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. K

    Three Phase pi-section model of power system transmission lines

    I am using the "Three-Phase PI Section Line" Matlab-Simulink block from Simpowersystems blockset for modelling an electric power system transmission line. I had obtained the data from a research paper regarding the transmission line specifications (provided as sequence values). Since I am...
  2. M

    Power transmission through space

    If we had a source of power in space at some distance is there any feasible way it could be transmitted to the Earth and converted to usable power here? Assume an almost unlimited source that can be converted to anywhere in the EM spectrum so efficiency is desirable but not required. The only...
  3. D

    Why are Transmission Voltages in India Multiples of 11kV?

    why transmission voltages in India are multiples of 11kv?
  4. A

    Analysis of Transmission Line Load at 900MHz

    Figure below shows a load made up of a 50 W resistance, a 15 nH inductance and a 22 pF capacitance connected in series. The load is terminated to a two-wire transmission line with characteristics impedance of 50 W. (i) Determine the load reflection coefficient at an operating frequency...
  5. A

    What Is the Load Reflection Coefficient and SWR at 900 MHz?

    Figure below shows a load made up of a 50 W resistance, a 15 nH inductance and a 22 pF capacitance connected in series. The load is terminated to a two-wire transmission line with characteristics impedance of 50 W. (i) Determine the load reflection coefficient at an operating frequency...
  6. T

    Understanding Transmission Design: Connecting RPM from Gearbox to Sprocket

    im confused. how do you relate the RPM from gearbox to a sprocket?
  7. A

    Reflection and transmission of signal

    How do I determine what percentage of a signal is reflected and what percentage goes through a wall. I know that I am over simplifying things, but for the purpose of my project I need a simple answer to this problem. What parameters are needed for the solution and how do we calculate this...
  8. S

    Yet another wireless power transmission thread.

    Hi everyone, this is my first post on the forums :redface: OK so I want to design a microwave power transmitter and I need a few opinions before I make any commitments. I haven't made many complex circuits before, but I am going to do my homework if this is viable and break it into chunks...
  9. R

    Emissivity & Thermal Transmission

    Stainless steel has emissivity of 0.12. It means it only absorbs 12% of radiation and reflect the rest of the 88% as well as tranmitting the 12%. Now if you heat the stainless steel to say 300 Celsius. It won't transmit the 300 Celsius but only a little of it. This is why thermal imagers can see...
  10. J

    33kV 3phase fault causing transmission line entanglement

    Good morning Gentlemen (and Ladies), I'm looking for some help from you HV experts out there. I have had an event where it is believed that a flooded transformer connection box induced a fault on to a 33kV 3phase transmission line, and the fault current was enough for the repulsive forces...
  11. SredniVashtar

    Four wires transmission line for data

    I read on Kraus' "Electromagnetics", 4th edition (p 583), that four-wire transmission lines (in a quadrupole configuration - the conductor with the same polarity are in diagonal) improve shielding. + - - + I tried to find some more information about this sort of transmission lines but...
  12. M

    Transmission probability (tunneling) question

    A beam of 11 eV electrons is directed towards a barrier of potential Vo = 3.8 eV. Compute the width of the barrier for which the reflection is maximized (Note: this is NOT asking for when reflection is 100%). Transmission probability for E > Vo: T = [ 1 + (Vo²*sin²(βa))/(4E*(E - Vo)) ]^(-1)...
  13. R

    Wireless music transmission using lasers

    Hey all. I'm currently working on a project where I use a laser to transmit music playing from my iPod. The laser is hooked up to the iPod through a circuit, and there is a solar cell that the laser is pointed at. There are two wires coming from the solar cell that are connected to a stereo...
  14. R

    Grabbing the ends of a transmission line

    If you have a two-wire transmission line that is open-ended at the load, and connected to an alternating voltage generator at the source, then the voltage between the open ends can be as high as twice the voltage of the generator. However, if the two ends are shorted, then the voltage would be...
  15. timthereaper

    Power Transmission via AC current

    I'm a mechanical engineer and I'm really interested in electrical systems. I understand a fair amount about the basics of E/M and circuits. But no matter how much I read, I can't wrap my head around how AC systems generate power. I do know they work (obviously, right?), but I'm trying to imagine...
  16. P

    Power Loss in transmission lines: Which method is correct?

    Here is the problem: http://postimage.org/image/1jy6nol5w/ Method 1: Steps 1. Calculate V(T1)=12*10=120V, V(T2)=10*10=100V 2. Since V(3)=10V and I(3)=1A, P(T3)=10W 3. Since not otherwise stated, Assume transformers are perfect. 4. So P(T3)= P(T2) = 10W 5. known...
  17. C

    How does a coaxial transmission line work?

    On a coaxial transmission line is there AC current running through the center wire? And this AC current produces EM radiation that bounces down the wave guide. So is the purpose of this transmission line to send the signal via radio waves. And is this how cable tv works, are radio waves being...
  18. F

    Optics - Transmission of plane wave at oblique incidence

    I have 2 questions that need help with, Considering the following plane wave, E= 30 (0.866 i + 0.5k)exp{i(-0.5x + 0.866z)} firstly how can i deduce the direction of the electric field oscillations? And finally, if the wave is incident on a dielectric interface between medium of Er=2...
  19. C

    Health risks with radio transmission?

