Builders Yard

On 26 June 2010 Paul Yearsley wrote:

Dear Ivor, I would like to make a working model of a grab crane. I would like the grab to be able to open and close at any point or height rather then some designs where you have to lower to the floor to open and close. I notice that your crane grab opens and closes at any point. How do I make this happen? Do you use two winch drums — one for holding, the other for open/close and then some sort of brake on the holding drum so as to activate the grab, or is there another simple way of doing this? Do you have a detailed plan of the winch mechanism that I may be able to purchase? Many thanks, Paul.