What is the point of this?
It is a handbrake on a farm trailer. Yes, I suppose it has to be fitted by Euro law or some health and safety rule.
You know what will happen. If you actually use it on a slope the trailer will roll away anyway. If you come back in a week it will have rusted on and the wheels will be locked.
They fit them. No-one uses them.
At least it is somewhere to hang the hydraulic pipe...