New answers tagged

1

reciprocating pumps require lubrication, which inevitably injects oil mist into the outflow. This then has to be filtered out before the air enters the cabin. With a centrifugal compressor/blower, there is no oil mist in the airflow and no need for a demisting filter.


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I expect it is the capacity , large building AC units are also radial or axial ; smaller units are recips. And as commented , likely there is a weight advantage.


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The primary shoe is normally operated directly by the piston and the secondary one by the cylinder sliding in the back plate. But this varies widely as there are versions using one cylinder with two pistons and others with two separate cylinders and pistons where both shoes are leading instead of having one leading and one trailing, twin leading shoe brakes ...


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The chief problem is that your batteries are just 84 W each (7x12). Your motors may be rated at 250W, but that will be 250 Watt mechanical. Electrically, they appear to use 336 W (24x14). That means you need exactly 4 batteries per motor, in a 2x2 configuration. Your current configuration lacks 14 batteries. I guess you see why Tesla uses lithium batteries. ...


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As I understand you want: a coplanarity of the two surfaces a location of the slot base I think you need something inline with this: Note that the datum A is identified by using an indicator under the callout. A-B could equally be used with the same meaning if you identify the two surfaces. You can have more explanation in ASME 14.5:2018 figure 6-6.


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In ASME Y14.5:2018 5.16.2, the term reversal is used in the definition of CR: The part surface shall be a fair curve without reversals. The term is not defined. It probably means that the curvature sign (measured in 'some' plane) doesn't change as figure shows. For your information, in ISO GPS ('Geometrical Product Specification') tolerancing, the ...


1

To fully answer we need a diagram of how this pump will be connected to the water company. I will speculate on a few configurations: If the city water flows into a bucket at atmospheric pressure, and the pump pulls out of that bucket, it will just be limited to the performance of the pump as expected. If the city water flows into the inlet of this pump; the ...


2

This is not an answer, it is just pointing out an error in calculations. DC motor torque discrepancy A DC motor at 2750[rpm] and 250[W], outputs $$M=\frac{P}{\omega} = \frac{P}{\frac{2\cdot\pi\cdot n}{60}} = 60\frac{P}{2\cdot\pi\cdot n} =0.8681 Nm$$ So your torque after the sprockets (if you are increasing the speed) is even less, probablyt around .5Nm. ...


1

Doesn't a boating cam cleat work in that fashion? Image source: Schaefer Marine. The harder the rope is pulled (to the left) the tighter the cleat bites it. If you can do the same with your friction pawl it too will lock onto the plunger even with wear over time. The other device that comes to mind is the Sprague or one-way clutch. Image source: SUMA ...


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The bending stiffness will be determined by the second moment of area ($I$). The formula you provide $\int\int r^2 da$ is for the Polar Moment of area ($J_p$), and is valid for torsional problems. Apart from little issue you are on the right track. Assuming that: x is the horizontal axis y is the vertical axis then you are after $I_{xx}$. Additionall, I'm ...


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I think you have two questions here, "Is there a difference in the stress concentration of a hole in an infinite thin plate loaded in biaxial tension vs biaxial compression?" "What happens during biaxial compression?" The first question: No, there is no difference between the biaxial and the uniaxial case. If you look at the equations, ...


4

Does anyone know if this would be a good idea? The proposed design has poor rigidity towards torsional loads. It doesn't matter whether the actuator is off-center or if the load is off-center: if load's center of gravity and actuator are not at the same position, the torsional load will likely damage the bearings. In your example with two guide rails, ...


5

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 ...


1

IMHO (and I guess you already know that), from a structural point of view putting 100 kg at 1/4[m] will create a huge amount of bending moment on a actuator that it is rated for 120[kg]. An although you don't clarify whether the actuator electric/hydraulic, if bearings are involved you are bound to get failure sooner rather than later. Normally this type of ...


0

You could also use something like they use on boats and planes for the doors. It's called a pantograph hinge.


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I am not familiar with Fluent too much (I use CFX), but you can specify inlet pressure and velocity unit vectors or angles. This way the direction of the flow and pressure are set. For example, in CFX for some simulations I specify inlet total pressure, inlet velocity unit vectors, and exit static pressure. This is one of the more "streamlined" ...


