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  1. 2 likes
    Free, cost $10 - funny. I have a few versions of Free CAD that was actually free. I wonder if the later versions are now sold.
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    With regard to materials, you must stay away from most metals, and especially aluminium. They will corrode rapidly in a salt water environment and lose strength accordingly. Think more of polyesters and epoxy materials. Are we to understand that rotation is in a horizontal or vertical plane? Assuming a horizontal plane for the rotation, you will need an airfoil shape, as the turning force is developed by hydrodynamic forces. Where will you generate power, below the water or above? This is a difficult problem, one that I worked on for the US Navy some years ago. You have a lot of hurdles to face to get this to work. DrD
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    Is P the number of planets, or the number of teeth on a planet gear? If it is the number of planets, I don't think it is true at all; at least, I do not see it. DrD PS: Remember that, for gears that actually mesh, the number of teeth on the two gears are each proportional to the pitch radii of the gears.
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    I"m glad to hear that you found something useful, Tim. It is almost comic that the name is FreeCAD, but it costs $10. I wonder what it would cost if it were called PayForItCAD? DrD
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    Dr. D hit it on the head. The big corps are alluring but a small company with design and fabrication functions will be worth much to you. Do everything you can to talk to every department and visit if allowed. Ask the members in each department what they wish the other departments knew. Don't try to fix the company in a one month internship but use the information in your work and in your professional role. Many problems are not unique once you get to the core. But are allowed to remain and erode time and profits.
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    Look for an opportunity in a company that actually manufactures some product. Such an employer will usually lket you see the whole process, from design, through manufacturing engineering, to sales and service. This is particularly valuable for a student. Do not go to a company that only does paper studies or the like; this is not the whole picture. DrD
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    7 examples of clutch application in automobiles:- Friction Clutch between engine and drive-train to engage-disengage power supply to drive-train as and when required and to allow engine to idle when vehicle is stopped. (Further interesting application format: Dual clutches) Dog Clutch in constant mesh gearbox to engage-disengage gears. (Manual transmission vehicles) Overrunning clutch in automatic transmissions to engage-disengage overdrive. (Automatic transmission vehicles) Lock-up clutch in torque converters to lock the torque converter above certain speeds to minimize losses. (Automatic transmission vehicles) Clutch to start-stop air conditioning systems's compressor. Clutches for Electronic Traction Control in certain high-end (by Indian Standards) automobiles. Clutches to transition between 2WD and 4WD (4-Wheel Drive). Think of all those machines that require intermittent power transmission from a continuous power supply, or have more than one power trains. Clutches are bound to be used in them. For example:- Farm equipment, machine tools, any type of engine (tank, ship, helicopter, submarine, etc.). The list could go on. Now, all these systems also need brakes. cause they have a drive shaft that needs stopping at some point or the other. EXTRA: One extremely high performance clutch is used in the F-35B JSF. This is a 5th generation fighter jet being built by NATO countries. The clutch is used to disengage-engage power supply to the lift fan from the turbine of the main engine. The lift fan enables the F-35B to land and take-off vertically (like a helicopter). The clutch presently being used wears out and needs a replacement in just 9 vertical take-offs !!!
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    Think this thing though for a minute. 1. There is no perfect total vacuum. A total vacuum would require the removal of all matter in the space, and this is simply not possible. No matter how hard we try, there are always a few molecules that remain. 2. Anything that will change the pressure of a gas will change the pressure of a partial vacuum. Thus the addition/removal of heat or a change in volume are the obvious ways to change the pressure in the (partially) evacuated space. DrD
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    Mechanical movement mechanism.., Five_hundred_and_seven_mechanical_moveme.pdf
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    Can anyone suggest me for the best wapsite for tutorial & drawing for desing with autocad/solidwork
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    Both DrD and Edgardo have important information to add to this discussion however, they have only discussed a part of the answwer. I believe that they have spoken about relevant points for discussion. Here are my thoughts. The larger diameter wheels on the rear of the tractor deliver a far greater contact patch, due to the tangent ratio to be able to successfully deliver the enormous torque generated by the engine and drive line combination. Engineer John
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    What I meant was the wheel assembly will adjust itself when it comes on a curved track from a straight one.. Thanks for sharing your input Dr D.
