I came across this retractable sliding cargo logistic box design that I want to use in a warehouse concept, but i am having difficulty designing that mechanism. Basically, the logistic box has 4 legs each leg have an independent caster wheel, but with a push of a button the front legs fold and the whole box gets slide onto a vehicle(in my case warehouse shelve). Please help me to find any existing design mechanism from which I can get the idea or any concept you think will work. Also, plz provide some knowledge about the sliding mechanism that can be used(considering moderate use) I was also thinking of designing the rail/guide tapered at starting. so the box can easily be slide in and be above the ground.