I have to create a crane to support a dead load for my Engineering Technology class. It can be made out of only 1/8 inch balsa wood and wood glue, and is going to be graded by the ration of weight held to structure weight.Could anybody give me some suggestions as to how to go about designing this thing? I already know most of the basics, but if anybody could give me some specific tips, they would be greatly appreciated.Thanks!
Not enough information because a crane can be many shapes and have various forms of anchoring or counterbalancing the load. If you are not allowed to anchor to a base and can't use weight to counter the load (if all balsa) then you have to create legs and lift the load between them - Basically the design will need to be triangles in truss to take the compression and prevent twisting and a long upper piece in tension to act like the cable you don't have. I would make two legs that are each 3 sided trusses that meet at the top and have a single rod across the bottom to keep them from spreading. Then I would make a longish beam with flat triangles for stiffness and use a few uprights to position the tension rod. Hang the weight on one end and push down on the other so it pivots on the short legs.
Is this for a nuclear power station? If 2500 Te and 60m really are the specified loads and span then it is likely that it will be used very seldom. In theory you can design for any load to be lifted but maintenance on a crane system that is used once a year (10 years?) is a real problem. The main items to consider are: Availability of winches and bogies which then dictates running beam and rail sizes. For the spanning beam several alternative sizes needed to be designed and then costed. It will be not just weight but transport costs that determine the most efficient sizes The overall height of the crane will then determine the required roof height assuming that the crane is under cover. For comparison the Harland and Wolf cranes in Belfast called Samson and Goliath can lift 840 Tonnes each. Overall design needs to consider speed of travel, acceleration and deceleration rates and a host of other things.
