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Will_SPHS
Start date
Dec 30, 2015Tags
In summary, the conversation is about a high school engineering project to create a composting tumbler. The question is about the most efficient system to rotate the drum, with suggestions of using a gear system, sprocket and chain, or a piston. The conversation also discusses the material and power needed for the system, as well as safety considerations. Suggestions are made to look at electric cement mixers and to calculate the necessary torque and power for the system. The summary also includes a follow-up question about the weight and torque of the drum when full.
Will_SPHS
This is my first post on these forums, and I was hoping someone could answer a question I have. For my high school engineering course, we spend most of the year developing a solution to a problem of our choice. We are currently developing a composting tumbler that will turn automatically several times every other day. This is to ensure the quickest rate of composting based on factors such as aeration and microbial activity. A very simple 5 minute sketch below shows the basic design. There is a backup manual turning handle as well.My question pertains to the system that will be physically rotating the drum of the composer.I have very little knowledge of rotational systems, but after some research it appears that pulleys are relatively inefficient due to slipping and stretching. That leaves me with a gear systems or a sprocket and chain system. An additional idea that I had could involve a piston (I believe they are called linear actuators?) rotating the drum (shown below), but I don't know if that would be feasible.The drum is a hollow cylinder with relatively thins walls and a maximum weight of 600 lbs (when filled with wet dirt), although the lower density of compost would likely mean a much lower weight in the range of 300 - 350 lbs when full. There is an axle through the center of the cylinder. We are currently researching the material that is best suited to make the drum out of, but I wouldn't think that the material properties other than weight will have any impact on the turning of the drum.I apologize since this is a very broad question and I am ignorant on the subject, but I was hoping someone could suggest what specific gear system, sprocket and chain, piston, etc. to use.
Vedward
Consider a bicycle with gears and chains. No slippage here, unless the tire skids or slips on the road. Composite rubber belts do not pose any problems, these have been used for centuries on fans and engines. There usually is an adjustable idler to adjust the belt tension. There may be some slippage when first starting, but that will stop eventually. Many fans squeal when started for a short while until they are up to speed.
I won't tell you what to do, but plastics usually will work, steel drums have been used for this. Simple calculation of power needed is weight times radius of drum will give torque needed in units of force-length. This can be used to determine motor power.
Don't over think this, pulleys work fine to turn something. Your piston could be a steam engine or gas engine or air powered piston, but is more complex than a simple motor & pulley.
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If you fill the drum with sticky material the drum may have to rotate 90 degrees before the material falls to the bottom. My point is the torque required to rotate the drum to that position might be quite high. Perhaps several hundred foot pounds depending on the radius of the drum and the mass in it? The rate of rotation needed isn't very high so that suggests you are likely to have to gear down your motor quite a lot to reduce rpm and increase torque. I suspect the ratio required might be difficult to achieve with a single stage belt or chain drive? Needs further investigation.
Perhaps try making some assumptions about the maximum torque needed at the drum. Using that and the rpm (angular velocity) work out the power needed. Find a motor with perhaps double that power and using the motors nominal rpm work out the gear ratio required.
The high torque involved may make the machine a bit of a safety hazard - capable of cutting any fingers that get trapped or pulling hair or loose clothes into the mechanism so think about guarding and safety cut-off switches.
kcaldwel
It might be worth looking at electric cement mixers, which do a very similar job. They have them at Home Depot and Lowes. You might even be able to buy a drive system as a spare from one of them. The home versions appear to be fairly low-cost gear drive systems:There are some details of a nice enclosed gear drive system on an industrial grade unit here:A belt drive system could work - I think some of the old cement mixers were belt drive - but the they seem to have all gone to gear drive systems probably for low maintenance and safety reasons.
Will_SPHS
Thank you to everyone, your responses were all very helpful! It appears that we will be using a pulley or gear system. I will be doing the torque and power calculations to determine which one would work better. Also, we have definitely considered the different ways in which is would be a safety hazard, and have designed for that in our more advanced plans.
