Mechanical Engineering

When you lift an object, three things happen:

1) The lower extremities take on the weight of both your body and the object being lifted, and..

2) Your center of gravity is offset in front since you must lift the object in front of your body. This forces you to compensate using a change in posture, making more muscles work to lift. (Think of how long you can stand straight, verses how long you can stay in a stooped position.)

3) Since your hands are extended, this essentially uses your hands as a lever against you. (Take a weight, and lift it close to your body and compare it with lifting it with your arm straight out.. you will feel the difference!)

For instance, if I lift a large box, I need to extend my hands at least to the center of the box. My arms are acting as a lever, and my center of balance is moved forward. This places added strain on my body. My legs have also taken on the extra weight of the box.

Pulleys essentially redirect force along the path of the rope. This allows the force to be placed in a way that is easiest for our bodies to apply.

If I use a pulley, my legs are actually under less strain. Also, since I can pull the rope close to my body, the weight is not levered against me, and my center of gravity is only altered minimally. I can then use my body in its most efficient manner to exert the force required to lift the box.

A lathe is a woodworking or metal working machine that rapidly turns the item to be lathed, A blade is then brought to the item in the case of wood a chisel can be used by hand and in the case of metal the blade is held in a specially made jig , the blade slices away metal until the round shape required is acquired. An example of an item that can be made on a lathe is a Baseball bat.

The load current is made to flow through the thermal overload relay, which is actually a bimetalic strip. Beyond a prespecified current the bimetalic strip tend to deflect due to heat (thermal effect) thus cutting off the circuit and hence it acts as an over load relay protection.

Robert Hutchings Goddard was an American professor, physicist, and inventor who is credited with creating and building the world's first liquid-fueled rocket, which he successfully launched on March 16, 1926

When a cold object and a hot object are in direct contact (touching) heat will be transferred through thermal conduction.

Normally, heat transfer processes are categorized as thermal conduction, radiative transfer or convection.

Heat transfer through thermal conduction is the direct transfer of kinetic energy from one molecule to the nearby molecules. Because temperature is directly proportional to kinetic energy, interactions between neighboring particles exchange energy and that exchange energy gradually works it way from the higher temperature regions to the lower temperature regions. The process of the temperature becoming the same is called thermal equilibration.

Convective heat transfer occurs in fluids. If a gas, liquid, or other fluid, changes in fluid density change the buoyancy and will cause fluid to flow (a process called convection) and the heat contained in the warmer fluid is transferred to a new location by the physical movement of the fluid.

Radiative transfer occurs when a hot object radiates electromagnetic energy. While the sun is an obvious source of electromagnetic energy, it is also generated in smaller amounts by any object. The hotter objects radiate more electromagnetic energy and the cooler objects absorb it. This radiative transfer is important but not as noticeable usually as the other two. It does occur between objects whether they are in direct contact or not, but is usually so small as not to be important of the objects are touching.

One of the most common types of gears is the Spur Gear. They are most round with teeth along the edging. Spur Gears are used in oscillating sprinklers or fans, windup clocks, washing machines and dyers.

Strains and sprains- mechanize movement of heavy items

Slips and falls- attention to walking surfaces

Caught in- machine guarding

Cumulative Trauma- engineer out repetitive awkward motion

Burns- separate worker from hot work, guard, PPE

Foreign object in eye- enclosed point of operation of machines, provide eye protection

Cuts- reduce handling of sharp items, gloves

Dermatitis from contact with chemicals- pick safer chemical, minimize worker exposure, provide protective clothing

Your biggest hazard? Poorly trained, poorly supervised workers.

A moving pivot is a pivot that moves

work both independently and in connection with each other

It varies. Firstly, it's only present in ferrittic steels like carbon steel, not in most kinds of stainless. Secondly, it depends on the grain size of the steel microstructure, with smaller grains giving a lower transition temperature. The third factor is alloying elements. Silicone and Nickel content tends to raise transition temperature.

With modern steels the transition temperature is about -60 degrees celcius. Older steels may have a transition temperature at room temperature, or, more often, at 0 or -10 degrees.

Machines which are used to lift a load are governed by the "Law of machines", which states that the effort to be applied on the machine (p) is related to the weight (w) which it can lift as - p = mw + c Where m and c are positive constants which are characteristics of the machine.

how many aircraft carrier does the usa have

The Lights, air conditioning, communication, and the coffee machine, Stove, Microwave and the fridge.

Imagine traveling on a hot summer night with no light's air conditioning communication and food. So thanks to Thomas Edison who invented electricity saved the world.

Will the valve DN, PN, respectively, what does this mean?

PN name (pressure nominal) on behalf of Nominal pressure

Units are MPa MPa

For example, is J41H-16C Nominal pressure 16Kgf/cm2

Per square centimeter pressure value MPa 16Kg count if the case is PN1.6MPa

The representative of the internal pipe diameter DN

Units are mm mm

DN50 example is the 50 mm

One of the few advantages was formation of the League of Nations and signing of treaties that brought peace to the region for an extended period of time. The war nonetheless caused greater harm than good, with great loss of human life and collapse of economies.

The unit hertz means "cycles per second" and is a measure of the frequency of variation of anything which changes during a set period of time, including electric current and voltage. Saying that a generator of electricity runs at 50 hertz means that its current and voltage changes regularly at a rate of 50 times per second. Saying that a generator of electricity runs at 60 hertz means that its current and voltage changes regularly at a rate of 60 times per second. The Hertz value can be changed on the generator by increasing or decreasing the speed (RPM) of the prime mover. The generator has a feed back unit that monitors the frequency and automatically applies more power to the prime mover if the load increases and the generator RPM starts to slow down. The reverse happens if the load drops off and the generator starts to speed up, the power to the prime mover will be reduced. On a diesel generator it is the fuel flow that is increased and decreased to keep the frequency at a constant value. On a water turbine it is the water flow that is increased and decreased to keep the frequency at a constant value.

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When the check valve failed to seat properly at the lower unit in our well, the reserve tank would drain down quickly and then the pump would run again and again and again, . . .

If you have a valve between the pump outlet and the tank you can turn it off to check operation of the tank. Most likely your valve has failed.

It did this very often until we had the entire mechanism in the well replaced and installed a submersible pump.

No problems since and the submersible pump is hardly audible compared to the old pump motor which was mouted near the well head in the basement.

Good luck. Bob Jarnutowski bobjarn (at) hotmail.com

Ans 2 - A deep well pump does not have a'foot valve' -they are only on a jet pump. You have NOT told us the exact problem. If the bladder tank is not holding water then you may have a faulty check valve on top of your deep pump. Splits in the pumpdrop line down the well are also common. -The bladder in the tank can also be faulty. -You must tell us ALL symptoms , not just ask about two things you've heard names of.

Best solution - call a well tech , NOT a plumber !

The most commonly used hydraulic fluids are oils, so yes they are flammable. However, most any fluid COULD be used as a hydraulic fluid depending on the system design requirements. So it really depends on exactly what type of fluid is being used whether it is flammable or not.

Water is a "hydraulic fluid" and is not flammable.

Under NFPA standards, petroleum-based hydraulic fluids are not "flammable" if their flash point is above 100o F (37.8o C); they would be "combustible". NFPA 1 (2009): 3.3.153.2 Definition of Flammable Liquid

Products made from steel bars include many precision-engineered components that power hand tools

HDPE has higher density therefore it has greater tensile strength

A worm drive.

diesel

6.5 l/100km, or 43 mpg http://www.greencarcongress.com/2004/11/average_fuel_co.html