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    Sajal, please explain the phrase, "This helps to man over the axle assembly ...." I don't know quite what this means. As I stated before, there is no single cone that will be appropriate to all track radii. Try rolling a cone with a very wide apex angle; it will roll in a fairly small circle. Then roll a cone with a very small apex angle; it will roll in a very large circle. There is no single cone that will fit perfectly for all situation. Thus, while the cone helps, it is not a complete fix. It improves the situation, but there is still some sliding in most curves. DrD
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    I agree with Mr Reid .Machining of wheel outside diameter with a taper profile eliminates need of differential in rail wagon.This taper has got a direct relationship with curvature of the rail track.Also,the final machining of wheel outside diameter is accomplished with fine grinding operation.This helps to man over the axle assembly to slide left or right depending upon left or right turn.When the car takes a left turn,wheel on left track has to travel less distance than the right one hence the smaller diameter area of the left wheel will be in contact with the track.Similarly,right side larger diameter of wheel will be active so that right side wheel can travel more distance.
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    Mr. Reid is correct in regard to the conical shape of the wheels, but there is no single cone that will be correct for all track radii. Thus this is simply one of the several things done to relieve the sliding resulting from both wheels being rigidly attached to the axle. There are many ways to achieve a shrink fit, but none of them have any bearing on the question at hand. Would you please explain the word "outwith" as used in your final sentence. I am not familiar with this word, and not quite sure I know what it means, although I think I understand the intent of your sentence. I had not heard of the oilers mentioned by JAG, but this certainly makes sense if the sliding is a sufficiently great problem. DrD
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    The reason there is no differential on a train is the wheels are taperred with an anti-derailling stop (the larger diameter lip). When the train goes around the corner, the larger diameter of the wheel moves to the outside of the outside rail, resulting in the greater distance of the outer rail being "absorbed" by the greater diameter of the wheel that is in contact....similarly the smaller diameter of the inner wheel covers less distance. The angles are such that the appropriate diameters are self correcting, therefore there is no additional need for any form of differential. For reference, the wheels are normally an interference fit on the axle facilitated by either "hot wheel fitting" or "cold axle fitting". Any screaching is where the bend in the track is too tight for the particular wheel profile and therefore outwith this "self-correcting" zone of contact.
  18. 1 like
    That is correct solid axle to wheel mounting. I learned that in some situations on very tight curves there are oiler units that lubricate the side of the track to reduce the friction. Train wheels are allowed significant wear on the diameter. I don't think you could replace just one wheel.
  19. 1 like
    David is correct; the differential distance in rounding a curve is taken up in wheel slippage. This is one reason why we hear train wheels screech when rounding a curve. In any event, there would be no need for a differential; the wheels of a train car (other than the engine) are not driven. The difference could be taken into account by simply mounting the wheels with bearings between them and the axle. As far as i know, this is not done. I have seen large numbers of replacement wheel sets, two wheels rigidly mounted on a common axle, but never any indication that there was a bearing between the wheel and the axle. DrD
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    In ci engines, as we know that when the mixing of fuel and air is not very homogeneous as compared to si engines, the pressure rise is also not uniform. Due to this, the combustion takes place non-uniformly at many places at the time of ignition, and when more than two flames are generated on two different sites in piston cylinder, they follow the knock phenomena.
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    Introduction to operation management Introduction_to_operation_management.ppt
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    There are three basic power steering systems in use today – i) Hydraulic, ii) Electro-Hydraulic and iii) All Electric. As they say, there are no free lunches in this world. All the three eventually derive their power input requirements ultimately from the Engine, either being directly powered off its Crankshaft OR the Car Battery/Alternator. Of the three, The Hydraulic one is the most time-tested and Popular, as it can be applied from a Small Car to a Giant Earth Mover. However, by virtue of the nature of its design, it’s more maintenance prone and a little less energy-efficient. On the other hand, an All Electric ones presently have their application limited to Passenger Cars – weighing, say, from 750 kgs to 1500 kgs or so. This is coz it primarily depends on the Car’s Battery to Power it, which in turn depends on the Engine driven Alternator to charge it back. Since it can be ‘Computer Assisted’, it can very easily be programmed to any desired ‘spectrum’ of ‘Assist’. Since there are fewer moving parts in it and can be virtually made ‘idle’ at straight cruise conditions, it’s more ‘direct’ and Energy Efficient. An Electro-Hydraulic System is a ‘cross’ between the two, by way of advantages and disadvantages and doesn’t seem to be much popular these days, presumably from initial cost considerations
  23. 1 like
    you should opt for catia or ug nx these two are latest 3d modelling software.. and pro e and others are somehow little older softwares.