Will_SPHS
CWatters said:
If the combined drum and compost when full weighs anywhere from 425 - 500 lb (depending on the moisture content and the density of the compost), with a radius of 1', then the torque would just be 500 ft*lbs. With an angular velocity of 5 rpm (.52 rad/s), the power would be approximately 250 Watts.I was just wondering why you suggested a motor with double the calculated power. Would that most likely account for the frictional force between the drum and axle, or is that just the factor of safety? Does that mean you would suggest a motor closer to 1 HP (746 Watts) as opposed to a 1/2 HP (373 Watts), which were on the cement mixers linked by kcaldwel below you?Edit: I guess I don't really mean a "factor of safety", but a general range of power needed above what is predicted.
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Yes just a safety margin. For a one off project the cost of over rating the motor won't be great and will expend its life. If you were going to mass produce a million or something then the cost might be more critical and it might be worth measuring the actual power required.
Mentor
Insights Author
Startup will need more power as well.
If you need a single rotation several times per day, you can go for even lower speeds.
Mentor
And using the Freewheel feature of most bicycle final drives...Vedward said:
And using the Freewheel feature of most bicycle final drives...In most engineering optimizations, there is the opportunity to put some constraints on the final design that save a lot of cost or energy or whatever. I have several suggestions along those lines...** I would use a low-speed geared-down electric motor to turn the drum. You don't need it turned quickly, and the large gear ratio lowers the initial motor torque requirement.** I would use the above-mentioned free-wheel final drive arrangement (using standard bicycle components to lower cost), so that the human user can easily rotate the drum without having to disengage the geared-down electric motor assembly.** I would make it a requirement for users who were putting new material in the drum to manually rotate the drum a few times to even out the distribution of the material some, to lower the peak torque required on the geared-down motor assembly.So given those modifications, what peak electric motor torque do you calculate?
Mentor
Also, I would modify the drum to not be just an open cylinder. Can you picture what internal structure you could put in the drum to make it hold the material more evenly circumferentially?
Will_SPHS
We were planning on adding ridges, similar to those found in a dryer, so that the organic material wouldn't simply slide and stay at the bottom of the drum while turning. Is that what you mean, or am I talking about something else entirely? Also, does the freewheel mean that the user can simply turn the drum the opposite way of the motor without activating it or the gear system? I don't understand how they work, but if so that's really cool!berkeman said:
Also, I would modify the drum to not be just an open cylinder. Can you picture what internal structure you could put in the drum to make it hold the material more evenly circumferentially?
We were planning on adding ridges, similar to those found in a dryer, so that the organic material wouldn't simply slide and stay at the bottom of the drum while turning. Is that what you mean, or am I talking about something else entirely? Also, does the freewheel mean that the user can simply turn the drum the opposite way of the motor without activating it or the gear system? I don't understand how they work, but if so that's really cool!I suppose that with the lower-speed geared-down motor and with evenly distributed contents, we might be able to use a weaker (and cheaper) motor. Thank you for all your suggestions by the way!
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The manual rotation would actually be in the same direction as the motor.
SongDog
Used bicycle parts are cheap or even free at a small-town dump. You don't need high speeds, one or two rotations per day is a lot for composting. Keep the rotation rate that low and you can get by on just milliwatts with lots of mechanical advantage. Then you can use a small solar panel to drive it unattended.
Will_SPHS
We were originally planning on using a solar panel to power it, but we weren't sure whether it would produce enough power. It appears though that it would be fine in that regard. The main concern I would have with it now is that we are supposed to develop a solution that would be viable on the market (including having a cost similar or cheaper to existing solutions). Although it would of course be slightly more expensive due to being automated through the use of a motor, would a solar panel significantly drive up the cost if we theoretically produced them on a larger scale? I ask this with little knowledge of solar power, but I believe earlier research led us to believe they were fairly expensive.SongDog said:
We were originally planning on using a solar panel to power it, but we weren't sure whether it would produce enough power. It appears though that it would be fine in that regard. The main concern I would have with it now is that we are supposed to develop a solution that would be viable on the market (including having a cost similar or cheaper to existing solutions). Although it would of course be slightly more expensive due to being automated through the use of a motor, would a solar panel significantly drive up the cost if we theoretically produced them on a larger scale? I ask this with little knowledge of solar power, but I believe earlier research led us to believe they were fairly expensive.