    Ok I've done my research and so long as the transmitter isn't outputting at a high level of power, you'll be fine. Why I ask is because I'm looking into getting a job with a small company, where they install network elements such as optical and radio transmissoin (and multiplexers). Now I...
  20. C

    Are there any health risks with radio transmission?

    Ok I've done my research and so long as the transmitter isn't outputting at a high level of power, you'll be fine. Why I ask is because I'm looking into getting a job with a small company, where they install network elements such as optical and radio transmissoin (and multiplexers). Now I...
  21. T

    Transmission line charateristics measurement?

    Transmission line charateristics measurement?? Dear all, I want to do cable analysis of a 3800m long twisted pair wire to set up a communication system. It is not usual twisted pair wire (telephone), has different impedance, R=194, L=4mH, C=180uF. The things to be analyzed are...
  22. O

    How does energy transmission work in waves?

    After looking at my notes and http://cnx.org/content/m16027/latest/" I have become utterly confused about Energy transmission in Waves. What? In a traveling wave KE=PE? If so, when a particle is at its max displacement, KE=PE=0 and so KE+PE=0 and yet then a particle is as its mean...
  23. M

    Transmission and reflection coefficients for potential barrier

    Homework Statement An electron with kinetic energy 5 eV (8.01E-19 J) passes through a 3 eV (4.806E-19 J) potential barrier. There are certain widths for this potential barrier in which the transmission probability will equal one hundred percent and the reflection probability will equal zero...
  24. P

    1 wire power transmission using coils.

    Hello Physicists, I am doing my final year of High School in Australia and our current topic is magnetism and related fields. Physics is my favorite subject after maths and I tend to query a lot of things. Here is my basic Idea: My basic instinct tells me that the orange wire must be...
  25. J

    Loss of signal power in radio and wire transmission

    Homework Statement For radio transmission in free space, signal power is reduced in proportion to the square of the distance from the source, whereas in wire transmission, the attenuation is a fixed number of dB per kilometer. The Attempt at a Solution this is not the whole problem...
  26. F

    Can Single Wire Transmission Use a Goubou Wave?

    hello forum, has anyone heard before about a Goubou wave and single wire transmission? I always thought that for a circuit to properly work two conductors were needed, the signal conductor and the return conductor, both in DC and AC... Is that true? thanks. fisico30
  27. M

    High voltage power transmission and joule's law

    Hi, Power transmission over long distances from power plants to local power grids is often done over DC with relatively high voltages/tensions. The argument for this is that since, by Joule's law, power dissipation due to heat by a resistive element is given by I^2 * R, lowering the current...
  28. L

    Understanding Reflections in High Speed Digital Designs

    In high speed digital designs, there is a series terminating resistor to match the output impedance of the driver IC with the transmission line on the PCB. Some think the purpose of this resistor is to decrease the drive of the IC. How do I convince them its not to decrease the (current) drive...
  29. A

    Why does high voltage transmission reduce Joule losses?

    I'm a bit confused about why power is transmitted at high voltage for transmission over long distances. This is generally explained as reducing Joule losses, P = I^2 R, and we minimize the current by maximizing the voltage. However, a trivial re-arrangement using Ohm's law gives also P = V^2...
  30. Y

    Question on finding inductance of parallel plate transmission line.

    Find the inductance per unit length of parallel plate tx line width = w and space =d between the two plates. w>>d. My question is whether the total inductance is twice the calculate inductance because total inductance is the sum of inductance of the top and the bottom plate. But it seems all...
  31. G

    The Klein Paradox - Exploring Beyond the Negative Coefficient of Transmission

    The Klein Paradox is the name given to the following prediction of Klein Gordon's equations. If you send a current of electrons against a potential barrier of height V such that the energy of the incident electrons is less then V - m, you should observe a current of positrons coming out of the...
  32. H

    Force Analysis of a Power Transmission Shaft

    Homework Statement The 150 mm long shaft AB transmits a power of 58.5 kW @ 1400 rpm A helical gear is located at 100 mm from the left bearing of the shaft Tangential pressure and helix angles are φt=24 and ψ=23 degrees, respectively; and the pitch diameter is 20cm Draw bending moment...
  33. E

    Taylor Approximation (I think) on Transmission Coefficient

    Homework Statement I have this equation: T=(1+\frac{U_{0}^{2}}{4E(U_{0}-E)}sinh^{2}(2 \alpha L))^{-1} Where α is given by: \alpha = \sqrt{ \frac{2m(U_{0}-E)}{\hbar^{2}}} I have to show that in the limit αL>>1 my equation is approximately given by...
  34. H

    How are the speed ratios distributed for a power transmission problem?

    This is the solution to a question. I have followed it through with my own calculations and I'm getting good numbers. However I don't understand how the numbers for 8. are decided. Why is the last one 1/4? I need to work this out because it is putting my lifting speed 0.06m/s below the limit for...
  35. S

    Transmission coefficient in a barrier penetration.

