26
You have the right concept, but slipped a decimal point. 5 cm = 0.05 m. The gravitational force on your 450 g mass is 4.4 N as you say, so the torque just to keep up with gravity is (4.4 N)(0.05 m) = 0.22 Nm.
However, that is the absolute minimum torque just to keep the system in steady state. It leaves nothing for actually accellerating the mass and for ...
21
These types of motor configurations are used in the cellphone's vibrate/buzzer function. Here is a Youtube video demonstrating the vibrate function and two other references:
How it works:Cell phone vibration motor?
iPhone 5 / 5S Vibrator Motor Replacement
Vibration Motors by Precision Microdrives
Click on image for a larger version of the image.
These are ...
answered Jul 21 '15 at 10:08
Mahendra Gunawardena
7,0955 gold badges24 silver badges63 bronze badges
20
A differential is a mechanical device designed to do exactly what you propose. It will allow the two motors to spin at slightly different rates while still combining the power. The most common use of a differential is in the drivetrain of an automobile in which it is used to power both wheels from one engine while still allowing the wheels to spin at ...
19
While a mechanical differential does what you ask, you don't really need it.
You can connect two identical electric motors together on the same shaft. There is no "slipping out of sync" because there isn't a issue of sync in the first place. Drive the two motors the same and both will develop close to the same torque. One will have slightly more torque ...
13
Do you mean, for example, a bus entry door? It may be as simple as the "service factor" for motors ("electromagnetic devices") as compared to pneumatics. Inexpensive motors with sintered bronze bushings wear out, and better ones with actual bearings must be routinely lubricated. Air-operated cylinders are cheap and last a very long time, with the air ...
13
The device you are looking for is called a slip ring such as the one shown below. These devices use internal components which maintain contact as they spin (old ones used brushes) allowing them to turn by an unlimited amount in either direction.
12
I think you're overcomplicating things. To push 85 kg up a 15% slope against gravity of 9.8 m/s2 requires a force of
$$ \sin (\arctan (0.15) ) = 0.1483 \approx 0.15 $$
$$F = 85 kg \cdot 9.8 \frac{m}{s^2} \cdot 0.15 = 125 N$$
With an 80 mm wheel, this requires a torque of
$$T = 125 N \cdot 0.04 m = 5 Nm$$
To do this at a forward speed of 11.11 m/s ...
12
I laid everything out so you should only need to read it from top to bottom and look backwards for variables, never forward. I also tried to lay it out so hopefully you know where everything is coming from (as long as you have a basic understanding of power, torque, force, and friction...maybe even if you don't).
$ \mu_{roll}$ = coefficient of rolling ...
10
Oddly enough, this problem can be fixed using a set of car keys and your wallet. Here are the steps to follow:
1) put the keys in the ignition of your car, start it, and drive to the motorcycle scrapyard.
2) once there, exchange several pieces of local currency for a gear pulled out of another identical motorcycle.
3) place the gear in your pocket and ...
10
The answer depends on the specific type of motor you intend to use, but in general: when a motor is loaded down, it draws more current, which means its windings get hotter at the same time that the cooling fan attached to the motor shaft is being slowed down. if this heat is allowed to build up, it will eventually cause the insulation on the windings to fail ...
8
There are two different aspects to start-up torque. One is associated with the motor and the other with the system which you are trying to drive.
The start-up torque of a mechanical system is the minimum torque required to get it moving from a standstill. the start-up torque of a motor is the maximum torque which it is capable of producing from a ...
7
They are smoother and if something gets caught in between them then the maximum force it can exert is capped depending on the pressure and the piston area. This means that a trapped limb is less likely to get crushed.
In an emergency (a typical concern for public transport) you only need to open a valve (pulling the emergency open will do that) and push to ...
7
The usual solution is to use gears, possibly with a toothed belt or chain to connect them.
A single connecting rod like you show is not sufficient — there's an ambiguity when the rod is at the extreme left or right position, allowing the driven shaft to turn in either direction. A train locomotive uses two connecting rods, 90° out of phase on ...
7
In the lower right corner of the document/drawing, you can see four (or five) lines of text upward: UNIT: mm
Another piece of useful information in the data panel is the scale, shown there as 3:1. You would be able to measure the components of the drawing and divide by 3 to determine real dimensions, but only if the drawing is printed to 1:1 and not "fit to ...