Will_SPHS
Also, although using a very low amount of power has been suggested several times, wouldn't I need to use a substantial base amount of power to overcome the friction between the drum and the axle? I suppose we could use bearings to decrease the friction, but there would still be a substantial amount between the two metals.
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If you use decent bearings the friction will be low compared to the torque needed to lift and turn the material. I think your earlier calculation for the power 250w wasn't far out. You could easily measure the torque needed to manually rotate the drum.
Mentor
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Solar powered devices won't work well without sunshine, unless you want to add a battery, but that makes the whole system more complex.
Let's say one rotation per hour. Maximal torque is ~200 kg * g *30 cm = 600 Nm, therefore the drum needs a power of ~1 W purely for lifting mass (worst case). Even if we take losses to friction into account, that's a low power.
SongDog
mfb said:
Let's rather say one rotation per day. Haste makes waste. It's just a composter! Now we're looking at ~40 mW. This could easily be provided by one or two square inches of solar cell, perhaps scavenged from garden lighting. No need for a battery: if it only turns on sunny days, so what? Composting slows anyhow when there's less insolation and heating. Certainly no need of an AC extension cord, nor an outlet, nor of a massive motor.
Mentor
Insights Author
Now we just need an electric motor for such a low power (they exist in the 10 € range), and gears that reduce speed by 4-6 orders of magnitude.
Mentor
How about using an electrically-powered mechanical clock mechanism?
Will_SPHS
Thanks everyone for all of the help, I really appreciate it! The one problem with it turning extremely slowly however, is that the door/hatch to deposit material into may be stuck in a down position when the user wants to use it. They would then have to rotate it themselves anyway, defeating the whole purpose of the automation. I basically need it to turn when the user isn't putting things in it, and in an accessible position when they want to. It is aimed towards people who are relatively weak (the elderly, etc.), or people who want to compost without having to turn it themselves (which speeds up the composting process).
The solutions then that I thought of are:
- Have it turn during the night. An electrical cord or a solar panel charging a battery would have to be used.
- Have it turn quicker (not necessarily fast, just quick enough to reduce the likelihood that a user wants access while it is turning).
Will_SPHS
That is actually what we have been leaning towards recently.berkeman said:
How about using an electrically-powered mechanical clock mechanism?
That is actually what we have been leaning towards recently.
Mentor
Insights Author
You could have two or three doors.
Controlling the rotation (to have exactly a full one) will need some sensors or other additional logic.
SongDog
Will_SPHS said:
Just tilt the drum, like a cement mixer. Even 20-30 degrees tilt should do fine. Feed it from the raised end, not the side of the cylinder. Empty with a shovel from the same hole, or tip the whole thing back to dump it.
Will_SPHS
I was wondering how a freewheel would attach to the motor. Would it attach to the gearbox or the axle itself? I really appreciate the suggestion by the way, we will likely be using it.berkeman said:
https://en.wikipedia.org/wiki/Cogset#Freewheels
In most engineering optimizations, there is the opportunity to put some constraints on the final design that save a lot of cost or energy or whatever. I have several suggestions along those lines...
** I would use a low-speed geared-down electric motor to turn the drum. You don't need it turned quickly, and the large gear ratio lowers the initial motor torque requirement.
