does make a difference on gas mileage when it comes to overdrives. I had an '82 Buick Riviera with a small block engine with an overdrive and a quadrajet that got 26 MPG on the freeway...
  16. Osnel Jr

    AC RPM and the amount of Reactance

  17. R

    How do we maintain the RPM of turbo pumps in liquid rocket engines?

    How do we maintain the RPM of turbo pumps in liquid rocket engine ? and how do we control it ? and in the case of electric pump fed engine (like rocket labs's rutherford engine) is easy but how we do it for other liquid propellant engines ?
  18. A

    How to determine Wind turbine RPM

    How to determine rpm of rotational body such as wind turbine blades. Is there any relation of input wind velocity with the blade rpm? If the rpm formula in relation to input wind velocity is known then I can choose exact matching rpm for electrical generator for a given power output. As per...
  19. R

    The RPM of Dyson DC04 vacuum motor and more....

    Hello, I have got an integrated motor-fan unit of a Dyson DC04 vacuum. I don't know the motor speed (could not find from the manufacturer) but I guess, it must be well in excess of 10,000 rpm. Here is an image: https://www.espares.co.uk/product/es1562476 Now, I want to fit an axial, blower fan...
  20. P

    Automotive Vehicle Parking Brake Test on a Slope [How Convert to a Flat Ground test?]

    Vehicle Mass : 3 tonnes Manufacturer's instruction is to test vehicle's parking brake effectiveness is to engage parking brake on 30.96 degrees slope. If it holds, it is effective. I do not have 30.96 degrees slope & I want to replicate the same test on flat ground. I was thinking of...
  21. NTL2009

    Automotive Design Factors for ICE Peak HP versus RPM?

    I'm thinking about the large (for the 1960's) farm tractors I drove, that produced lots of low end torque, and max RPM was ~ 1800 ~2200 (from memory). Are there certain design factors to maximize horsepower at these low RPMs, versus a common auto engine that might peak around 5,000-6,000 RPM...
  22. O

    AC Mains Generator -- RPM changes based on load changes

    Hi, Scenario: Given a powerplant is being provided a constant power source - like steam is being produced at a steady rate, so that the generator rotates at a constant speed, and in turn, produces a constant electrical frequency. And, suppose, hypothetically, all the power being used...
  23. U

    B Good equation for calculating RPM of a wheel?

    Hello, I am a programmer and I would need an equation to determine the RPM of a wheel. First I select a point in the wheel. Then I measure the time it takes for the wheel to spin arround once. This would give me the results. What would be a good equation for this?
  24. Quix270

    What would happen to a small DC generator if it is spun at higher rpm?

    What would happen to a dc small generator if it is moved at more rpm that is it designed to? Does it will produce more, less or the same? I have this question since I while. Thank you
  25. Plat

    Turbo pump - vibration and noise at a certain RPM

    I have picked up a used pfeiffer turbomolecular pump and controller for pretty cheap. It runs like a champ, completely smooth and quiet except for when it’s first starting up. As it approaches 5500 rpm, it starts vibrating somewhat and sometimes produces a momentary scraping noise when the...
  26. J

    Automotive Need help to find the shaft RPM

    Hi guy here's an example in the picture for my project. i need to find the shaft rpm to find what size pulley D will be. Pulley B attached with a belt that come from a motor. 17.5 hp 3400 rpm 3 inch pulley if I am right and pulley b is 8.4 inch rpm 1214 torque 76 ft/lbs i think the shaft...
  27. E

    Slowly Rotating Device For a Camera Pan Timelapse

    Hello all! I just discovered PF as I have been searching about a project I have been pondering for a day. The idea is to have a device that I can set my 3lb camera and have the device rotate left-to-right && || right-to-left over the duration of 2 hours for use in a sunset/cloud timelapse...
  28. R

    Calculating generator RPM

    Hello, I have a simple question: What is the timer device in a generator? For instance, in order to get the standard frequency of 50Hz, there should be a rotational speed of 3000 rpm. what device measures and ensures this? Thanks
  29. raclemai

    I need to maximize my RPMs in a single cylinder flywheel

    I am working on a flywheel single-cylinder engine powered by a 40 psi air compressor. My task is to achieve as many RPMs as I can. I have already bored two exhaust ports in the frame as shown in the pictures attached. I've done some 600grit sanding on points of contact, am using lubricant prior...
  30. akaf24

    Selecting a Motor for 600 RPM and 3 HP: Do I Need a Controller?

    Hello, for a project I need to select a motor which can rotate at 600 RPM with 3 HP of power. Do AC motors typically require a controller and drive? For example, I am interested in purchasing this. Do I need to buy an expensive controller just to operate it? How complex is the set up and...
  31. S

    Calculate the additive RPM required for tension control

    In a web tension control system, where feed forward is to be used. A tension set point is desired let's say 20lbs, and a load cell system provides feed back. There will be dead weight on the load cell as the material with no pull sits on top of the load cell system. [Obviously I will need to...
  32. saaaaam

    Calculate RPM given the force of a torsion spring

    Homework Statement I've got a flywheel of Inertia = 0.0019302kg/m^2 (found via solidworks), when a torsion spring is released, a force of 10N acts on the wheel via astring attached 0.065m above and 0.0325m to the right of the wheel's axis at an angle of 40 degrees. Homework Equations What is...
  33. Fizzics

