Tasks followed up:
Company name: Crane-tacular solutions!
Calculations for grass-hopper design are in progress, getting close to a solution during meeting.
Winch preferances and weights established.
Preferred materials identified.
nb. density of steel 7800 kg/m^3
density of aluminium 2700 kg/m^3
Tasks for next meeting:
CAD analysis and drawings etc.
Finalised calculations
Costings for crane parts
Write proposed presentation for development with group at next meeting
Future meetings:
Monday 19/04/2010 - 10am Guild loft.
Attendees:
A. Compton
J. Collins
A. Daniels
R. Dhillon - Apologies given.
Thursday 25 March 2010
Wednesday 24 March 2010
Boom fixings and real mini crane pictures
This post will explore a few methods of fixings and boom development from original sources. The bulldog crane now named 'The Grasshopper' as of now, has to be marketable and innovative. I personally believe that idea number 3 looks like a grasshopper.
Slogans such as "Get the Hopper" and "I need help, I need The Grasshopper" are catchy and have a history of adding lasting appeal to a product and gives it a separate identity, a sort of quirky uniqueness.
Slogans such as "Get the Hopper" and "I need help, I need The Grasshopper" are catchy and have a history of adding lasting appeal to a product and gives it a separate identity, a sort of quirky uniqueness.
fig.1Above (fig.1) is a picture of a green grasshopper for visual aid. (Idea 3 will be shown at a later date.)
Now moving on to more serious matters...
Below is a crane, it uses a 'cradle' to move the object picked up in the x-direction. The object is picked up using chains and hooks, once secure it is elavated to the desired position.
fig.2
This is an excellent model for us to work from. We can use a inverted T beam for the boom itself. An 'I 'beam will work also but will add unnecessary weight, we will try to avoid it unless the stress calculations require the boom to have extra strength. Remebering idea 3 is supported from both ends and is not wall mounted as this one is therefore should be able to hold considerably more than 500kg.
fig.3
Figure 4. shows how the wheels that allow the cradle to move along the boom are fixed. The wheels are on both sides of the boom. They are fixed in place using a bracket that stops them from moving in unwanted directions or falling off. The wheels can be replaced and the entire cradle removed by unscrewing the bolts. This makes it a separate component from the boom, making it easier to transport.
fig. 4
Talking about portability, the boom will roughly be 4m+ so carrying this around either by man or machine power (landrover defender) is dfficult. So a 'hinge' is in order, and I have one that may suite our needs...wala!
fig.5
We can develop and modify this one to suite our needs. OR the two parts of the boom can be separate but connected with bolts.
Heavy duty materials must be used and an accurate stress test is required to determine most of the positioning of the components and type of fixing required.
These photos are property of Amardeep Singh Dhillon and can only be used with permission from the owner, me.
Monday 22 March 2010
Types of electric winch:
Winch example (1)
Found: http://www.liftingonline.com.au/products/JDN6031000KG X 3M, JDN 'MINI' AIR HOIST
Specifications: (Extensive specifications given in a table on the link above)
"1000KG X 3M, JDN 'MINI' AIR HOIST *Extremely compact at a minimum of weight *High flexibility for varying working places *Few components for easiest operation and maintenance *Ideal as an inexpensive alternative compared to hoists with other driving media *Suitable for lube free operation, no additional oiler required *Suitable for application in hazardous areas *suitable for horizontal pulling *Newly developed braking system with little wear."
Weight: 26.0 Kg
Winch example (2)
Found: http://www.portablewinch.com/en/02.asp
- Portable
- There is no fixed link to a vehicle; therefore you can take the winch anywhere. Tether it to any solid object: a tree, a post, a rock or even to the ball hitch of your vehicle.
- Powerful - Up to 2000 kg (4400 lb) of pulling power
- The Portable WinchTM will pull 1000 kg (2200 lb) single line. If you need to pull extremely heavy loads, we offer a snatch block kit including a swing-side pulley and locking steel carabiner. The pulley is attached to the load with the carabiner, and the rope is attached to the winch anchor. This lightweight system effectively doubles the pulling power of the winch to an amazing 2000 kg (4400 lb) pulling capacity!
- Lightweight - Weighs only 16 kg (35 lb)
Both winches have differing merits, the second example is most likely to be the one our group will use during our calculations as it is portable, and could be carried by hand, it will not add significantly to our overall payload, and could be modified to enable it to take a greater weight.