** I would use the above-mentioned free-wheel final drive arrangement (using standard bicycle components to lower cost), so that the human user can easily rotate the drum without having to disengage the geared-down electric motor assembly.And using the Freewheel feature of most bicycle final drives...In most engineering optimizations, there is the opportunity to put some constraints on the final design that save a lot of cost or energy or whatever. I have several suggestions along those lines...** I would use a low-speed geared-down electric motor to turn the drum. You don't need it turned quickly, and the large gear ratio lowers the initial motor torque requirement.** I would use the above-mentioned free-wheel final drive arrangement (using standard bicycle components to lower cost), so that the human user can easily rotate the drum without having to disengage the geared-down electric motor assembly.
I was wondering how a freewheel would attach to the motor. Would it attach to the gearbox or the axle itself? I really appreciate the suggestion by the way, we will likely be using it.
David Lewis
A scaled up grandfather clock mechanism might work. The disadvantage is that every few weeks an attendant would have to raise the weights again.
The most efficient type of motor for rotating a cylinder will depend on the specific requirements of the project. In general, stepper motors, servo motors, and DC motors are commonly used for rotating cylinderrotating cylinders. Each type has its own advantages and disadvantages, so it is important to consider factors such as torque, speed, precision, and cost when choosing the best motor for your application.
The ideal speed for rotating a cylinder will depend on the size and weight of the cylinder, as well as the desired rotation rate. To determine the ideal speed, you can use the formula: rotational speed (RPM) = (linear speed (m/s) x 60) / (2 x π x radius (m)). This will give you the rotational speed in revolutions per minute (RPM) for a given linear speed and radius.
This will depend on the specific requirements of your project. Direct drive systems are typically more efficient and have better precision, but they can be more expensive. Belt drive systems are generally less expensive and can provide greater flexibility in terms of speed and torque, but they may not be as precise. It is important to consider the specific needs of your project when deciding between direct and belt drive systems.
There are several ways to reduce energy consumption when rotating a cylinder using a motor. One way is to use a more efficient motor, such as a stepper motor or a brushless DC motor. Another way is to optimize the gear ratio of the motor to reduce the amount of energy required to rotate the cylinder. Additionally, using a variable speed drive can help to control the speed and energy consumption of the motor.
Yes, many motors have the ability to rotate in both clockwise and counterclockwise directions. For example, a stepper motor can be controlled to rotate in either direction by changing the sequence of electrical pulses. Other motors, such as DC motors, can be reversed by changing the polarity of the power supply. It is important to check the specifications of the motor to ensure it has the capability to rotate in both directions if that is a requirement for your project.
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Will_SPHS
Start date
Dec 30, 2015Tags
In summary, the conversation is about a high school engineering project to create a composting tumbler. The question is about the most efficient system to rotate the drum, with suggestions of using a gear system, sprocket and chain, or a piston. The conversation also discusses the material and power needed for the system, as well as safety considerations. Suggestions are made to look at electric cement mixers and to calculate the necessary torque and power for the system. The summary also includes a follow-up question about the weight and torque of the drum when full.
Will_SPHS
This is my first post on these forums, and I was hoping someone could answer a question I have. For my high school engineering course, we spend most of the year developing a solution to a problem of our choice. We are currently developing a composting tumbler that will turn automatically several times every other day. This is to ensure the quickest rate of composting based on factors such as aeration and microbial activity. A very simple 5 minute sketch below shows the basic design. There is a backup manual turning handle as well.My question pertains to the system that will be physically rotating the drum of the composer.I have very little knowledge of rotational systems, but after some research it appears that pulleys are relatively inefficient due to slipping and stretching. That leaves me with a gear systems or a sprocket and chain system. An additional idea that I had could involve a piston (I believe they are called linear actuators?) rotating the drum (shown below), but I don't know if that would be feasible.The drum is a hollow cylinder with relatively thins walls and a maximum weight of 600 lbs (when filled with wet dirt), although the lower density of compost would likely mean a much lower weight in the range of 300 - 350 lbs when full. There is an axle through the center of the cylinder. We are currently researching the material that is best suited to make the drum out of, but I wouldn't think that the material properties other than weight will have any impact on the turning of the drum.I apologize since this is a very broad question and I am ignorant on the subject, but I was hoping someone could suggest what specific gear system, sprocket and chain, piston, etc. to use.
