Transmission Definition and 753 Threads

A transmission is a machine in a power transmission system, which provides controlled application of power. Often the term 5-speed transmission refers simply to the gearbox, that uses gears and gear trains to provide speed and torque conversions from a rotating power source to another device.The term transmission properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), differential, and final drive shafts. In America the term is sometimes used in casual speech to refer more specifically to the gearbox alone, and detailed usage differs.
The most common use is in motor vehicles, where the transmission adapts the output of the internal combustion engine to the drive wheels. Such engines need to operate at a relatively high rotational speed, which is inappropriate for starting, stopping, and slower travel. The transmission reduces the higher engine speed to the slower wheel speed, increasing torque in the process. Transmissions are also used on pedal bicycles, fixed machines, and where different rotational speeds and torques are adapted.
Often, a transmission has multiple gear ratios (or simply "gears") with the ability to switch between them as the speed varies. This switching may be done manually (by the operator) or automatically (by a control unit). Directional (forward and reverse) control may also be provided. Single-ratio transmissions also exist, which simply change the speed and torque (and sometimes direction) of motor output.
In motor vehicles, the transmission generally is connected to the engine crankshaft via a flywheel or clutch or fluid coupling, partly because internal combustion engines cannot run below a particular speed. The output of the transmission is transmitted via the driveshaft to one or more differentials, which drive the wheels. While a differential may also provide gear reduction, its primary purpose is to permit the wheels at either end of an axle to rotate at different speeds (essential to avoid wheel slippage on turns) as it changes the direction of rotation.
Conventional gear/belt transmissions are not the only mechanism for speed/torque adaptation. Alternative mechanisms include torque converters and power transformation (e.g. diesel-electric transmission and hydraulic drive system). Hybrid configurations also exist. Automatic transmissions use a valve body to shift gears using fluid pressures in response to engine RPM, speed, and throttle input.

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  1. jegues

    Transmission Line, Max Real Power Transfer

    Homework Statement A 230kV, 160km long transmission line has the following parameters expressed on a 230kV, 100MVA base. R = 0.0151 X = 0.1476 Y = 0.288 The sending end voltage of the line is held constant at 1.0 pu. The load at the receiving end has a lagging power factor of 0.8...
  2. B

    Approximate transmission coefficient of a square barrier

    Homework Statement Two conductors are separated by an insulator. Model the insulator as a square barrier of height 0.01 keV and a width of 5nm. Determine the transmission coefficients for electrons of 7,000 meV. The only thing is I have to use the approximation formula for finding the...
  3. B

    Determine the transmission coefficient for an electron

    I have an example problem in my book. I have uploaded an image. The part I can't figure out is how to do the last part of the problem to come up with the transmission coefficient. The book gives me a formula but when I plug in all the numbers from the formula into my calculator I get a...
  4. M

    Antenna/Balun transmission line query

    Hi, I'm building a Yagi antenna for the 440Mhz ham band. The outline I'm following uses a driven element of a folded dipole; Z = around 288 ohms. I am feeding this with 50 ohm source. Many internet sources describe a balun made from a 1/2 wave length coax (velocity factor adjusted). I will...
  5. C

    Relativistic Wavelength of Electron in Transmission Electron Microscop

    [I could not fit the last "e" into the title] Hi! I am writing a report on TEM, and was asked to consider the effect of accelerating voltage on the resolution. Since resolution in the light microscope is limited by the wavelength of visible light, we obtain much higher resolutions in a TEM...
  6. ~christina~

    Advantage/Purpose of Transmission vs Absorbance in calibration curve

    Homework Statement The problem involves a calibration curve which was created and where % T vs concentration was favored for use over the usual Absorbance vs concentration and a question of why would this be used in favor over the latter relationship curve was presented. other details...
  7. M

    Two-conductor transmission line, find the potential difference V of th

    https://www.physicsforums.com/attachments/66302Two-conductor transmission line, find the potential difference V of the two conductors.? Two-conductor transmission line. At point P (x=43 cm, y=32 cm) in Fig. 2-10, |E|=450 V/m. If s=25 cm, h=29 cm, and r=12.5 cm, find the potential difference if...
  8. tipu_sultan

    What is the meaning of the CESMM3 Ref in BOQ of Transmission & Distrib

    What is the meaning of the CESMM3 Ref in BOQ of Transmission & Distribution? In the Bill of Quantities of Some project of Electrical Transmission and Distribution I came across the CESMM3 Ref when I searched in the net I know that it is the " Civil Engineering Standard Method of...
  9. H

    How Does Wireless Power Transmission Work?

