# Tag Info

42

If you consider only the static forces then indeed the thickness might seem over-engineered. However, engine blocks are not statically loaded. They operate in the range of a few hundred to a few thousand rpm (Revolution Per Minute), so there are dynamic considerations here. Fatigue When materials are subjected to cyclic loading they exhibit a reduction in ...

36

The soft clicking sound you hear when coasting is the pawl going over the ratchet as in the picture below.

26

it is called a freewheel. Inside the sprocket gear, there is a mechanism that lets the chain engage the rear wheel only when it is moving faster than the wheel is turning; else the wheel will turn freely. They are either several spring-loaded ballbearings that self deploy when the outer ring turns faster and recoil when it turns slower than the inner ring. ...

24

The photo you have is not for the standard jigsaw blade. Standard blades teeth point upward and cut upward for the obvious reasons: less wobble, more control, center of force near the handle. This is a revers cut blade designed to cut on downstroke to cut laminated work like countertops, so that the cut is not going to splinter the Formica or other laminate ...

23

Different gears have different drivers for having holes. One way you can categorize gears is by whether they are used primarily for transferring: motion: transferring angular position and angular velocity (see clockwork) torque: when the gears are used in power transmission Motion Gears that transfer motion don't need to transfer power. So their strength ...

21

For a large and/or high speed fan, there are several mechanical disadvantages, for example The outer ring is highly stressed and therefore heavy. It may also need a heavy containment system to avoid collateral damage if it breaks. For example in a large turbofan jet engine, a mechanical failure caused by a crack near the hub of the fan usually only releases ...

17

Once the cylinder is released and starts to accelerate downward, the rotating flyweights should pivot upwards to a certain degree (as shown in the drawing) and should act as a drag on each of the motors' rotor shafts and thus a drag on the falling cylinder No, there is no reason for them to pivot upwards. The gravity pulls the flyweights with the same ...

16

If you think what happens as each tooth cuts material then the blade is put into tension as it cuts, this means that the blade is likely to stay straight, but any unevenness between the teeth side to side may cause drift. If the blade cuts on the downstroke it will buckle as it is relatively thin for its length. A blade designed to cut on the downstroke ...

16

You need to consider that the complete engine block has to withstand the reciprocating forces generated by each of the pistons and con rods moving as well as the rotational forces from the rotating crankshaft. The 1 litre 4 cylinder engine used in the Hillman imp was known for twisting under load especially once it was tuned as it was an aluminium block. One ...

15

Most helicopters of modern manufacture are dynamically unstable while hovering- they require constant, "hands-on" control inputs from the pilot to keep things in balance. This task is very demanding and requires a lot of practice to master. Hiller helicopters (which have been out of production for many years) were one of the rare examples of ...

12

It really depends on the problem and what you want to capture. Usually, in classes, it may be beneficial for the students at an initial stage to disregard gravity alltogether in order to simplify the equations of motion. Below are a few scenarios, starting from the most trivial. Horizontal Case In the following mass spring system: There is no point in ...

12

The vibration, loading, and fatigue aspects have already been addressed, but a wide range of operating temperatures is another factor. A typical consumer engine can be deployed in anything from say -50F to 120F (-45C to 50C), and some blocks will crack when operated or even stored at those extremes. An engine operating at those extremes will experience ...

11

To add just a little to the answer from Mahendra Gunawardena, that device contains an electromagnetic coil and nearby a piece of iron that is connected to a valve mechanism. When electricity is sent to the coil, it becomes a magnet and draws the iron bit towards it. This opens the valve, and water can flow. A spring is furnished in the mechanism so that when ...

11

To enlarge slightly upon Solar Mike's response, a jigsaw that cuts on the upstroke tends to yank the saw shoe down into firm contact with the workpiece. This guarantees that the cut angle will match the shoe angle; for a shoe angle of 90 degrees this means a nice square cut.

9

Basically several ratchets, below animation shows when you are not pedalling. In the other direction the ratchet will engage and provide force. If you lift a bike and get the wheel spinning or just leading the bike, sometimes the pedals will turn very slowly due to the friction of ratchets. Image borrowed from https://www.notubes.com/technology/neo-...