Vedward
Consider a bicycle with gears and chains. No slippage here, unless the tire skids or slips on the road. Composite rubber belts do not pose any problems, these have been used for centuries on fans and engines. There usually is an adjustable idler to adjust the belt tension. There may be some slippage when first starting, but that will stop eventually. Many fans squeal when started for a short while until they are up to speed.
I won't tell you what to do, but plastics usually will work, steel drums have been used for this. Simple calculation of power needed is weight times radius of drum will give torque needed in units of force-length. This can be used to determine motor power.
Don't over think this, pulleys work fine to turn something. Your piston could be a steam engine or gas engine or air powered piston, but is more complex than a simple motor & pulley.
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If you fill the drum with sticky material the drum may have to rotate 90 degrees before the material falls to the bottom. My point is the torque required to rotate the drum to that position might be quite high. Perhaps several hundred foot pounds depending on the radius of the drum and the mass in it? The rate of rotation needed isn't very high so that suggests you are likely to have to gear down your motor quite a lot to reduce rpm and increase torque. I suspect the ratio required might be difficult to achieve with a single stage belt or chain drive? Needs further investigation.
Perhaps try making some assumptions about the maximum torque needed at the drum. Using that and the rpm (angular velocity) work out the power needed. Find a motor with perhaps double that power and using the motors nominal rpm work out the gear ratio required.
The high torque involved may make the machine a bit of a safety hazard - capable of cutting any fingers that get trapped or pulling hair or loose clothes into the mechanism so think about guarding and safety cut-off switches.
kcaldwel
It might be worth looking at electric cement mixers, which do a very similar job. They have them at Home Depot and Lowes. You might even be able to buy a drive system as a spare from one of them. The home versions appear to be fairly low-cost gear drive systems:There are some details of a nice enclosed gear drive system on an industrial grade unit here:A belt drive system could work - I think some of the old cement mixers were belt drive - but the they seem to have all gone to gear drive systems probably for low maintenance and safety reasons.
Will_SPHS
Thank you to everyone, your responses were all very helpful! It appears that we will be using a pulley or gear system. I will be doing the torque and power calculations to determine which one would work better. Also, we have definitely considered the different ways in which is would be a safety hazard, and have designed for that in our more advanced plans.
Will_SPHS
CWatters said:
If the combined drum and compost when full weighs anywhere from 425 - 500 lb (depending on the moisture content and the density of the compost), with a radius of 1', then the torque would just be 500 ft*lbs. With an angular velocity of 5 rpm (.52 rad/s), the power would be approximately 250 Watts.I was just wondering why you suggested a motor with double the calculated power. Would that most likely account for the frictional force between the drum and axle, or is that just the factor of safety? Does that mean you would suggest a motor closer to 1 HP (746 Watts) as opposed to a 1/2 HP (373 Watts), which were on the cement mixers linked by kcaldwel below you?Edit: I guess I don't really mean a "factor of safety", but a general range of power needed above what is predicted.
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Yes just a safety margin. For a one off project the cost of over rating the motor won't be great and will expend its life. If you were going to mass produce a million or something then the cost might be more critical and it might be worth measuring the actual power required.
Mentor
Insights Author
Startup will need more power as well.
If you need a single rotation several times per day, you can go for even lower speeds.
Mentor
And using the Freewheel feature of most bicycle final drives...Vedward said:
And using the Freewheel feature of most bicycle final drives...In most engineering optimizations, there is the opportunity to put some constraints on the final design that save a lot of cost or energy or whatever. I have several suggestions along those lines...** I would use a low-speed geared-down electric motor to turn the drum. You don't need it turned quickly, and the large gear ratio lowers the initial motor torque requirement.** I would use the above-mentioned free-wheel final drive arrangement (using standard bicycle components to lower cost), so that the human user can easily rotate the drum without having to disengage the geared-down electric motor assembly.** I would make it a requirement for users who were putting new material in the drum to manually rotate the drum a few times to even out the distribution of the material some, to lower the peak torque required on the geared-down motor assembly.So given those modifications, what peak electric motor torque do you calculate?