1

Very roughly, ignoring the nails or any twist in the angle of the blade, if your cutting cones are just two or three blades that cut the dirt basically acting as angled knives then the torque required is dispensed over all the length of the angle. In reality, the attack angle of the blades is twisting and the blades are of a spiral shape which makes it ...


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Given the test configuration and the test specimen dimensions I would suspect that the initial gradient slope is due to the gradual engagement of the test specimen. I.e. the material top and bottom surface will have a roughness associated with it. Something like in the following image. As a result when this is being compressed initially there is less area ...


2

As explained in https://electronics.stackexchange.com/a/521282/73158 it is a pressure switch. The resistance of the hose and shower head will cause the pressure to rise with increasing flow. As you have stated, "When there is fast water flow, it pushes the switch on the left of the round white part". Any ideas whether it needs certain pressure or ...


1

I don't have enough rep to reply to your comment on niels' post, but I would guess that another reason the heater only runs if the water flowrate is high enough is to avoid overheating the water. You definitely don't want to be boiling the water in the heater, and you don't want to scald someone washing their hands.


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If you plot pressure ratio vs air velocity at a constant speed of a compressor, you find that there is some peak pressure ratio, with a decrease if the the air velocity is increased or decreased. This peak pressure is the surge limit, the curve on the left of the chart. Pressure ratio decreases on either side of the maximum because turbine blades are ...


2

That is a pressure-sensitive switch. When there is water pressure in the system, it allows the heater circuit to be turned on. When there is no water pressure in the system, it prevents the heaters from being turned on. This prevents the heater from burning up, which it would if the heaters were on and there was no water flow in the system.


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Unless your wheels are skidding, they're in rolling contact. Use the rolling coefficient.


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Depends on the quality of your finished gear, both micro (surface finish) and macro (tooth runout, spacing, etc). Improper meshes will ultimately cause vibration in your system, if it's bad enough it will be pretty loud. Also, if you have an oversized tooth on your pinion and the mating tooth space on the gear is undersized you'll increase the stresses and ...


2

Google dugout aeration windmill system. There are various makers. Here's one: https://koenderswatersolutions.ca/ The compressor on them does one cycle per revolution of the windmill. While not as slow as 1 rpm the one I have is only rarely over 50 rpm. Internally they are a diaphragm pump. This means you only have the leaking of the valves to contend with....


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This is a typical graph for $C_L$ and $C_D$ with respect to angle of attack. As you can see, up to 30 degrees, $C_D$ increases very slowly, while $C_L$ reaches its maximum and then drops. So this is pretty standard. The ratio between $\frac{C_L}{C_D}$ can go from 10 to 50 depending on the specific airfoil that you use. So your simulation results seem to be ...


6

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.


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And the question you did not ask ;what about shape/crossection . That is, round and rectangular are both very common specimens .And rectangular with a curved crossection- full wall thickness pipe body. They also make very little if any difference. Note specifications often permit round tensile bars or full thickness tests with the same required mechanical ...


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Links: Geometric dimensioning and tolerancing. Datum reference.


1

The different mechanical properties for different sheet thicknesses has to do with grain refinement of the material during the rolling process. The following figures show what is happening to the old grain structure. The new elongated grain are the results of cold working. It is possible through annealing to form new grains (with no bias in direction). The ...


1

Usually no. However, yes in a manner of speaking. No: Primarily both properties are material specific. Therefore, no there shouldn't be an effect of the geometry on either the yield or the tensile stress. yes : (*) A typical example where geometry appears to have an effect on yield and tensile stress is the effect of thickness of sheet of steels. Usually ...


1

If I am not mistaken this probaly refers to the tolerances (the lower and higher acceptable dimensions of the diameter of the circle). i.e. : minimum is 3.40mm, and maximum should be 3.53mm In your particular example you need 4 thru holes within the tolerances stated above [3.40, 3.53].


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To the suggestions given by Mehendra, I'd add to use only one motor, with pulleys to power both wheels. It's simpler and cheaper and it ensures that the two power wheels will operate at precisely the same speed, which may be a problem with two separate motors.