    Wireless electricity transmission works by passing alternating current through one coil to which another coil corresponds and thus is coupled. At least this is the way WiTricity explains it. They also say that it's very much like mechanical resonance and that's why it's more efficient over...
  10. K

    Increase RPM & Calculate Torque with Gearbox

    Hi guys, i would like to ask how do i increase my rpm using a gearbox (2,3,4 stages i don't mind) Input rpm 10 target output rpm 1500 and after that how can i calculate my torque?
  11. A

    Satellite relay system and transmission losses

    Hello. Below I have a problem I can't quite understand to the full: http://www.israup.net/images/027d25c3acde86a09bcb9e1ed869560a.png http://www.israup.net/images/6757f5c30cbcfe051295b1b1e4614489.png And that is the suggested solution...
  12. D

    Transmission coefficient in reaction rate theory

    This question relates to rate constants of transition events. The transmission coefficient κ reduces the value of the rate constant compared to the transition state theory (TST) value. I understand κ to be defined as the probability that a reaction coordinate q will proceed to product given that...
  13. L

    Finding the Power Loss Through a Transmission Line

    Homework Statement A factory receives 120kW of power from a power station 20km away via transmission lines. If the resistance in the power lines is 0.5Ω/km, what is the power loss in the lines if the electricity is transmitted at 100kV (Approximate to a simple DC circuit). Homework Equations V...
  14. PsychonautQQ

    Can Resonant Transmission happen when U > E?

    My textbook had a section where a particle beam was going over a barrier where E > U and then right after that had a part about resonant transmission. It then went on to talk about Tunneling through a barrier when U > E. It didn't give a new resonant transmission equation and i assume the...
  15. U

    How Do EM Waves Behave in Transmission Lines with Varying Frequencies?

    Homework Statement (a) Find the capacitance per unit length and find the inductance per unit length of a transmission wire above a infinite conducting plane. I used the image method (b) Show that EM waves can propagate, and find their speed and the characteristic impedance of the line...
  16. I

    Hollow shaft power transmission

    Hello all this is my first post so i hope i can give you the relevant data in the correct format, also thank you for any assistance :) I am to find the OD of a hollow shaft when the shafts ID is 0.75 of the OD dimension, the shaft transmits 3MW at 200Rpm. The Shear stress max is 55 MN/m2 and...
  17. B

    Archived Derive the general solution for current in a lossless transmission line

    Homework Statement Find the general solution for the current I(z,t) associated with the voltage V(z,t).Do this by substituting [1] into [2] and [3], integrate with respect to time, and then take the derivative with respect to z. Homework Equations V(z,t)= f+(t-z/vp) + f-(t+z/vp) [1]...
  18. S

    Transmission Line Homework - Determine Input Impedance

    Homework Statement Attached is the problem. I am a little confused as to how I should be approaching this type of problem. If I Determine the input impedance for the first segment of transmission line and load impedance on the right, is that going to be in parallel with Z_L on the left? I am...
  19. F

    How can I find resources for creating a wireless power transmission project?

    anyone can help me l want to make an electrical project wireless power transmission .can you please provide me some useful link where l can found circuit diagram and list of necessary equipment.
  20. O

    Transmission Line: 300km vs 150km

    Hello i would like to know what is the different between 300km and 150km in transmission line.. thanks
  21. S

    Transmission Line Length for Real Input Impedance?

    Homework Statement Hey guys. I have a transmission line with a known characteristic impedance (50 Ω) of length L that is connected to an antenna that has a complex impedance of (50-j25)Ω. I am having extreme difficulty determining the minimum length (expressed in wavelengths) of line such...
  22. J

    Radiowave Transmission: Where Does Electric Field Come From?

