# Questions tagged [motors]

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52k views

### Understanding required torque for a motor lifting a weight

This is a continuation of me trying to understand torque and stepper motors in my other question. I'm trying to understand the torque a motor would be required to generate to lift a small weight, and ...
25k views

### Effective ways to drive a single shaft with multiple motors?

To head off the "why not use a bigger motor" question, I'm a high school mentor for an FTC (First Tech Challenge) robotics team, with a bit of a soft mechanical / hardware background. They're ...
3k views

### What is this small rotating part from a cell phone?

What is this tiny rotating piece of hardware that I found inside my Samsung GE1202? It has E9C written in blue on it.
579 views

### Avoid snapping an electric cable from too much rotation

I recently built the basic construction for a crane out of lightweight material. Basically the head of the crane contains an electric servo motor which spins the head of the crane by pushing itself ...
963 views

### How to calculate Power of motor when used as a generator?

How can you calculate how much power can be generated by a motor when used as a generator (like a motor used in a wind turbine)? Does the power depend on how fast the magnet is rotated? If so, is ...
802 views

I am trying to simulate a winch as a speed-regulated motor that works through a gearbox to lift a mass. The output of the gearbox is a drum, which rotates to accumulate cable. I feel comfortable ...
1k views

### Air compressor that doubles as a pneumatic motor?

I am working on a compressed air energy storage system. The size and weight of the system are heavily constrained; nothing should (ideally) exceed a few pounds. For this reason, I would like to store ...
116 views

### Which is more durable in sandy desert conditions: electric motors or hydraulic pistons?

If we have a tracking system placed in a tough desert environment with occasional sandstorms and temperatures that go as high as 50C, which actuator would be better: a hydraulic piston or an electric ...
155 views

### Under what circumstances would one need or not need an electronic brake for a permanent magnet motor?

My company was asked to design a custom product several years ago. The original requester never bought it, but we've sold several a year through distribution. It's been a small side-line for a while, ...
17k views

### What is Starting Torque?

I'm having a hard time finding an answer from the internet. What does starting torque mean?
1k views

### Why does public transport uses compressed air to open doors instead of electromotors?

System with compressed air seems more expensive and harder to build and integrate neither using simple electromagnetic drives to open public transport doors.
3k views

### What is the use of gears in a device with a fixed gear ratio?

From my understanding, there are two uses of a gearing system: to change the speed of output rotation (trading it with torque), and to change the axis of rotation. Now, in a car, for example, it is ...
960 views

### What would happen if we tried to run a motor in space when it is not attached to anything to provide support to it?

I know that when a motor runs it generates torque and that torque can be used to do useful work. On the other hand, the motor needs strong support that absorbs the reaction torque. In our case let us ...
334 views

### Power and motor current

This is a follow up question to my question here about torque and stepper motors. There Olin explains: Note also that torque isn't the only criterion for a motor. Power is another important one. ...
126 views

### How can I tell if a motor is defective?

I recently bought two 12 V DC motors from Amazon. After I received them today, I tried testing them. One of the two motors run fine but the other motor shows erratic behaviour. It gets very hot within ...
96 views

### How do DC motor parameters scale with motor size?

Consider the following DC motor parameters: Rotor resistance, $R\ [\Omega]$ Motor constant, $k_t\ [\mathrm{V/rpm}]$ Inertia, $I\ [\mathrm{kg\cdot m^2]}$ How do they scale with motor size? Do $R$ and ...
246 views

### How does a windshield wiper work?

Basic Googling on the mechanical generation of oscillating motion (moving something back and forth in the manner of a windshield wiper or a flapping wing) from a source of circular motion comes up ...
180 views

### Are typical worms and worm gears self-locking?

Does anyone know if typical/common worms and worm gears self-locking (plastic or metal)? Are the self-locking ones specially designed (with specific angles) in order to be self-locking? By self-...
212 views

### What is this contraption?

If this is the wrong place for this question, please migrate it to someplace where it's more suitable. So one of my old teachers from my previous school sent me a contraption to try and figure out ...
235 views

### Why don't escalators slow down when people get on?

My friend and I were discussing this earlier: why don't escalators slow down when people get on? We are not interested in any fancy schmancy computers that might adjust their speed for capacity/...
100 views

### High RPM - Stepper vs Brushless Motor

I need to spin a threaded rod to raise a picture on a frame. The weight of the picture + the parts that it hangs on will be around 6 pounds. Two motors are going to be used to lift it via threaded ...
896 views

### How to couple a motor to a screw drive?

I have a simple linear translation stage that is driven by a screw, and I would like to attach a stepper motor to the screw drive. The axis of the screw and the axis of the motor are approximately ...
259 views

### What is the required torque to rotate a 50mm aluminimum plate of weight 100g?

I have a aluminium plate of radius 50mm and thickness 4mm. How much torque is needed to rotate it? In case additional information is required : I have a RS 380 motor, but I guess torque required is ...
2k views

### How to calculate if a motor is strong enough

I am building a machine for a project that should slowly tip a screen forward about 95 degrees, hold for a couple of seconds, and then slowly return to vertical. The design I am working on uses two ...
5k views

### Calculating torque needed to climb a graded hill

I've been designing an electric skateboard which is driven by only one of the rear wheels (for the moment). As I was picking out motors for the board, I soon realized I would need to find a balance ...
31 views