    An electron having total energy E=4.46 eV approaches a rectangular energy barrier with U=5.02 eV and L=949 pm. Calculate this probability, which is the transmission coefficient. I thought this would be an easy one, given that T=e-2GL and G=\sqrt{\frac{2m(U-E)}{H}} where H is the...
  36. N

    Wireless energy transmission via sound waves

    Today in my high school physics class, we were shown that object 1 vibrating at object 2's natural frequency, can cause object 2 to vibrate. So since you are transferring energy, i was wondering if its possible to use ultrasonic or infrasonic sound waves to vibrate a magnet, causing a current to...
  37. G

    Transmission and reflection for olique incidence at a uniform dielectric slab

    1. Homework Statement A di-electric slab of thickness d is between two differing dielectric media (u0,e0/u1,e1/u2,e2). What is the total reflection at the first interface and transmission through the second interface of the slab. The incident wave is in the x-z plane with an angle of...
  38. M

    Transmission probability of a massive particle

    Homework Statement Consider the potential V=V_0 d[\delta(x-a)+\delta(x-a)]. Find the transmission probability of the potential for a particle of mass m and wave number \sqrt{\frac{2mE}{\hbar^2}} incident on the potential. Discuss the behavior when ka~\pi/2. Homework Equations Schrodinger's...
  39. 1

    Transmission zeros of driving point impedance functions

    Hello all, This question might be at the same time both general and very specific. Admittedly, it has been over 10 years since I really thought about circuit analysis, but I hope I might get some help here! So, thanks in advance! I will ask a few questions here to make the presentation...
  40. A

    Question on Finding Transmission Coefficient

    Homework Statement Find the transmission coefficient for the potential V(x)=-\alpha\left[\delta\left(x+a\right)+\delta\left(x-a\right)\right], where alpha and a are positive constants. Homework Equations T \equiv \frac{\left|F\right|^{2}}{\left|A\right|^{2}} The Attempt at a Solution...
  41. S

    Solve Transmission Losses: 50kW @ 230V, PF 0.6 Lagging

    I need help with this tutorial question I cannot solve! a consumer demands 50kW at an effective voltage of 230V. supply system can be represented by a 0.1ohm resistance. Find the transmission losses in the event of the load being supplied with a power factor of 0.6 lagging. I know the...
  42. Y

    Question on Q of a quarter wave transformer using lossy transmission line.

    I don't know whether this is the right place, should actually belong to EE but my experience is you really don't get a lot of help in EM over there because I notice there is only one or two people that attempted answer these. This is regarding to finding the Q factor of a lossy tx line using...
  43. N

    Calculating Efficiency and Power in a Belt Drive: A Homework Guide"

    Homework Statement A belt drive transmits 56kW from the driver pulley to the driven pulley. If 2.5kW is lost in belt friction, calculate: 1. kW's supplied by driver pulley 2. efficiency of the belt drive expressed as a percentage. Homework Equations %Efficiency = (power...
  44. H

    Simple Transmission Line Question

    Say you had a lossless transmission line that consists of an ideal source, a 50 ohm impedance, a 100 ohm impedance, and a 100 ohm terminator. The material is the same. You send a pulse down the line. When the pulse hits the impedance mismatch, you get a smaller reflection back, and a pulse...
  45. B

    Determine transmission of light through silver.

    Homework Statement The complex index of refraction of silver at 532 nm is \tilde{n} = 0.13 + 3.19i. What is the transmission for this light through a layer of silver that is one wavelength (in the medium) thick? In this problem, don't worry about reflections from the boundaries, just consider...
  46. Y

    Question on TEM wave travel in parallel plate transmission line.

    I want to confirm that the TEM wave is actually travel inside the dielectric between the two plates of the parallel plate transmission line. So even though surface current and surface charge appeared on the surface of the conductor plates as the consequence of the boundary conditions between the...
  47. J

    Transmission Spectrum- Absolute units?

    Homework Statement In manipulating transmission spectrum data from GaAs and InP I'm told to "Look up the refractive indices of GaAs and InP in the region of  = 1.0 micron, and use these to correct your experimental data for reflective losses and plot the corrected transmission T’ in...
  48. G

    HVDC Link Ratings for 400 kV Busbars?

    I have been using etap 7.5 demo and have been trying to model an HVDC link connected to 2 buses and conduct a load flow analysis (there is also a generator in swing mode attached to one bus and a normal transmission line connecting the two buses to satisfy the simulation requirements), but it...
  49. G

    Wireless transmission of electricity?

    Is it physically conceivable the possibility of transmitting electricity between spatially separated objects (e.g. a few meters) in a wireless way?
  50. B

    Marconi heard a transmission prior to transmitters invented?

    There's this internet rumor I came across where marconi heard a transmission before transmitters were invented? Some theorists (lets go easy on them please) beleive that - Marconi wasn't the first to invent the radio - but one of the few civilian inventors to come across it. Does...
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