    Hi, I am having difficulty determining where the electric field comes from when an electromagnetic wave is emitted by an antenna. I know that the charges accelerate between an AC voltage but where does the electric part of the EM wave come from? In a normal wire there is no electric field from...
  23. T

    Wavelength on power transmission lines

    At the power-line frequency (50Hz), the wavelength of electromagnetic waves in free space is 6,000 km. Similarly, the phase velocity of voltage/current waves is about 4,000 km at this frequency. The question is, why do we bother about the wavelength at all at the power-line frequency, when the...
  24. M

    What is the impedance of a matched transmission line

    Hi, I've been coming to physicsoforums for years, I love the community! This might be my first post though. I am wondering what the impedance is of a transmission line with a matched stub on the end. The impedance of the line is 50 Ohms, and the impedance of the stub is 50 Ohms. Is the...
  25. F

    Transmission of PWM signal not working.

    Hey guys, So I'm working on a project currently being built off of a cheap commercial Quad-copter (Syma X1) as it's base platform. Just as a little background I am trying to make it so that it is not controlled by a remote (that is pushing knobs and levers up and down to control it) but by EMG...
  26. R

    Transmission Line Simulation Questions

    I am simulating an unshielded twisted wire pair of a communication network, Controller Area Network. Bus Speeds taken into consideration are 250/500/1000/2000 kbps. Depending on the physical dimensions of the wire and insulation dielectric constant, I have computed the R,L,C,G parameters...
  27. V

    Transmission line energy loss/length.

    Here are some figures from this article. Wiki: Electric Power Transmission Unless I made a mistake, that would be approximately 100W to 200W loss per foot. That's some 6 to 13 times as much as the percentage loss in the example above, but it doesn't tell me what is the line length or energy...
  28. H

    Possible Rectangular Potential Barrier Transmission Problem

    1. The Problem Statement An electron of effective mass m* = 0.2me and energy E = 0.1 eV hits a barrier of height 0.4 eV and width t = 5 nm. What is the probability of transmission through the barrier? Use the simplest estimate which is an exponential function. Homework Equations I think...
  29. A

    Transmission & Distribution Department or Power Generation Department

    If you are a fresh graduate of BSc Electrical Engineering and you are asked to choose either Transmission & Distribution Department or Power Generation Department, which one will you choose? And why? Please your inputs will help me decide, so help me out. Airer
  30. M

    Suggest a transmission electronic kit

    Hello, I want to build transmitters and receivers and I wonder if there is a tool kit which contains components building these circuits such as VCO, crystal oscillators, low value capacitors and inductors etc etc with various transistors. Also is there a transmitter that I can buy which allows...
  31. D

    QM - Transmission coefficient for square well

    Homework Statement A steady stream of 5 eV electrons impinges on a square well of depth 10 eV. The width of the well is 7.65 * 10^-11 m. What fraction of electrons are transmitted?Homework Equations The following equation for the transmission coefficient, T, is given: T = [1 + \frac{V_0 ^2...
  32. siddharth23

    Maximum transmission ratio of a spur gear pair

    WHat is the permissible maximum transmission ratio of a Spur gear pair? I read somewhere that it is 1:5. What wil happen if this is exceeded?
  33. K

    Representation of a 1 phase transmission line as line charges

    Hi, According to what I understood, when a terminal is connected to a line, it causes electrons to flow in one direction. And so for a single phase transmission line in parallel if connected to supply, then in one side electrons will be flowing in one direction and the same electrons will be...
  34. J

    Unified or Fractured? Universe Info Transmission Speed

    For some reason I find it hard to comprehend that at the natural base level of existence (whatever that means), that the information-scape (all the stuff that is happening throughout space) is totally fragmented from each other, except of course for the "slow" transmission of information to...
  35. A

    Two-port network transmission parameters?

    two-port network transmission parameters?? Homework Statement Homework Equations t[A B]=[t11 t12] [C D]=[t21 t22] The Attempt at a Solution so, first thing i did was find the equivalent capacitance/inductance. C(eq)=-j0.5 and L(eq)=j0.5. using these values as I was confused by parametric...
  36. Y

    Help with vector calculus in reflection and transmission of plane wave

    This is not a homework, this is concerning reflection and transmission of electromagnetic wave ( plane wave) at a flat planar boundary between two media. But the work in question is pure vector calculus. I ultimately want to proof if ##\vec E_I=\hat y E_I## then ## \vec E_R## and ##\vec E_T##...
  37. S

    Compass deflection by overhead transmission lines

    Problem Description: A hiker is reading a compass under an overhead transmission line that is 5.1m above the ground and carries a current of 807A in a horizontal direction from North to South. Assume the Earth's field is of the order 0.5*10^-4T. A) Determine the magnitude of the field produced...
  38. C

    Overhead electrical transmission cable sag questions

    These are questions for electrical engineers involved in electrical power transmission by overhead line and knowledgeable about current practices. - What catenary sag is normal, under normal conditions of weather and transmitted current? [obviously the answer will depend on the distance...
  39. G

    Using piezoelectricity for data transmission.

