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Mechanical Engineering
Mechanical Engineering is a branch of engineering that encompasses the generation and application of heat and mechanical power and the design, production, and use of machines and tools. Mechanical engineering involves application of the principles of dynamics, control, thermodynamics and heat transfer, fluid mechanics, strength of materials, materials science, electronics, and mathematics.
10,989 Questions
Why did people turn aircraft propelers by hand?
To start the engine. Early propeller planes had no electric start system as we are accostomed to in automobiles. Turning the propeller to start the plane engine (a very dangerous task, by the way) was akin to roll-starting a car with a bad starter or solenoid. (That was a pretty common practice when cars were less reliable that way and mostly had manual transmissions). Also, then and now, the engine had to be turned to clear each cylinder and prime it with fuel. In the old aircraft, they would turn the engine with the "Swith Off" and then give a command "Swith On" to start it. Later aircraft, had a hand-crank to start the engine. Even aircraft as last as the WW2 Ju-87 Stuka used a hand-crank starter. Many of the early WW1 aircraft had Rotary Engines that were 7 or 9 cyclinders. These are NOT the same as Radial Engines. Rotary Engines were designed so that they rotated on a fixed shaft. The propellor was bolted to the engine and spun when the engine rotated. This meant that when a Cylinder was in one position, fuel was injected, it rotated to another position and it fired and another position it expelled the gasses. So, clearing the cylinders were important part of starting a Rotary Engine. If you can find a real movie clip of a REAL WW1 airplane, you can see the engine rotating. Even photos may show it blurred. Some aircraft with Rotary Engines were Fokker Eindecker, Fokker Dr.1 Triplane, Nieuport 11 & 17, and many of the Sopwith airplanes. See Link for a cool animation of a Rotary Engine. Notice that the Cylinders are attached at one point that is off-set from the center of the rotating engine block. These are notes from the film crew of the movie "Blue Max" for the in-line engine SE-5. Starting
Chocks in place and fire extinguishers at hand. Fuel cockON (Push on), throttle CLOSED, switches OFF. Pull ring at top, right hand side of instrument panel until ground crew confirm that fuel drips out of the carburetor overflow pipe below the cowling. Prime with one to two full strokes of the Kigas primer while the propeller is turned over. Do not over primeor you may start an intake fire.
Throttle set at half an inch OPEN, both switches ON and press the starter button.
After starting, check for normal oil pressure and warm up at 1000- 1200 r.p.m. for 5 minutes when cold. (Oil temperature may not register in this time) Stick hard back during run up. Check for a dead cut, normal static revs 2100. Select hot air (Turn T handle and pull) and check that the engine note changes or the r.p.m. drops indicating that the control is serviceable. Return the cold air. The acceptable magneto drop is 100 r.p.m. Check the oil pressure is normal and the slow running 6 - 700 r.p.m. Same source--but not very detailed. The cockpit layouts in the two aircraft have important differences. Both have fuel and oil cocks. The fuel and oil cocks should be switched OFFbetween flights to prevent flooding of the lower cylinders. Both switches can be used for starting. Hand swinging of these engines can be tricky and the ground over will probably call for the switches OFF between each movement of the propeller.
The engine should be thoroughly warmed up before run up or it may run rough at full throttle. The carburetor heat is permanently but relies on the engine being well warmed. The correct static r.p.m. for each machine is noted on the instrument panel. If this is not obtained the cause is usually both plugs in one cylinder are not firing. The engine will then appear to run normally with little or no mag. drop but the faulty cylinder will be cold to the touch.
What is the capacity of a safety valve?
The capacity of a safety valve refers to its ability to discharge a specific volume of fluid, typically steam or gas, at a designated pressure without exceeding the safety limits of a system. It is usually expressed in units such as pounds per hour (lb/hr) or cubic feet per minute (cfm). The capacity is determined by factors such as the valve size, the pressure setting, and the properties of the fluid being handled. Proper sizing is crucial to ensure that the safety valve can adequately protect the system from overpressure situations.
apron constant is inverse of transmission ratio of the feed rod pinion of apron box
What welding electrode is used for different metals?
Different metals require specific welding electrodes to ensure strong and effective joints. For instance, E6011 and E6013 electrodes are commonly used for welding mild steel, while E7018 is preferred for low-hydrogen welding applications. For stainless steel, E308L or E309L electrodes are often utilized, while aluminum welding typically employs ER4047 or ER5356 filler rods. The choice of electrode is crucial for achieving desired mechanical properties and corrosion resistance in the welded joint.
In flat rolling what is a screw down and a top roll balancing mechanism?