Mentor
Also, I would modify the drum to not be just an open cylinder. Can you picture what internal structure you could put in the drum to make it hold the material more evenly circumferentially?
Will_SPHS
We were planning on adding ridges, similar to those found in a dryer, so that the organic material wouldn't simply slide and stay at the bottom of the drum while turning. Is that what you mean, or am I talking about something else entirely? Also, does the freewheel mean that the user can simply turn the drum the opposite way of the motor without activating it or the gear system? I don't understand how they work, but if so that's really cool!berkeman said:
Also, I would modify the drum to not be just an open cylinder. Can you picture what internal structure you could put in the drum to make it hold the material more evenly circumferentially?
We were planning on adding ridges, similar to those found in a dryer, so that the organic material wouldn't simply slide and stay at the bottom of the drum while turning. Is that what you mean, or am I talking about something else entirely? Also, does the freewheel mean that the user can simply turn the drum the opposite way of the motor without activating it or the gear system? I don't understand how they work, but if so that's really cool!I suppose that with the lower-speed geared-down motor and with evenly distributed contents, we might be able to use a weaker (and cheaper) motor. Thank you for all your suggestions by the way!
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The manual rotation would actually be in the same direction as the motor.
SongDog
Used bicycle parts are cheap or even free at a small-town dump. You don't need high speeds, one or two rotations per day is a lot for composting. Keep the rotation rate that low and you can get by on just milliwatts with lots of mechanical advantage. Then you can use a small solar panel to drive it unattended.
Will_SPHS
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We were originally planning on using a solar panel to power it, but we weren't sure whether it would produce enough power. It appears though that it would be fine in that regard. The main concern I would have with it now is that we are supposed to develop a solution that would be viable on the market (including having a cost similar or cheaper to existing solutions). Although it would of course be slightly more expensive due to being automated through the use of a motor, would a solar panel significantly drive up the cost if we theoretically produced them on a larger scale? I ask this with little knowledge of solar power, but I believe earlier research led us to believe they were fairly expensive.SongDog said:
We were originally planning on using a solar panel to power it, but we weren't sure whether it would produce enough power. It appears though that it would be fine in that regard. The main concern I would have with it now is that we are supposed to develop a solution that would be viable on the market (including having a cost similar or cheaper to existing solutions). Although it would of course be slightly more expensive due to being automated through the use of a motor, would a solar panel significantly drive up the cost if we theoretically produced them on a larger scale? I ask this with little knowledge of solar power, but I believe earlier research led us to believe they were fairly expensive.
Will_SPHS
Also, although using a very low amount of power has been suggested several times, wouldn't I need to use a substantial base amount of power to overcome the friction between the drum and the axle? I suppose we could use bearings to decrease the friction, but there would still be a substantial amount between the two metals.
Science Advisor
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If you use decent bearings the friction will be low compared to the torque needed to lift and turn the material. I think your earlier calculation for the power 250w wasn't far out. You could easily measure the torque needed to manually rotate the drum.
Mentor
Insights Author
Solar powered devices won't work well without sunshine, unless you want to add a battery, but that makes the whole system more complex.
Let's say one rotation per hour. Maximal torque is ~200 kg * g *30 cm = 600 Nm, therefore the drum needs a power of ~1 W purely for lifting mass (worst case). Even if we take losses to friction into account, that's a low power.
SongDog
mfb said:
Let's rather say one rotation per day. Haste makes waste. It's just a composter! Now we're looking at ~40 mW. This could easily be provided by one or two square inches of solar cell, perhaps scavenged from garden lighting. No need for a battery: if it only turns on sunny days, so what? Composting slows anyhow when there's less insolation and heating. Certainly no need of an AC extension cord, nor an outlet, nor of a massive motor.
