Question about the overrun lever on a knott coupling

[yewtree]

I've just bought a knott KF13-C braked coupling for my trailer to replace a bradley.

The overun lever (sometimes called transmission lever) that connects to the brake rod has a large metal extension that faces downwards. See part 24 below and arrowed part on larger picture of the lever.

Nothing is attached to that extension, the handbrake and breakaway components being separate. (parts 22, 23 etc)

Can anyone tell me why that extension is there and what its function is?

All I can see at the moment is that in the event of the trailer becoming detached, that extension is going to dig into the tarmac and likely somersault the trailer before the brakes come on.


Second question, can anyone point me to a good description of how to fit a hitch lock and key to this coupling? (the ones I've seen so far are very brief and don't really even show where the lock goes, just something about punching out the roll pin.)

 

[IanB1485]

The runaway cable would hold up the the front of the trailer as it tensioned in the milliseconds before it engaged the brakes and then snapped , only then would the nose of the trailer fall and the now stopped wheels will stop the trailer fairly quickly. If you have a jockey wheel fitted , that would hit the ground before that part hit the ground. Re the hitch lock , you need to have part number 3 , and the lock barrel fits at the side of the handle preventing it from lifting when locked. aA competent thief would just unscrew the hitch and fit his/her own hitch , a better lock is one which covers the whole hitch , unfortunately if you have Item 3 hitch then I've not seen one that will fit and even if you found one, the advent of battery powered angle grinders make short work of locks. At a storage facility near me they took three caravans in one visit , cutting off all the various locks on the gates and caravans. Fortunately ( for me) having a small two berth which is fairly old they didn't touch mine