    I am starting my 3rd year in September and I've decided to start thinking about research topics early. I'm quite interested in piezoelectricity along with it's discovered and perhaps undiscovered applications. This is my first idea; I have watched a lot of nature programs and I have seen that...
  40. Y

    Question in reflection and transmission at oblique incidence.

    I am reading Griffiths p387. It is my understanding that \tilde E(\vec r,t)=\hat r E_0 e^{j(\omega t-kr)} Where ##\vec r =\hat x x+\hat y y+ \hat z z## is the positional vector from the origin to the observation point ( x,y,z). \Rightarrow\;\tilde E(\vec r,t)=\hat r E_0...
  41. Y

    Question of reflection and transmission of TEM wave in normal incidenc

    Suppose TEM wave in +z normal to a boundary on xy plane at z=0. We know E & H are tangential to the boundary. Let ##\vec E_i=\hat x E##, be the incident wave towards the boundary therefore incident H is ##\vec H_i =\hat z\times \hat x \frac {E_i}{η}=\hat y H##. I have a few questions: 1) How...
  42. F

    Transmission lines parallel fault

    I am trying to draw the bounce diagram for the trans line in the picture attached to my thread. Sorry won't let me upload... https://www.dropbox.com/home#!/lightbox/home/Year%202/Semester%202/mbgm9mw6 I am not sure what to do here because I have never seen anything like it before. It...
  43. P

    Does a magnet affect antenna transmission?

    I am working with an application where we have a magnet in close proximity to an antenna in the 20 - 25 GHz range. If there IS and affect of the magnet to the antenna's transmission, does the "near field" calculation apply (λ/2xpi)? If the antenna is out of the near field, is there no affect...
  44. U

    Electric Grid Question - Elevated Transmission Lines

    Electric Grid Question -- Elevated Transmission Lines Hi, Our teacher gave to us an homework which is if we carry transmission lines at 20000 m (20km) high from Earth face, what is this application's benefits and harms? Can anyone help me? Already thanks for your replies...
  45. C

    High power transmission lines: underground?

    In the Midwest (Iowa, etc.), we get plenty of storms, mostly Winter, and power lines go down frequently. Someone is about to build a new high-power transmission line across my County (and too near my property!), and I can't figure out why it is not mandatory in the 21st Century that all...
  46. 7

    How Does Quantum Tunneling Affect Particle Transmission?

    Lets say we have a tunelling problem in the picture, where ##W_p## is a finite potential step: If particle is comming from the left a general solutions to the Schrödinger equations for sepparate intervals I, II and II are: \begin{align} \text{I:}& & \psi_1 &= \overbrace{A e^{i\mathcal L...
  47. P

    Bluetooth transmission and FHSS

    Hi, In very simple terms am I correct in thinking that bluetooth uses FHSS during signal transmission which involves changing of the carrier frequency at set intervals, essentially allowing the signal to change channels within the 2.4GHz band? Thanks
  48. D

    Can electrons enable instant data transmission across the universe?

    As I understand, electrons cannot be on the exact same level as another one in the universe. If we could move one electron in one placed and somehow monitor another ones reaction - would it be possible to instantly transmit data anywhere in the universe?
  49. W

    Calculating FM transmission distance

    Hi -- I am trying to calculate the signal distance for a 2kw FM radio station broadcasting with a 157' antenna over average terrain. The FCC calculator requires field strength, and I don't have a clue what that would be. Can I roughly calculate broadcast distance using the known variables...
  50. 7

    Transmission and Reflection on a potential step

    Lets say we have a potential step with regions 1 with zero potential ##W_p\!=\!0## (this is a free particle) and region 2 with potential ##W_p##. Wave functions in this case are: \begin{align} \psi_1&=Ae^{i\mathcal L x} + B e^{-i\mathcal L x} & \mathcal L &\equiv \sqrt{\frac{2mW}{\hbar^2}}\\...
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