Alternative websites also viewed:
http://www.northerntooluk.com/winches-and-hoists/electric-hoists/?sortby=priceascending&cm_ven=Performics&cm_cat=PPC&cm_pla=Google&cm_ite=electric%20chain%20hoist
http://www.winchsolutions.co.uk/
http://www.nextag.com/Master-Lock-Co-2953AT-506261517/prices-html?nxtg=26900a1c0512-35D7477F7F5880CA
http://www.nextag.com/portable-winch/compare-html
Minutes: 22/03/10
Tasks followed up:
Materials, winches and bearings suitable for the task were suggested (posted to blog and details also brought to meeting) along with their tolerances and specifications.
Calculations for the design chosen last meeting were attempted and it was established by most group members at the weekend that this design, although probably effective, was too complicated for us to successfully analyse.
As a consequence Designs (1), (2), and (3) were proliferated and given a basic analysis. Designs (2) and (3) were chosen by the group in the meeting.
Tasks for next meeting:
Finalise calculations for designs (2) and (3) to enable a choice of options for final proposal - for thursday.
Think of options for linking parts together - Pinning, slot parts?
Begin materials costings. (Aluminium for legs, steel for boom? - more durable? weight reduction?) (nb. Land-rover payload max 1500kg, tow 3000kg.)
Find weight of electric winches and post examples.
Future meetings:
Thur 25/03
Attendees of todays meeting:
A. Compton
J. Collins
A. Daniels
R. Dhillon
A. Dhillon
Materials, winches and bearings suitable for the task were suggested (posted to blog and details also brought to meeting) along with their tolerances and specifications.
Calculations for the design chosen last meeting were attempted and it was established by most group members at the weekend that this design, although probably effective, was too complicated for us to successfully analyse.
As a consequence Designs (1), (2), and (3) were proliferated and given a basic analysis. Designs (2) and (3) were chosen by the group in the meeting.
Tasks for next meeting:
Finalise calculations for designs (2) and (3) to enable a choice of options for final proposal - for thursday.
Think of options for linking parts together - Pinning, slot parts?
Begin materials costings. (Aluminium for legs, steel for boom? - more durable? weight reduction?) (nb. Land-rover payload max 1500kg, tow 3000kg.)
Find weight of electric winches and post examples.
Future meetings:
Thur 25/03
Attendees of todays meeting:
A. Compton
J. Collins
A. Daniels
R. Dhillon
A. Dhillon
Sunday 21 March 2010
Types of Bearing
When considering bearings, the main factor to consider is the type of load required for the bearing to withstand, the two main types are radial and thrust.
For use in the turning mechanism of the crane, a large thrust load and very small radial load will be applied to the bearing.
Plain Bearing
This is the most simple type of bearing, which simply consists of two surfaces that move past each other with no other mechanism. Often one or both of the surfaces is coated in a non-stick layer as well as being lubricated to further reduce the friction. This type of bearing has a very high load carrying capacity but also creates a lot of friction. They have a fairly high radial and relatively low thrust capacity.
Ball Bearing
Ball bearings have both a high radial and thrust capacity, and are found in a large range of applications where the load is small. Any load applied is focused onto a very small area, which makes it run smoothly and quietly, however this creates high internal pressures which may deform the balls should the bearing be overloaded.
Roller Bearing
Roller bearings are similar to ball bearings in the way they are made, having the key difference that they contain cylindrical rollers instead of balls. The rollers distribute the internal forces over a larger area, which reduces the internal pressure, making the components less likely to deform and vastly increasing the radial load capacity. Although the radial load performance is increased, this type of bearing has a very low thrust load capacity comparatively.
Magnetic Bearing
Magnetic bearings are ideal for high speed applications as they support the load using magnetic levitation which has zero friction and requires no maintenance. These bearings require a constant power supply as well as a sensor circuit to keep the inner and outer rings at a constant distance. This means that often a set of backup bearings is required in the event that a power loss to the device occurs. They have a relatively low radial load and extremely low thrust load capacity, and are most suited to continuous low load applications such as power generation or machine tooling.
Ball/Roller Thrust Bearing
This type of bearing is similar to ball and roller bearings in the way which they work, however the layout of the components allows a far greater thrust load capacity. This type of bearing is well suited to high thrust load applications, where radial load requirements are low. Rollers have the benefit of increased total load capacity, while ball bearings are smoother and run a lot more quietly as a result of decreased friction.
For use in the turning mechanism of the crane, a large thrust load and very small radial load will be applied to the bearing.
