Disco Kid Posted December 29, 2014 Share Posted December 29, 2014 Thanks for the pdf Disco Kid, very interesting. Does anyone remeber the 1 1/4" dia. ball hitch? Yes I am realy that old LOL. On the Dixon-Bate, where the ball was on the van and the cup on the car . . yeah . . I think Raven caravans may have used it. Quote Roughing it . . but in comfort . . Link to comment Share on other sites More sharing options...
beejay Posted December 29, 2014 Share Posted December 29, 2014 Remember too that apart from the differing diameters, the 2" (50. 8mm) towball has a different profile from the 50mm item as there is no ledge below the 2" ball for a latching mechanism to locate in. 2 inch towball profile. jpg 50mm towball profile. jpg Is the "ledge" undercut on the 50mm ball intended a safety latch? Unfortunately, ISO 74056 is not available on line to check and rather expensive to buy. Whilst there must have been a reason for it 'standard' hitches use a shaped locking block that closes and is locked into place under the rear lower half of the ball and forces the ball into the front spherical section of the hitch cup forming a three-quarter spherical socket so that the hitch cannot become detached in normal use. Shows in fig 14 here http://tinyurl. com/p2yc7ov Interesting Al-Ko ball socket accessory available in Australia here http://tinyurl. com/otscttf Quote Link to comment Share on other sites More sharing options...
CommanderDave Posted December 29, 2014 Share Posted December 29, 2014 (edited) Isn't it a requirement of ISO 74058 that a 50mm tow ball has a flat top and 50mm stamped onto it? If I remember right thats correct . AUS and US use Imperial towballs . Might be worth looking at US vehicle parts suppliers here . Changing to a 50mm hitch would make it more recoverable if needed as not many recovery vehicle could tow it . Dave Edited December 29, 2014 by CommanderDave Quote Jeep Commander 3. 0 V6 CRD Isuzu D- Max Utah Auto Elddis Crusader Storm 2000 Kgs, Unipart Royal Atlas Mover . Link to comment Share on other sites More sharing options...
Black Grouse Posted December 29, 2014 Share Posted December 29, 2014 (edited) Australia uses 50mm towballs http://www. towingguide. com. au/content/couplings. html as it's a metric country. USA uses 1 7/8", 2" or 2 5/16" depending on application, it's not really an imperial country but a few units co-incide with UK Imperial measure. . Edited December 29, 2014 by Black Grouse Quote 2015 VW Touareg 3. 0 V6 TDI + 2013 Lunar Clubman ES Link to comment Share on other sites More sharing options...
Guest Posted December 29, 2014 Share Posted December 29, 2014 Is the "ledge" undercut on the 50mm ball intended a safety latch? Many older 2" hitches could rotate 360deg around an axis aligned with the direction of vehicle travel, but this is not the case with the 50mm designs as these have limited rotational movement, and so I believe the undercut is primarily to provide additional clearance for when on uneven surfaces, but please confirm this with the manufacturer. Gordon Quote Link to comment Share on other sites More sharing options...
Arc Systems Posted December 29, 2014 Share Posted December 29, 2014 I towed a 25cwt trailer with 2" hitch for years on a 50mm ball, that generally including towing over rough terrain on construction sites. I can then say with some certainty it don't come off, albeit if it was to do, you would probably notice the absence of the rattle but then again. ... I never greased it either! Quote Arc Systems are specialist Carver caravan product repairers, committed to providing a comprehensive service as well as spare parts for these popular heaters. Link to comment Share on other sites More sharing options...
The 2 Tops Posted January 17, 2015 Share Posted January 17, 2015 I'm happy to take that Alko link as definitive - but the figure of 49. 61mm just seems a strange number. I think the wear tolerance is derived from the older, imperial measurement times. The allowed wear (50 - 49. 61) gives a figure of 0. 39mm which equates as near as dammit to 0. 015" (fifteen thousands of an inch), which sounds right from an engineering point of view. Quote Link to comment Share on other sites More sharing options...
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