9

I 'll start with the one that you should DEFINITELY NOT use: $mm^3$ or $mm3$. Probably the most widely used is the 1st. It's compact and economical and these are two of the most deciding factors in Engineering thought and practice. To take the point one step further, if it's in an engineering drawing you don't even need to put units in. Unless, its ...

9

The tension on the rope is everywhere the same and its equal to F. So if you did a free body diagram on the following system by sectioning along the ropes: what you get from the equilibrium is $4F = 48[N]$. I hope that is sufficient as an explanation, I tend to find that problems with pulleys can have different configurations and as such it is always ...

9

The ISO metric bolt has its diameter as the numeral part of the name. So M8 has a diameter of 8mm compared to that of the M4 bolt. So far scaling would make sense. However, the pitch of them is not proportional and would be wrong if you scale them. her is a figure from Wikipedia. Wiki .

8

Shame on the physics SE for closing it. No tacking required, although it is optional. The vessel is going directly down wind, not up wind. There is a factor called the speed ratio (SR), which is the boat speed divided by the true wind speed (TWS). TWS is the scalar difference between the wind velocity and water water velocity. And there is the associated ...

8

Best solution is: have and use the proper safety gear including the trousers (these are designed to catch the chain before they get to your skin and they work), helmet with face shield and safety boots. maintain bar, chain and sprockets correctly. I have used chainsaws for the last 40 years and at one time I have 4 of various sizes. I also sharpen my ...

8

In addition to the other answers such as weight reduction and inertia, there are other possibilities: Often there can be a precision machined hole for timing purposes. A common solution for some / many internal combustion engines to get camshafts timed to the crankshaft. Of course, dial gauges may also be used. Also, there can be threaded holes to help with ...

7

Relatively low lifting requirements (100 kg) Relatively fast lifting speed (80 fpm -> .4 m/s) The first part of your power calculation was wrong. There's no need to go into pulley diameters at this early stage of the calculation. Let's start at the load hook. 100 kg ~ 1 kN. Speed > 0.4 m/s. So power > 400 Watts. That's mechanical power, after a ...

7

The device in picture most likely is a monostable solenoid valve. A controller will command to open the valve for a specific duration. The design makes an assumption that there is sufficient water line pressure. The duration determines the amount of water or cleaning solution that is dispensed. Note: If the water line pressure drops, most modern day washing ...

7

Another solution in this case might be to get a new button that you can mount on the panel and then use extension wires to solder/connect it to the pins of the reset button. I'm mainly proposing this, because you seem quite confident with the electronic side of things.

7

It could be for combination of reasons. lubrication: the holes will both pump and let the lubricant pass through. Reduced angular momentum reduces backlash and adds to gearbox responsiveness. Lighter gears need less shaft support, helping the averall compactness of the gearbox.

7

Fans like the one on the right exist. These where first invented as rim-driven thrusters (rim driven is your search term, not centerless) for marine applications. The rim is the rotor of the electric motor driving the fans, the shroud around the rim contains the stator. With the amount of research I'm willing to do right now, I found no definitive statement ...

6

This is a type of barrel cam, but also resembles a bayonet mount. Barrel cams consist of a cylindrical surface with a slot or raised ridge that wraps around the curved surface. As the cylinder rotates, the cam follower (in your case, the arms on the T-shaft) rides through the grooves, moving up and down along the length of the cylinder. Barrel cams are ...

6

It approximately means it is allowed or forbidden to have scratches at the place of round. When you are making cylinder surface you can to do it many different ways: milling, welding, soldering. In one case must be strong requriment for smoothness of surface (for example in bearings need to minimize friction). In other cases it is allowed to have scratches (...

6

Some of this depends on how tough the dishes are. While taking a lot of room, I can see possibilitiles in a conveyer sorter. Concept one: Dishes are dumped onto a conveyer that is on a sideways slant. Operator initially only has to see that they are one layer deep. Use of multiple belts runing side by side at different speeds and textures may be able to ...

6

Your mechanism is going to lock up like the old car jacks immediately, due to differential raising of the platform. I am sorry but it looks like a textbook example of what not to do. in most real-life cases where the lifting actuator has to be off-center, they use a linked pair of scissors mechanism, like what they do in trucks' gate lifter, or the hydraulic ...

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