Plain Bearing
This is the most simple type of bearing, which simply consists of two surfaces that move past each other with no other mechanism. Often one or both of the surfaces is coated in a non-stick layer as well as being lubricated to further reduce the friction. This type of bearing has a very high load carrying capacity but also creates a lot of friction. They have a fairly high radial and relatively low thrust capacity.
Ball Bearing
Ball bearings have both a high radial and thrust capacity, and are found in a large range of applications where the load is small. Any load applied is focused onto a very small area, which makes it run smoothly and quietly, however this creates high internal pressures which may deform the balls should the bearing be overloaded.
Roller Bearing
Roller bearings are similar to ball bearings in the way they are made, having the key difference that they contain cylindrical rollers instead of balls. The rollers distribute the internal forces over a larger area, which reduces the internal pressure, making the components less likely to deform and vastly increasing the radial load capacity. Although the radial load performance is increased, this type of bearing has a very low thrust load capacity comparatively.
Magnetic Bearing
Magnetic bearings are ideal for high speed applications as they support the load using magnetic levitation which has zero friction and requires no maintenance. These bearings require a constant power supply as well as a sensor circuit to keep the inner and outer rings at a constant distance. This means that often a set of backup bearings is required in the event that a power loss to the device occurs. They have a relatively low radial load and extremely low thrust load capacity, and are most suited to continuous low load applications such as power generation or machine tooling.
Ball/Roller Thrust Bearing
This type of bearing is similar to ball and roller bearings in the way which they work, however the layout of the components allows a far greater thrust load capacity. This type of bearing is well suited to high thrust load applications, where radial load requirements are low. Rollers have the benefit of increased total load capacity, while ball bearings are smoother and run a lot more quietly as a result of decreased friction.
Original Design (from meeting 18/03/10)
Initial Design
After discussing each of our initial designs as a group, we came to the conclusion that the best type of crane to meet the specification would be a luffing crane with a counterbalance. A basic schematic of the layout was drawn in order to give a sense of the proportions and scale of the design.
With a 2.6 metre boom at 40 degrees to the horizontal, the total reach of the crane would be 2 metres about the centre of its rotational axis. This allows for an object to be lifted and moved a total of 4 metres from its initial point of pick up. Using a large base, and keeping the main body of the crane fairly low to the ground will lower its centre of gravity and increase stability.
Developed Initial Design #1
The initial design was then developed to include a cable spanning from the counterbalance to the tip of the boom, as well as a support up from the main body. The rotational axis of the crane was moved back slightly on the base to increase stability, thus reducing the required weight of the counterbalance.
It was also decided that a the crane could be rotated via a handle situated on the counterbalance, and also that a hand powered crank would be situated here to operate the winch.
After discussing each of our initial designs as a group, we came to the conclusion that the best type of crane to meet the specification would be a luffing crane with a counterbalance. A basic schematic of the layout was drawn in order to give a sense of the proportions and scale of the design.
With a 2.6 metre boom at 40 degrees to the horizontal, the total reach of the crane would be 2 metres about the centre of its rotational axis. This allows for an object to be lifted and moved a total of 4 metres from its initial point of pick up. Using a large base, and keeping the main body of the crane fairly low to the ground will lower its centre of gravity and increase stability.
Developed Initial Design #1
The initial design was then developed to include a cable spanning from the counterbalance to the tip of the boom, as well as a support up from the main body. The rotational axis of the crane was moved back slightly on the base to increase stability, thus reducing the required weight of the counterbalance.
It was also decided that a the crane could be rotated via a handle situated on the counterbalance, and also that a hand powered crank would be situated here to operate the winch.
Legs Of The Crane
After doing some research , I concluded that alluminium alloy would best suit the legs of the crane. There are two types, wrought and cast. Cast alluminium alloys are stronger but there are many types. On overage the properties are given below:
Yield strength = 250-450 Mpa
Density = 2600- 2790 kg/m3
Youngs Modulas = 70 - 74 Gpa
Tensile Strength = 300- 550 Mpa
Disadvantages of Alluminium Alloys
Alluminium has a lower tensile strength than steel hence the diameter of the pipe have to be greater in dimension than that of a steel pipe to deal with the same amount of stress.
Alluminium costs more than steel .
Adavantages of Alluminium Alloys
Has a high strength to weight ratio making the crane easier to carry .
It is immune to corrosion unlike iron or even steel to certain extents.
Yield strength = 250-450 Mpa
Density = 2600- 2790 kg/m3
Youngs Modulas = 70 - 74 Gpa
Tensile Strength = 300- 550 Mpa
Disadvantages of Alluminium Alloys
Alluminium has a lower tensile strength than steel hence the diameter of the pipe have to be greater in dimension than that of a steel pipe to deal with the same amount of stress.