Mentor
Insights Author
Now we just need an electric motor for such a low power (they exist in the 10 € range), and gears that reduce speed by 4-6 orders of magnitude.
Mentor
How about using an electrically-powered mechanical clock mechanism?
Will_SPHS
Thanks everyone for all of the help, I really appreciate it! The one problem with it turning extremely slowly however, is that the door/hatch to deposit material into may be stuck in a down position when the user wants to use it. They would then have to rotate it themselves anyway, defeating the whole purpose of the automation. I basically need it to turn when the user isn't putting things in it, and in an accessible position when they want to. It is aimed towards people who are relatively weak (the elderly, etc.), or people who want to compost without having to turn it themselves (which speeds up the composting process).
The solutions then that I thought of are:
- Have it turn during the night. An electrical cord or a solar panel charging a battery would have to be used.
- Have it turn quicker (not necessarily fast, just quick enough to reduce the likelihood that a user wants access while it is turning).
Will_SPHS
That is actually what we have been leaning towards recently.berkeman said:
How about using an electrically-powered mechanical clock mechanism?
That is actually what we have been leaning towards recently.
Mentor
Insights Author
You could have two or three doors.
Controlling the rotation (to have exactly a full one) will need some sensors or other additional logic.
SongDog
Will_SPHS said:
Just tilt the drum, like a cement mixer. Even 20-30 degrees tilt should do fine. Feed it from the raised end, not the side of the cylinder. Empty with a shovel from the same hole, or tip the whole thing back to dump it.
Will_SPHS
I was wondering how a freewheel would attach to the motor. Would it attach to the gearbox or the axle itself? I really appreciate the suggestion by the way, we will likely be using it.berkeman said:
https://en.wikipedia.org/wiki/Cogset#Freewheels
In most engineering optimizations, there is the opportunity to put some constraints on the final design that save a lot of cost or energy or whatever. I have several suggestions along those lines...
** I would use a low-speed geared-down electric motor to turn the drum. You don't need it turned quickly, and the large gear ratio lowers the initial motor torque requirement.
** I would use the above-mentioned free-wheel final drive arrangement (using standard bicycle components to lower cost), so that the human user can easily rotate the drum without having to disengage the geared-down electric motor assembly.And using the Freewheel feature of most bicycle final drives...In most engineering optimizations, there is the opportunity to put some constraints on the final design that save a lot of cost or energy or whatever. I have several suggestions along those lines...** I would use a low-speed geared-down electric motor to turn the drum. You don't need it turned quickly, and the large gear ratio lowers the initial motor torque requirement.** I would use the above-mentioned free-wheel final drive arrangement (using standard bicycle components to lower cost), so that the human user can easily rotate the drum without having to disengage the geared-down electric motor assembly.
I was wondering how a freewheel would attach to the motor. Would it attach to the gearbox or the axle itself? I really appreciate the suggestion by the way, we will likely be using it.
David Lewis
A scaled up grandfather clock mechanism might work. The disadvantage is that every few weeks an attendant would have to raise the weights again.
The most efficient type of motor for rotating a cylinder will depend on the specific requirements of the project. In general, stepper motors, servo motors, and DC motors are commonly used for rotating cylinders. Each type has its own advantages and disadvantages, so it is important to consider factors such as torque, speed, precision, and cost when choosing the best motor for your application.
The ideal speed for rotating a cylinder will depend on the size and weight of the cylinder, as well as the desired rotation rate. To determine the ideal speed, you can use the formula: rotational speed (RPM) = (linear speed (m/s) x 60) / (2 x π x radius (m)). This will give you the rotational speed in revolutions per minute (RPM) for a given linear speed and radius.
This will depend on the specific requirements of your project. Direct drive systems are typically more efficient and have better precision, but they can be more expensive. Belt drive systems are generally less expensive and can provide greater flexibility in terms of speed and torque, but they may not be as precise. It is important to consider the specific needs of your project when deciding between direct and belt drive systems.