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You should design a cooling system according to the motor manual (this is just one I found, make sure you use the correct manual). Before you get into liquid cooling, make sure that the air cooling requirements cannot be satisfied. The motor doesn't perform any worse with air cooling, as long as you can meet the requirements. For the liquid cooling system, ...


0

A complicated solution would be an electromagnetic clutch; essentially a solenoid with a spring and a friction wheel. When it's powered, spring is compressed away from the friction wheel and desired pulley. Power is provided and the spring returns to it's unloaded position and engages friction wheel with the pulley. You would need a controller to manage ...


2

Tight or loose belts is one possibility, used on shaft drive to drills and lathes for years. Or consider the electromechanical clutch used on cars now to drive the ac compressors.


1

that is a scanner that converts the writing on the board into a digital file for remote sharing, and then erases the board. These devices use either a rack-and-pinion gear arrangement with the rack running along the top edge of the board, or a flexible cable-and-pulley system with an electric motor coupled to the pulley through a set of reduction gears. You ...


2

I recommend researching motor driver circuits. These motor drivers internal has a H-Bridge design and have both direct on of digital signal to manage both direction (forward, backwards) and stop. You will also need a micro controller to control the motor driver. Below is an example block diagram for you to visualize. Below are few good places to start ...


1

Yes. Repair kits are available. Also, there are small nitrogen gas canister kits to pump them up quickly.


2

Choke is usually just applied to starting fuel/air mix regulation for ICE engines, as far as I'm aware. Throttle is used to actively manage fluid flow while a device is operating. Dampers typically only refer to means of controlling air/exhaust flow in non-ICE, like power plants or HVAC systems. As in your definition a damper is usually just a movable plate ...


1

There are already comercial products like this. They exist primarily in the asian market. They usually consist of a vertical machine which moves along a rail at the top and bottom of the board. There are two common approaches: Water Vacuum The water approach is what most would be familliar with. It has been used for ages with the usual handheld sponge. ...


2

In college I was in a group that actually attempted to solve this exact issue for a design class. A pill dispenser with different reservoirs for each medication and an arduino programmed to dispense set quantities of each pill at specified times with a loud alarm that is impossible to ignore. The challenge is in mechanically dispensing individual pills of ...


1

A common approach in residential areas where I live is to occasionally move a lane a car width towards the edge of the road every few thousand feet then back, with a small median and curb between the lanes. Essentially creating a slalom run. Probably not ideal in congested urban areas as it uses 1.5 times the space for the road but useful in suburban/rural ...


2

There is a simple reason and a useful added benefit. As you compress air of a fixed mass it occupies less volume. If you give it more space again, it will immediatly decompress and the multiple stages become useless. If you give it just enough space to occupy at its current pressure, the air will compress further. You could reduce space by reducing the ...


0

I would install a drag rake under the front end of the mower to snag the string before it gets into the blades. Failing that, I would replace the bearing with one that has a metal shield that won't melt like the urethane or neoprene shields will. Also consider inspecting the mowed area for string before starting the job. it might take your assistant an hour ...


7

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 ...


4

Budweiser made some design modification to regain its marketing and branding endeavours which had seen huge decline in sales threatening Budweiser's status as America's Best selling beer. The new design emphasized the iconic bowtie and updated its appearance giving it a eye-catching look, providing good holding experience which was easy to grip. After can ...


1

I think that neither of your solutions is correct. a) you are assuming that the volumetric strain is zero. However, if there is a change of volume then the volumetric strain can never be zero. Also, in that scenario, I am a bit uncertain what is $\varepsilon_d$. Is it deviatoric strain or is it strain perpendicular to the longitudical direction and due to ...


4

probably not, here is why. the coanda effect describes how a moving mass of air entrains nearby air and sets it in motion. So if we start with an extremely fast-moving but small jet of air, with it we can urge a much larger mass of air into motion. However, energy conservation dictates that the kinetic energy of the large mass of air set into motion be less ...


2

A merchandise container design is a fusion of art, marketing, branding, nudging public opinion, and many more factors. This design is bold, exciting, and stands out from the shelf in the store to when you hold it in your hand to when you discard it. It has been so successful that has made its way here even. Seems they have surmounted the manufacturing ...


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