    Low RPM, Very efficient DC motor/Generator, 200w to 1Kw

    Hi I am looking to purchase a Low RPM, Very efficient DC motor/Generator between 200w and 1kw for a low friction fly wheel project which involves powering up a 10kg flywheel to about 50 RPM over say 30 seconds then recovering the energy back through the motor/Generator with minimal losses...
  34. R

    Propellers and weight vs RPM

    Hello all... I have a question about an engine-driven propeller. While a propeller is being spun, the air resists it and the maximum power of the engine will turn at "max rpm" when the drag from the air interacting with the propeller becomes equal to the torque generated by that engine. Now...
  35. A

    Plotting a Power Graph using Torque & RPM

    Hi guys, Sorry if this has been covered before but I have been searching the forum looking for the exact information and have been unable to find it. I am currently carrying out a project to make a Honda GX35 engine suitable for competing in the Shell Eco-Marathon where I will perform...
  36. Z

    Finding the Torque vs RPM curve for a 3-phase AC induction motor

    Dear community, For one of the projects which I am currently working on, I want to quantify my three phase AC induction motor in the following ways: 1. Find Torque vs RPM Curve 2.Find Efficiency vs RPM Curve Now since I don't have the industrial "Torque Sensor" to plot Torque vs RPM curves, I...
  37. A

    Small question regarding a motor-compressor gearbox

    Greetings all I have one question here. There is a centrifugal compressor that is driven by an the electric motor. the speed of the compressor is higher than the speed of the electric motor by using a gearbox with speed increaser. suppose that the motor speed is 3600 rpm and the compressor...
  38. S

    Is the relationship between power, torque and RPM a linear relationship?

    Hi I have a problem dealing with rpm power and torque. I have a motor powering a gearbox which has a 20:1 ratio. The power and rpm are not an issue so i have not looked at those figures but the motor produces 240Nm of torque. Since it is a 20:1 gearbox, i have assumed the torque is 20 times...
  39. Z

    Testing: Choosing the right sensor for RPM

    I have no previous experience collecting RPM data so would like advice from those with previous experience. I need to collect RPM data from my machine and record it's behavior as I apply and remove power. I'll be engaging and disengaging a load. So I'm trying to find out how long it takes for it...
  40. E

    Automotive Understanding the Impact of Rapid RPM Change on Torque

    Hello,I've read somewhere that during launch rapid change of RPM causes an increase in torque?What is the point of this?İs that the reason why cars tend to make tires slip when we try to launch at very high RPM?The extra torque added to engine torque?
  41. blainiac

    Maximum RPM until burst for disk?

    Hello everyone! I was wanting to know if something like this was possible. I read (Wikipedia) that the moment a cylinder will burst is when the hoop stress is equal to the cylinder's tensile strength. It also appears that the thickness of the material doesn't matter. I don't see Young's...
  42. W

    Most efficient alternator RPM

    Hello Wizards! Does permanent magnet alternator efficiency increase with RPM? Would an alternator with small magnets turning at high speed be more efficient than and alternator with large magnets turning at low speed. Frequency of output is not a concern, ( converting to dc ) Thanks for...
  43. Tinokoloski

    B How to calculate rpm of an aeolipile

    Hi! I am making an aeolipile as a school project, and I was wondering if you could calculate the rpm. This is the basic principle of an aeolipile. You should be able to calculate the rotating velocity right? Knowing the mass and ignoring any resistance. But then you'll need the rotating...
  44. P

    How to calculate the maximum RPM of a motor?

    Hello all, Just wondering if there is a mathematical formula that calculates the maximum rpm. If I have a fan that puts out 3 pounds of rotational force at stall speed(completely still) at the end point of a 1.5 ft blade what would be the maximum rpm of this fan with the blade attached. What...
  45. M

    B RPM of gear with a force

    Hey guys I do apologize in advance for any errors or misunderstandings in my question, been that english is not my native language. I was wondering how to calculate the RPM of a gear (or a wheel) applied with a known force. I'm guessing I'm not using the correct terminologies using Google...
  46. P

    Relating propeller thrust, power, and rpm together

    Hi All, I am involved in a research project regarding electric aircraft. I've done a fair bit of research into this but am having trouble keeping all the different parameters and how they affect each other straight in my head. Fundamentally I am putting together a model whose parameters I can...
  47. S

    Checking My Gearbox RPM Calculations for Conveyors

    I am not really buying my calculations of a gearboxes rpm for some conveyor applications. First conveyor has to travel 30 feet in 4.5 minutes with 2" rollers. If I divide 30' by 4.5minutes I get 6.667feet/minute and with a 2" diameter the gearbox should be about a 12:1 ratio. The other is a...
  48. Henry Rufin

    RPM vs power consumption

    hi, i have a study on a plucker machine and it came out that when the rotational speed of the plate is low, the power consumption rate is high and if the rotational speed is high, the pcr is low. what is the possible explanation for that? thanks in advace.
  49. C

    Increasing the Power Output of a Turbine

    I have a hydro turbine spinning at 62.746RPM and it produces 170.195Nm of torque. It generates 1.1183kW but ideally, I would like to step it up to at least 4.5kW. Is this possible using a gearbox and if so how can it be done?
  50. T

    Number of turns vs. wire length affecting voltage in coil

    When winding a coil around a magnetic core, if you wanted to tap the coil such that each half has the same AC voltage output, would you: A) wind each part at the same RPM for the same amount of time, to get the same number of turns for each, or B) wind the second part proportionally less, to...