Westfalia Friction Towhitch

[Beano]

My (new to me) 1995 Knaus 'Sudwind' van has an early Westfalia friction towhitch with a hydraulic damper which presses steel pads against the towball via external 'arms'. It all seems to work well and the towball is meant to be kept 'dry' but when driving with the window open I can hear a disconcerting and constant graunching groaning sound from behind. Is this normal with this device (obviously not a common fitting in UK)

Roger

 

[Beano]

addendum - The hitch is a Westfalia SSK1, and has metal pads - is there possibly a later type which has fabric friction pads? I.e. like brake pads?

 

[Roger_374578093]

Me again - upon closer inspection the highly burnished-black pad ends ARE friction material - I've bought new pads at an extortionate