Financial Evaluation

once we had finalised the design we needed to do the stress analysis to determine exactly what the dimensions were for each component. after researching into the different types of metals and dimensions we were then able to find prices for the specific material. we obtained these prices from www.aluminiumwarehouse.co.uk

Metal Structure = £333.91
Roller System Mechanism = £46.98
Winch = £21.14
Beam Joint Supports =£100
Connection Pieces =£55.74

Total =£557.77

Chosen Roller System

The chosen roller system we have chosen is a heavy duty roller fairlead. we have chosen this product because it is more than capable of supporting the load. infact it can cope with 5440kgs. it has galvanised rollers for durability and to prevent corrosion. This product is shown below.


this product can be purchased from from a company called machine mart. the details are on http://www.machinemart.co.uk/

Joining Methods

There are a number of different joining methods which could be used in our design. This is a very important issue as the joints within a structure holding heavy weights will be put under great pressure. we must make sure that the method chosen is the most suiable.

Nuts and bolts

this is an acceptable form of connecting 2 or more parts together. they are very adaptable and can be purchased from a number of different distributors at a very cost effective price. each joint will be put under different amount of pressure. this means that the nuts and bolts used at each joint will vary when determining the properties. such as the type of metal used, the thickness/diameter and even the length. another factor to consider is weathering. as the crane is designed to be used outdoors, it will be exposed to the elements. this means that there is a posibilty that the nuts and bolt could corrode. This is why the material selection is very important.

Transportation Limitations

As th design brief states that the crane must be able to be disassembled and put either into the back of a land rover sized 4x4 or on top of the vehicle, this means we only have a limited amount of space available.



The maximum space available is:
Width - 1146mm
depth - 1950mm
height - 1027mm

This means that all of the components must be within these limits once bundled together

Materials Research 2

MATERIALS

Our crane must be strong and durable. In order for us to succeed in choosing the best material, we have to look into many different properties of different materials.

We have chosen to decide out of steel and aluminium for the material of our crane. Below you can see some advantages of each material

Aluminium:

Aluminium has the following properties:

Density, 2.7 Kg/m^3.
Yield strength, 55 MPa
Tensile strength, 125 MPa
Young's modulus, 69 GPa

This would be an ideal material to use for the crane. It is low in weight, does not corrode easily and can be melted easily

Steel:

Steel has the following properties:

Yield strength, 250 MPa
Density, 7.85 Kg/m^3
Young's modulus, beteen 190 and 210 GPa
Tensile strength, 280 MPa

Steel would also be an ideal property, however it is very costly compared to aluminium.

Chosen Lifting Mechanism

After considering all the different type of lifting mechansims which would be suitable, we have decided to go with a puller/winch as shown below.

Clarke CHP1250 Heavy Duty Power Puller

we have chosen this product for a number of reasons. it is readily available from a number of different distributors, so replacing the product in the event of a failure will not be too much hassle. This product contains a limited number of components which means there is less to go wrong. It only costs £21.14 inc. VAT. Also It can cope with weights up to 1250kg, which is more than enough.

this product can be found at http://www.machinemart.co.uk/shop/product/details/chp1250-heavy-duty-power-puller

Ideas for winching the load

I've been thinking of ways to lift the heavy load into the air so that it can be moved 4m. I've thought of a number of ways which i think would be suitbale. The first idea was a rachet puller. There a number of different variations of this type of product and i have shown a couple of them below.

Cable Rachet Puller -http://img.hisupplier.com/




Chain Rachet Puller - http://www.e-rackonline.com/











Both of these products are able to lift much more than 1 tonne. The cable ratchet puller is obviously lighter as the chain rachet puller has heavy chains. This product would be connected to the top of the crane.


Another system i have thought of is the block and tackle pulley system. It works by having two pulleys connected with a rope. it works by the pulleys either coming together to lift the load or move apart to lower the load. When you pull the rope with little effort it is magnetised and makes ease of lifting the heavy load. The effort seems like alot more than it acually is.


Block and Tackle pulley system - http://www.factmonster.com/