There are several ways to reduce energy consumption when rotating a cylinder using a motor. One way is to use a more efficient motor, such as a stepper motor or a brushless DC motor. Another way is to optimize the gear ratio of the motor to reduce the amount of energy required to rotate the cylinder. Additionally, using a variable speed drive can help to control the speed and energy consumption of the motor.
Yes, many motors have the ability to rotate in both clockwise and counterclockwise directions. For example, a stepper motor can be controlled to rotate in either direction by changing the sequence of electrical pulses. Other motors, such as DC motors, can be reversed by changing the polarity of the power supply. It is important to check the specifications of the motor to ensure it has the capability to rotate in both directions if that is a requirement for your project.
Choosing a lawnmower is easy, isn’t it? Surely, I only need to keep my lawn neat? But, do you want to keep your grass cut short or do you want to give your lawn the desired finish that you see on fields and at stadiums. The perfectly manicured lawn can be in your back garden with just the correct choice of lawnmower. So why should you choose a cylinder lawnmower over a rotary lawnmower?
A cylinder lawn mower has between 5 to 12 exposed blades at the front of the mower, rotating on a horizontal axis trapping & slicing the grass against a fixed bottom blade, in a scissor-like action.
A Rotary lawnmower has a cutting deck with rotating blades on a singular vertical pivot point. They cut your lawn with a fast – rotating chopping action, that in most cases tears and damages the grass leaves which prohibits new growth
Rotary machines may be the best option if you’re just looking to cut your lawn like everybody else, but if you want a beautifully presented lawn then you should choose a Cylinder Mower.
The quality of cut due to the slicing ‘scissor’ type action of the cylinder lawn mower, if maintained correctly, is superior to that of the ‘chopping’ or ‘smashing’ action of a rotary mower.
A cylinder mower cuts using a set of sharp rotating blades. The rotating cylinder traps the blades of grass between its spinning blades & a stationary bottom blade. This action results in a precise, scissor-like cut on the grass, that is less damaging to the grass leaves. Which in turn translates to a quicker recovery, increases water retention and minimises the risk of disease.
Lawn scalping refers to cutting your lawn grass quite low, so low that you expose the stems of your grass blades. Typically, scalping is done intentionally by setting the mower to its lowest height, but you can also accidentally scalp areas of the lawn.
The front & rear rollers of a cylinder mower run close to the point at which the grass is cut. This will allow for very low heights of cut without running the risk of accidentally scalping your lawn.
Soil compaction is the primary cause of an unhealthy lawn. When soil is compacted, the particles of soil are pressed so tightly together that the soil isn’t porous enough to hold water, oxygen, or other nutrients that it needs to thrive. Without these necessities, your grass becomes weak, often browning easily and turning visibly thinner.
The motion of the cylinder mower helps reduce soil compaction for an overall healthier turf. Each unit has a heavy rear roller instead of wheels, evenly dispersing weight across the unit rather than concentrated under the wheels, creating a smoother, less thatchy surface.
All high-quality cylinder mowers have substantial front & rear rollers, creating a strong, clear stripe. This is due to the quality of the precision-cut given by a cylinder mower. The attractive light & dark stripes created by a cylinder mower are recognized as being longer-lasting & more crisply-defined than those created by other mowers fitted with a rear roller alone.
Various cylinder mowers come with the added benefit of versatility. With one unit, you can essentially have multiple machines simply by changing out the reel for a variety of speciality reels, including scarifier, verticutter, groomer or sweeper. By establishing a best practice where reels are rotated during lawn care, you can establish a better root base with less thatch that allows for greater water & nutrient penetration & a significantly healthier turf.
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Now you have the perfect lawnmower that will prevent scalping. It is versatile offering precision cuts and quality stripes. But to create and maintain a manicured lawn comes with a few key principles of its own. Luckily we have you covered. It’s time to take your desired cylinder lawnmower and follow our 4 basic principles of lawncare {Link to this blog} to care for your lawn in the best way.
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