|Wheels in the "down" position|
A block is hinged to the leg. This block locks the wheels in the down position so that the bench can be wheeled around the workshop.
To move the bench you simply lift it at the side and the wheels drop down to the floor, the side blocks swing towards the leg and then the wheel rail comes up under the block and they lock in the down position.
To set the bench down on the floor you simply pull on the rope and that pulse the blocks inwards, allowing the wheels to flip up and the legs to sit on the floor.
I didn't follow Norm's plan exactly (mainly because I didn't remember all the details), so my version is maybe not quite as robust and I may decide later to revisit it and improve it. For now it seems to work okay.