Bike trailer hitch adapter for rear rack (FreeCAD)

prusaprinters

Adapter for trailers with that old–fashioned high towing bar and bikes (e. g. recumbents) that don't have a conventional seat post. — I designed this to fit on the rear rack of my HP Grasshopper recumbent bike.You can alter some dimensions in FreeCAD in the dim spreadsheet to make it fit on other racks. First values to start with are durchmesser_traeger_quer — diameter, see photo: PINKabstand_laengs — distance in direction of travel in between the tubes, photo: BLUEabstand_quer — distance sideways in between the tubes, photo: GREEN … changing other dimensions may result in the need to re–model some fillets and chamfers, etc.. PrintingPrinted in PETG, 0.4 mm nozzle, 0.25 mm layer height and with lots of perimeters and infill… see attached .3mf files (PrusaSclicer 2.6.0 beta 3 or better) for more details. Scale the big green nut (Verschlussmutter) 101 to 102 % on X and Y (not Z) so it can easily fit on the threaded rod. Do not scale the thread under the base plate, because you don't want the rod to come loose there. I printed most of the parts separately. AssemblyYou need some additional parts for assembly:standard trailer hitch (obviously 😉)50 mm M8 bolt [1 pcs ]M8 nut [1 pcs ]70 mm steel axle, 4 mm diameter [1 pcs ]40 mm M8 threaded rod [1 pcs ]some glueBy the FreeCAD design and the photos provided it should be pretty clear what goes where. The little round cover to hide the axle must be glued in. You need to glue on the rear cover (CoverKupplung) which adds some prevention to the coupling not to twist around the 50 mm M8 bolt. You may add some glue to the 40 mm rod inside the base plate and some to secure the nut on the 50 mm bolt.  Have fun, give it a like and please share your make with us, thanks! 👍