Thank you for the comments so far.
Jamie: I think you have the idea. First thing that will happen when using the ram is the top claw will come down. When that hits an oponent it will crush the weight then finally lift the lower part of the arm.
The larger the object the higher it will lift, the smaller the object the less it will lift.
It has a bite of around 250 and might put a min bight of 100 - 80. This is to help the shrimec.
It should bite quickly as the claw doesnt have to move much to bite then lift.

Calum- Thanks for telling me your experiences of a boxsecion bracket. I thought alignment would also be an issue. I was thinking about pillow block bearings but they are expensive and not light 4kg and 64quid. The wheels all ready have bearings as well. I do have a mill built into my lathe but I have no chance fitting that base plate onto the bed. I dont think it can handle milling hardox as well.

Thanks again guys
Marco