Questions tagged [motors]

Questions regarding motors. All types of motors, their gearboxes, how to drive an electrical motor etc.

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23
votes
1answer
73k 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 ...
17
votes
3answers
39k 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 ...
15
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2answers
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.
11
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1answer
614 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 ...
11
votes
1answer
2k 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 ...
9
votes
4answers
1k views

How does load force impact load inertia?

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 ...
9
votes
2answers
2k 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 ...
7
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2answers
2k 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.
7
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1answer
132 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 ...
7
votes
2answers
187 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, ...
6
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5answers
24k views

What is Starting Torque?

I'm having a hard time finding an answer from the internet. What does starting torque mean?
6
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4answers
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 ...
6
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5answers
990 views

Ways to brake an axle

I am currently studying Mechanical Engineering and am doing an assignment where I have to design a wire rope tensioner where a wire rope is unspooled from a drum, but the wire has to be at a specific ...
5
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6answers
3k views

Does a motor suffer damage when resistance to the intended motion is met?

I'd like to create something similar to a hydraulic press. I know I need some sort of motor, but I was curious about a fundamental question about motors when used in a system where the force required ...
5
votes
2answers
10k 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 ...
5
votes
3answers
1k 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 ...
5
votes
2answers
408 views

Lifting a cabinet using actuators or scissor lift

Disclaimer: I am not an engineer - just a DIY guy looking for some advice or help please, so please forgive me if I use incorrect terminology :) I am building a cabinet that has a hidden inner cabinet ...
5
votes
1answer
382 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. ...
5
votes
1answer
56 views

Why would a specfication for a motor require that overtemperature protection be realized by modeling heat generation and not with an embedded sensor?

I'm reading the procurement documents for the R211 railcar contract, which is for electric multiple unit subway cars designed for rapid transit applications in New York City. The railcar's propulsion ...
5
votes
2answers
133 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 ...
5
votes
1answer
132 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 ...
4
votes
3answers
1k 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 ...
4
votes
5answers
162 views

Preventing a DC motor from stalling

My team is trying to build a mechanical cannon for a final project for a course and we are running into some problems with our motor stalling. Our motor stalls when the plate hits either side of this ...
4
votes
2answers
91 views

What do I need to operate this motor?

I am currently designing a tennis ball launcher. I am looking to use the friction wheel approach, where you have the ball passing through 2 spinning wheels and being launched by the frictional force. ...
4
votes
1answer
273 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 ...
4
votes
1answer
226 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-...
4
votes
2answers
596 views

How to connect a motor shaft to a plate

I'm trying to drive an aluminium plate using a motor via a 20mm-wide 2mm-thick stainless steel tube. The tube is driven by a 6mm motor shaft via a pulley and the torque will be around 5Nm at most. Is ...
4
votes
3answers
515 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/...
4
votes
1answer
653 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: ...
4
votes
3answers
703 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 ...
4
votes
1answer
122 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 ...
4
votes
2answers
1k 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 ...
4
votes
1answer
1k 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 ...
4
votes
1answer
51 views

Starter direction for methanol engine

I am having a small 2.5cc methanol 2-stroke engine that I am building an electric starter mechanism for. From my research I was under the impression that for a 2-stroke engine like the one that I have ...
4
votes
1answer
347 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 ...
4
votes
1answer
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 ...
4
votes
4answers
84 views

How can I map a global spherical position of a central normal vector to the rotation of 2 perpendicular motors?

I have a machine that rotates two concentric frames. The outer frame has a motor that rotates it relative to the global y-axis, and the inner frame has a motor that rotates it about the outer frame's ...
4
votes
0answers
61 views

Is there any side effect to soft start an AC motor?

I have a ground to water heat pump for my home heating/cooling (scroll compressor). The 3-phase 15kW-peak motor can be soft started but this option is off by default. I'm aware of all the positive ...
4
votes
0answers
70 views

Etymology of the term "journal bearing"

Typically the word "journal" refers to a collection of written records, experiences, or transactions. However, there is a common type of bearing known as a sleeve bearing, radial bearing, or journal ...
4
votes
1answer
359 views

Quick return mechanism for spring-loaded screw

Looking for a way to convert rotary motion to linear, but it should take less energy to get back to initial position than when going from initial position to the end position. Specifically, a screw ...
3
votes
1answer
534 views

How can I calculate the power and torque required for the motor on a wheeled robot/vehicle?

How can I calculate the power and torque required for the motor on a wheeled robot or vehicle if a particular acceleration or movement up an incline is required?
3
votes
2answers
8k views

Type of motor for a small lathe

I am working on a design for a small lathe that could double as a horizontal drilling machine like a Westhoff. My plan is to have specific geared speeds, rather than continuously variable speed. I am ...
3
votes
1answer
412 views

Working out Motor torque

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 ...
3
votes
2answers
665 views

AC Motor On/OFF Control using SSR instead of contactor

I would like to control a 1-phase 3HP motor using a SSR ( the reason being, I need to switch it on/off using a signal (0-5VDC). Are normal SSRs (ex:Fotek 40A model) capable of handling the starting ...
3
votes
1answer
73 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 ...
3
votes
1answer
165 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....
3
votes
1answer
38 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-...
3
votes
1answer
180 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 ...
3
votes
1answer
242 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 ...
3
votes
1answer
4k 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) $...

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