Alluminium costs more than steel .
Adavantages of Alluminium Alloys
Has a high strength to weight ratio making the crane easier to carry .
It is immune to corrosion unlike iron or even steel to certain extents.
21/03 - Design 3
Design 3 ( The British Bulldog )
This design is a mixture of design 1 and 2 . It is interesting as it is something totally different to what is out in the market. It consists of a boom with supersonic legs and has the load sliding down the boom . The reason why we called it the british bulldog is because the front 2 legs are higher than the back two and the overall design looks like the shape of a dog. This also has marketability.
Advantages
As the struts or legs give more balance to the boom there may not be such a need for a counterweight.
The crane has a sliding system which is quite simple as there is no need for bearings.
The legs can be adjusted causing the boom to change in angle which can reach loads which are higher up with greater ease .
It can be de-constructed within seconds. The legs can be detached and the boom can retract into 2 causing very little space to be used up within the 4 x 4 rover .
bending moment and stress calculations would not be too complex .
Disadvantages
As the load is sliding down the boom, it may hit the ground before the intended point. It is important that the load is kept close to the crane or enough clearence is givin at the bottom.
There is no rotation which can lead to a bit of restriction.
This design is a mixture of design 1 and 2 . It is interesting as it is something totally different to what is out in the market. It consists of a boom with supersonic legs and has the load sliding down the boom . The reason why we called it the british bulldog is because the front 2 legs are higher than the back two and the overall design looks like the shape of a dog. This also has marketability.
Advantages
As the struts or legs give more balance to the boom there may not be such a need for a counterweight.
The crane has a sliding system which is quite simple as there is no need for bearings.
The legs can be adjusted causing the boom to change in angle which can reach loads which are higher up with greater ease .
It can be de-constructed within seconds. The legs can be detached and the boom can retract into 2 causing very little space to be used up within the 4 x 4 rover .
bending moment and stress calculations would not be too complex .
Disadvantages
As the load is sliding down the boom, it may hit the ground before the intended point. It is important that the load is kept close to the crane or enough clearence is givin at the bottom.
There is no rotation which can lead to a bit of restriction.
21/03 - Design 2
Design 2
This design has a different approach all together to design 1 and some may consider it to be more 'simple' . It consists of 4 main legs which will be adjustable with 2 rollers on the upper struts which will roll backwards and forwards in the x direction. There will be 2 winches, one to move the rollers in the x direction and one to move the pulley ( load ) in the y -direction. Andy is working on a sliding system for this design.
Advantages
The bending moments and stress analysis is simple to work out.
The legs are adjustable allowing them to reach places which are not each to get to .
There are no bearings involved which means there is less chance of failure within the crane .
No counterweights are needed for steadyness as the crane will be steady.
Disadvantages
Motion is limited. The load can only be transorted in a linear direction rather than at an angle as there are not bearings for rotation.
The cable can get caught with the winch.
As some legs would be shorter than others in certain situations, there can be a danger of tipping or the load sliding down at a faster speed.
This design has a different approach all together to design 1 and some may consider it to be more 'simple' . It consists of 4 main legs which will be adjustable with 2 rollers on the upper struts which will roll backwards and forwards in the x direction. There will be 2 winches, one to move the rollers in the x direction and one to move the pulley ( load ) in the y -direction. Andy is working on a sliding system for this design.
Advantages
The bending moments and stress analysis is simple to work out.
The legs are adjustable allowing them to reach places which are not each to get to .
There are no bearings involved which means there is less chance of failure within the crane .
No counterweights are needed for steadyness as the crane will be steady.
Disadvantages
Motion is limited. The load can only be transorted in a linear direction rather than at an angle as there are not bearings for rotation.
The cable can get caught with the winch.
As some legs would be shorter than others in certain situations, there can be a danger of tipping or the load sliding down at a faster speed.
21/03 - Design 1 (simplified from original)
Design 1
This is a simplified version of the original design. The design consists of a hand winch placed above the trunk and has a counterweight to allow steadyness within the crane.
The advantages and disadvantages of this design are stated below.
Advantages
Bearings will allow the crane to rotate , therefore there is greater accessibility for different angles.
The base is steady with four adjustable ( anglular adjustment ) legs.
The base does not take up much space and can access areas which are difficult.
Disadvantages
The bending moments and stress analysis will more complex .
The crane would suffer from the possibility of tipping over.
Bearings make the system more complex.
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