Big Bobby Car (BIG-BOBBY-CAR) towing adapter for broom stick with quick release and universal broom hook

thingiverse

### History Everyone knows that pushing a child in a bobby car is a back-aching task until the kid can move it on their own. To help with this, you'll need something to push or pull your bobby car into an upright position. Typically, you'd go for the original push bar provided by Big…. unless you have a special edition like a Porsche, Mercedes, or older Audi, VW, or BMW model, which is what I have. For most of these special editions, the original push bar won't fit. I found a design on Thingiverse called *Klein-laui* and tested it… It was fun and worked… for about 5 minutes until the broom adapter snapped clear off the clip…. So I took the quick release concept and added some stiffness to the design. What you get now is the 5th iteration of the design (the kids in my street running five bobby cars are a very good test group). The design can withstand most stress, but doing the math on what torque you can apply with an average 1.5m long broomstick on a 50mm wide plastic part clearly shows some limitations. But I am confident that for the time until your kids can ride the bobby car on their own, this design will help prevent back pain and give them lots of fun. ### Design The design consists of two sections: one for the broom stick and one for the steering wheel. - The section for the broom stick includes a left part (also available in a little bit bigger size), a right part, and a release part. - The section for the steering wheel includes a clippart, a wheelpart (for classic or modern wheels), and a universal hook (add-on, not required for the initial design). ### Additional Parts For assembly, you'll also need these additional parts: - 1x M5x50 screw with cylinder head - 1x M5 nut (self-locking if possible) - 2x M4x45 screw with cylinder head - 1x M4x50 screw with cylinder head - 3x M4 nut - 1x M10x50-55 screw - 1x M10 nut self-locking - 1x spring DIN2095 5.7mm diameter 35m length (you'll need to cut the spring in half; you might also be able to use the 25mm version, but this hasn't been tested) - Alternative for the spring: 2 ballpoint pens with springs inside (these should work even if you can't get a hold of DIN springs) ### Assembly Instructions #### Wheel Section: Just bolt the wheel part to the clipart with the M10 screw and nut. Make sure to pay attention to the orientation if you're using the modern wheelpart; the classic one is symmetric. Remove the original screw from the wheel at the bobby car, fit the wheel section around the wheel, and use the M5x50 screw and the M5 nut to assemble everything again. #### Broom Stick Section: First, test the printing tolerances by assembling only the left, right, and release parts. Insert the clippart of the wheel section. You might need to grind or cut a little bit on the clippart to make it fit. Now repeat the process on the other side while inserting the release part into the opening. Take out the metal tool you used to compress the spring, and the spring should snap into place at the release part, holding it in position. Now apply the M4 screws to press the left and right parts towards each other. Insert the wheel section and test if the springs apply enough force to securely lock the release part. Now just screw a broom into the cone thread, and you're ready to go! ##### Disassembly: If you need to disassemble the broom part, you might need two thin metal parts to step by step push the spring into the hole at the side parts so you can pull out the release part. I used 2 watchmaker screwdrivers to get it done in 10 seconds. ### Universal Broom Hook: I included this design to be able to hook up the bobby car to a pedal car with a trailer hitch. You can also use this to hook up other stuff to a bobby car with a trailer hitch or even build a multi-bobby car train. ### Disclaimer **This design is not tested by any official organization regarding children's safety!** Using this design is at your own risk. Always apply common sense and never leave your children playing unattended! Always remove damaged parts immediately! Please let me know if you find any problems with the design or the description, I can rule out the problem and make the design safer