Hanomag Screwdrive and Wheel Speed

[Vanisle]

Screwdrive Speed

I recently bought a "new" built Graupner Hanomag 66C loader. Unfortunately, it arrived damaged (including a bent fender, bent exhaust and cracked rim) due to poor packaging, the electrics are a bit of a mess and the screwdrives for the bucket promptly broke (one because the end of the screw came out of its holder and the other where a retaining ring fell out and the screw slips off the gear). It pretty much needs a complete rebuild including better electrics and a lot of reinforcement because it is so light duty.

I have question about the screwdrives (which use ESC's). Does anybody have any idea what the max RPM for the screwdrives should be? They are a pretty fine thread and approx 1/8 inch diameter. I have a optical tachometer but no way to attach reflective tape to measure the RPM. It looks like they are 380 sized motors and are 7.2v.

Here is a photo of one of the screwdrives:




I am contemplating changing the screwdrive motors to 12v gear motors. Any idea what RPM would be a good speed - 17, 34, 120 or 200?

Also, is there any way to limit the end travel of the screwdrive? Although I realize that you can simply find the "feel" for the end limit, I want my kids to be able to use it without having to worry about this. I guess I could just convert it to hydraulics and maybe that is what I will do eventually but that will involve a lot of work.

Wheel Speed

The loader is only 2 wheel drive and really slow, too slow for any real use. Fortunately, there is plenty of room to make it 4 wheel drive with 4 gear motors. I have some 120 rpm gear motors and will be using the RC4WD Mil-Spec tires that are 130 mm diameter (5.1 inches).

I am not very good at figuring out the wheel speeds based on RPM's, etc. Will 120 rpm's be way too fast using 12v and a Sabertooth 10A ESC? I could slow it down by using a 7.2, 8.4 or 9.6v battery. I will use a separate battery for the wheel motors and the screwdrive motors.

I'd apreciate any help you can offer.