Tow ball

[Alan]

OK so I need a towbar on the back of my 463 and I have been given an old one that will fit. My question is:
What is the limit of wear on the ball?
i.e. it should be 50mm in diameter but what is the smallest it may be before I start loosing the trailer?
I've heard of someone loosing his trailer while driving and it was eventually ascribed to the ball being too small.

[karoogw]

Hallo Alan.
With a lot of pulling trailers on the farm and on gravel roads the dust and mud is an issue for wear on the tow ball aswell on the coupling.
I find if the coupling is new i can still pull a trailer with a ball wear of 2mm but if i pull a trailer with a worn coupling then it become an issue of loosing the trailer.
I find the most wear on the pulling side of the ball ( the side closes to the bolts ) and the same on the coupling.
After a few nasty insidents i've change all the towball's to heavy duty pinnball tipe and the trailer couplings on the heavy trailers to eye and ring couplings.
Now if i detect any wear i only replace the ring on the trailer coupling and the pinball

[Andrew]

What about lube - like graphite?

[karoogw]

Ja, that will work if you travel just on tar and after every trip you degrease it, but a detnate no no on gravel roads, the grease and dust become grinding paste and will work the tow coupling and ball away.
If you do detect iron scarfings or iron chips on the ball, it's a indication that the trailer is to heavy for the towball. BE AWARE!

[Alan]

Thanks for the replies,
I have measured the ball to be 49mm ie 1mm undersize.
You would think that is still ok then?
Its a pity the ball cannot be replaced on its own.

[Pete460332]

There is both a 50mm and a 50.8 mm tow ball standard - see http://en.wikipedia.org/wiki/Tow_hitch

Wear limit is 49.61 mm for the 50mm ball :
ref: on page 164
http://www.swiftgroup.co.uk/uploads/...aintenance.pdf

also here ( decimal poin tis missing should read 0.39 mm not 39 mm )
http://www.nationalcaravan.co.uk/ima...final_rev1.pdf
Peter