### Calculating the required motor for a mobility scooter

I need to calculate the required motor for a mobility scooter with the following user requirements. The mass of the scooter with passenger = 120kg Max Speed of scooter = 9Km/h ...
327 views

### How to couple/connect shaft to disk?

I'm new to part design/mechanical engineering and I have the following question. Blue: steel shaft, 5/8" diameter, connected to a motor Green: aluminum disk, 10" diameter, 1/2" thick, 3" hole Goal: ...
65 views

### Are all motors controlled with G-Code?

So I have laser cutter. And I am thinking about buying a control unit (this one, to be exact). But my concern here is the following: If the input DXF file contains splines, they will be converted to ...
101 views

### Why servomotor has such low torque compared with stepper motors?

It is easy to found stepper motors with torque over 2NM for a few coins, however, only expensive industrial servomotors achieve this torque. Examples: Stepper motor: 10usd for 1.3nm with 2.8V at 3....
37 views

### Design decisions for variable speed motor switch settings (vs., say, rheostats)

Why do some variable speed motor switches have the highest speed setting next to the off setting instead of the lowest speed setting next to the off setting? For example, most 3-speed household air-...
658 views

### Can Fast Fourier Transform be used to monitor for fault vibrations in a hard disk?

We want to monitor hard disks for present problems or pending failure. Can the Fast Fourier Transform (FFT) of a given hard disk in question, then, be compared with a reference FFT for a perfectly ...
152 views

### What sensors should be used to analyze vibration of a hard disk?

What kinds of sensors can be used to monitor the condition of a hard disk? We want to be able to detect when a hard disk is not operating correctly. Unexpected vibrations may be caused by spindle ...
226 views

### A couple of questions about making an electric hobby car from scratch [closed]

So I'm a high school student doing some competition (a wallet-sized one, unfortunately) and I'm supposed to make an electric car. Think an RC-car, (about that size) without the remote control. I want ...
2k views

### What determines the maximum torque of a DC motor?

What determines the maximum torque of a DC motor? How is this related to the equations $$E=k\omega$$ $$T=kI$$ where $E$ is electromagnetic force / voltage (V) $\omega$ is rotational speed (rad/s) \$...
322 views

### Pneumatic Actuators - System Reversibility. Is it possible to use an actuator to store energy?

I'm very much new to pneumatics and I was wondering if there was such a thing as a reversible pneumatic actuator? I'm designing a system that has to be lightweight, pneumatic and use a mechanical ...
2k views

### How can I apply a load to an electric motor to simulate realistic conditions for an experiment?

I am trying to perform some experiments with a motor and I want to run it under realistic conditions (or at least not unloaded). Is there an easy way to load a motor? A couple ideas I had include: ...
110 views

### Regenerative Braking of DC motor

I'm looking to implement a simple regenerative braking circuit in order to measure how much energy could be regenerated using a DC motor. My knowledge of electronics is very basic to say the least so ...
81 views

### smallest highspeed stepper motors?

In my project I've been using galvo scanners for rotating small mirrors but they seem like an overkill at this point for several reasons: 1) Even though I use the slowest and smallest scanners out ...
51 views

### What thread could this camera motor be?

Firstly, I am sorry that the title of this question isn't helpful. I have bought these motors for a project: 5V 7mm 2 Phase 4 Wire Stepper Motor I assumed that the 1.7mm diameter threaded shaft ...
143 views

### Which type of electric motor I need?

For an experiment I need to use an electric motor, unfortunately I'm not an expert of electric machines. The electric motor I need has to comply with some requests: It must be brushless. It has ...
212 views

### Modelling a DC motor

I am modellign some examples using the modelling language Modelica. Unfortunately, I am not an electrical engineer, so it is hard to understand the physical behavior of the following example (DC motor)...
540 views

### DC Motors synchronization

I would like to know how to synchronize two (nearly)-identical DC motors (approx. 1 Amp/12 VDC each) with permanent magnet, while they are driving on the same surface (railroad Track). The problem is ...
20 views

### clockwork motor output in joules formula

I'm trying to understand the output of clockwork coils in joules or watts for different coils. You know the pullback car or windup pocket watch mechanism. I have heard it also called power in the ...
136 views

### A round, plastic pinion in a lock?

I'm looking at a teardown of a Masterlock. The guts look like this What's strange to me is the black, plastic pinion that appears to be smooth and a strangely shaped cam: Here's the cam magnified: ...
74 views

### How to connect a motor with a 4mm shaft to a propeller that takes 1/2 inch shaft?

I have a motor with a 4mm shaft. I've purchased a propeller that's designed to fit a 1/2 inch shaft. How can I securely couple the two?
2k views

### Rotating two shafts together - coupling rod?

Are there any established (compact and simple) solutions for turning two 5mm rods/shafts side-by-side together by driving a singe motor? The torque is about 5kg-cm. The one I'm thinking of is the ...
130 views

### Why is the Current to Motor less than Motor Rated Current?

I have a motor for a submersible pump with a Rated Current of 8.4A as given in the motor's electrical data. However, when it is running, I record a current of 3.4-3.9A. Is there a fault I am supposed ...
139 views

### Why to avoid over sizing a DC Motor?

Someone told me to avoid over-sizing when using DC Motors. Why? Is this because of sparking and higher wear (brushes) while the motor is running at a lower power rating? Can someone explain?