7
It depends on the specific type of motor, as @nielsnelson mentions, but it also depends on what you use to drive the motor.
In general, a motor that's designed to run continuously isn't going to take well to being stalled for any length of time, unless its drive voltage (and frequency, if it's an induction or synchronous machine) is reduced.
There are ...
7
Relatively low lifting requirements (100 kg)
Relatively fast lifting speed (80 fpm -> .4 m/s)
The first part of your power calculation was wrong. There's no need to go into pulley diameters at this early stage of the calculation. Let's start at the load hook.
100 kg ~ 1 kN. Speed > 0.4 m/s. So power > 400 Watts.
That's mechanical power, after a ...
7
In the past whenever I needed a rotary encoder, I took apart a computer mouse. I do not know if they will meet your requirements, but there's nothing cheaper.
6
Is the torque required to make something that is not turning start turning.
You can think of starting torque as an instantaneous value (the torque just before the motor starts moving). You can also thing as the torque function from that moment until the motor reaches the desired speed.
The torque provided by a motor is
$T_{motor}(0) = T_{static friction}\\...
6
That is a micro vibrating motor to produce the "buzz" effect from your phone.
I used much much larger vibrating motors, air driven, on the bottom of my Class 7 dump truck. Mounted under the bed, they would vibrate the bed, loosening the material so it would flow out cleanly.
6
"Starting torque" and "locked-rotor torque" are the same thing. So if you run across the later term, you can treat it as a synonym for "starting torque." The NEMA MG-1 definition of locked-rotor torque is:
"the minimum torque which [a motor] will develop at rest for all
angular positions of the rotor, with rated voltage applied at rated
frequency."
6
Electric motors typically only operate well at high speeds, and compared to something like an internal combustion engine, relatively low torque. Fixed gear ratios are used to cope with this inherent limitation.
Additionally, some designs will use a gear train so that they can design a point of failure in their system that is not the motor. If the system, ...
6
A given mass of copper and iron can only produce so much torque : increasing torque further would require more current which means (a) the increased magnetic flux saturates the iron and (b) the I^2R losses in the copper overheat the motor. So more torque requires more iron and copper; i.e. a bigger, heavier, more expensive motor.
Furthermore, because ...
6
Let's first compute the model. The control design is a separate effort.
The torque applied to the drum is $n T_M $, where n is the gear ratio and $T_M$ is the output produced by the motor. $T_M= K_T i(t)$, where $K_T$ is a proportionality constant and $i(t)$ is the motor current.
Now we can write the equations for the mechanical system:
$$ m y''(t)+m g-k (...
6
The fundamental problem in this case is that the turbine in not powered by 'wind' as such but by the relative motion of the car through the air.
This is not 'free' energy, because the turbine must do work to generate energy it must also exert a net force opposing the motion of the car ie drag. So any energy you generate with the turbine must ultimately be ...
6
For having dismantled a wiper motor once,
The basic principle is exactly as shown on the video, but the wiper is then linked to the to the rotation point of the rocking bar and not to the bar itself.
Here is a schematic on how it works:
I think this system is quite standard, but there are many type of wipers and I am quite sure that a few constructors ...
6
The wires in your home have resistance. Current going through those wires causes a voltage drop. The startup (inrush) current of electric motors can be several times their normal operating current. It's impossible to know exactly what the startup current is for your motor without knowing specifics supplied by its manufacturer. The high startup current occurs ...
6
In the wire & cable business, the device you describe is called a dancer, for the way its components move about while regulating the tension in a rope or wire being unspooled from a large coil.
The simplest examples use a rim brake which drags against the flange on the big spool. The rim brake is on a lever arm and the end of the arm is attached to a ...
5
Initially
Assume an ideal motor with no mechanical losses and
Operation in a perfect vacuum.
Call the two portions rotor and stator - with all attached parts such as controller and power pack forming part of one or the other.
Start at rest relative to a "fixed" frame of reference.
Rotor and stator will rotate in opposite directions with the '...
5
The vast majority of worm gears are self locking naturally, it wouldn't be considered a special feature, just something you should confirm in your final design. Generally any single start worm screw will be self locking, there are multi-start worm screws that may not be.
If you are doing something where backdriving would be hazardous (not just risk minor ...
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