Beskrivning
For the curious beginner
Here we have a tow ball that makes no apologies for itself. It is 50mm in diameter and attaches with a threaded stud: 3/4 inch in diameter with 16 threads per inch – a classic UNF mount. It is not something you slap on any trailer and then roll into the vehicle inspection with a smile – no, this ball is not approved by the SBP , and our Finnish neighbors say no thanks either. Suitable for mounting on Yarbo robotic lawnmowers.
But for those of you who build your own, test gadgets in a fenced area, or just like to screw things together that look sturdy – then you’ve come to the right place.
For the medium-tech enthusiast
The technical heart of this product is its threaded mounting stud: 3/4″ x 16 UNF , which stands for Unified National Fine thread. It is a tight thread that is widely used in American applications where vibration-proof mounting is important. The ball is 50 mm in diameter – the standard size for many couplings, but forget about using it for road traffic if you are in Sweden or Finland. Not type approved , which makes this a part suitable for test environments, prototypes or farm vehicles .
Material wise? Probably steel, often zinc-coated for some corrosion resistance, but this should be verified depending on the manufacturer. Tightening torque should be adjusted to the thread’s load-bearing capacity and the material in the counterpart.
For the complete tech geek
Ball diameter: 50 mm ± tolerance according to DIN ISO 1102 (if the manufacturer complies with this)
Thread specification: 3/4″-16 UNF-2A (external thread, fine thread pitch of 1.5875 mm)
Thread length: Often around 38–50 mm, but this varies.
Material: Typically C45 carbon steel or equivalent, often with an electrogalvanized surface
Use: Not E-approved (i.e. lacks type approval for trailer use on the road)
Suitability: Vehicle prototypes, agricultural machinery, off-road vehicles, hobby sleds
Not approved by: SBP (Swedish Motor Vehicle Inspection) and the corresponding Finnish authority – probably Trafi.
Note: No marking, no approval number, no E-stamp. You’re out in the wilderness here – but sometimes that’s exactly where you want to be.