In a rolling mill, the screw down (usually electrically operated in big mills) is the mechanism for setting up the spacing between the rollers, called the roll gap. The top roll balancing mechanism is a mechanical (rods, springs) or hydraulic setup to hold the top roller up in contact with the screw down. The larger mills we see in operation have massive rollers, and they have considerable weight. The whole of the upper roll mechanism will be set in heavy chocks to to stabilize it and distribute the loads of the rolling operation. Additionally, we often see mills with backup rollers, and the top work roller and backup roller pair will be held in contact with the screw down by the top roll balancing mechanism. There is a bit more to this when we consider the dynamic operation of the biggest rolling mills, but the basics remain the same. The thickness of the product, the "indexing" of the roll gap, will be set by the screw down. And the the top roller is held up against the screw down by the top roll balancing mechanism.
What type of paper when made into a paper boat floats longest?
I would use wax paper because of all the different kinds of paper, its the least absorbant.
When reading the steel heat treatment notation RC what does the R mean?
RC stands for Rockwell Hardness C scale; the different letters A,B,C etc. are based on different loads and indenters for measurement. C scale is typical for steels, while B scale is typical for aluminum. There are conversion tables for these if needed.
The wedge is V shaped to make the shape of a wedge. The definition of a wedge is a gap between two spaces, thereby causing the V in wedge design. The v shape of the wedge was also used as a military strategy to break through enemy lines.
What is the difference between G code and M code in CNC programming?
Generally G codes are writen in and performed by the CNC processor and operate the motion control part of the control, the M codes are MACHINE codes, these operate most of the basic electrical control functions such as Coolant, Tool changers, safety circuits etc, the M,S & T codes are written in a separate PLC processor, both processors usually communicate with each other over a common bus.
The tool changer and spindle are both configured to suit a particular machine specifics.
This problem asks to solve for unknown forces when an object is in equilibrium. Let us solve it!
As platform is in equilibrium , so , by 1st condition of equilibrium,
Upward forces = Downward forces
T1+T2=600+300=900N ,
Now apply second condition,
Anti-clockwise torque= Clockwise torque
(taking point of first leg as axis of rotation so that torque due to T1 is zero)
300*2+T2*4=600*2
600-1200=-T2*4,
600=T2*4, or
T2=600/4=150N ,now
T1=90-T2=900-150=750N
How you can stop reverse rotation of cw pump?
Are you sure it's pumping in the wrong direction? It should be pulling water from the radiator through it's lower hose. Water will be returning to the radiator through the upper hose past the thermostat after it warms up. If your water is flowing the wrong direction and you have a mechanical pump ( one with a belt on it ) you will have to replace it. If you have a uni-belt setup (serpentine belt), it may be on incorrectly. If you have an electrical water pump ( probably aftermarket ) reverse the polarity on the power connection.
What is Equivalent Material for German Din'?
The German abbreviation DIN stands for Deutsche Industrie Norm, Equivalent international bodies are:
ASA - American Standards Association
BSA - British Standards Association
ISO - International Organisation for Standardisation
IEC - International Electrotechnical Organisation
1000cm
RUN!
The more efficient a machine is the closer the actual mechanical advantage is to the?
Perfect efficiency
How do you convert 100 meters to feet?
1 foot = 30.48 cm = 0.3048 meter
100 meters = 100/0.3048 feet
Direct Conversion Formula 100 m*
1 ft
0.3048 m
=
328.0839895 ft
What are the relation between tensile stress and shear stress and bearing stress?
Tensile Stress is approximately two times the shear stress.Relationship bet n Tensile Stress and bearing stress varies from application to application.It Depends on Various Factors.
Can an electrical starter turn without electricity?
No, an electrical starter can not turn without an electrical source.
What is Ultra-High-Strength Steel?
it is technically about 3 times more tensile than ordinary steel .therfore this steel becomes a ultra strenthenedsteel.
INFI steel is used by Busse Combat Knives. The performance of INFI in the blades of Busse Combat has been demonstrated live by jerry Busse at live and public demonstrations at knife shows, as well as in videos and pictures, these include thousands of push cuts on full once inch hemp rope without sharpening, cuts though a hanging bundle of 10 strands of inch hemp, multiple 2x4's chopped with the knife still shaving, and very heavy prying loads and bends to a very high degrees without breaking on a fully hardened blade.
INFI has: 0.5% carbon, 8.5% Chromium, 0.74% nickel, 0.36% vanadium 1.3% molybdenum 0.95% cobalt and 0.11% nitrogen. The rest is iron (obvious).
