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.

[doodlebug]

The best that I can offer,is a copy of the original Kyosho manual. There were a couple of other member's that have experience with this model. I think Customrcmodler was one of them, I hope he chime's in.
Later, Neil#2 aka doodlebug.

[Vanisle]

You would think that the manual would have come with the brand "new" one I bought ... but no. I would appreciate if you could send me a copy. I will pm you with my email address. Thanks.

Richard

[Espeefan]

I can't offer much advice on the screw drives, but I can offer some advice on the gearmotors you want to use for the drive wheels.

I think you'll find 150 RPM gearmotors to fast for the loader. With a 5" diameter tire, the loader will be covering a little better then 15" of ground, per one revoltion of the tire. Multiply that by 150 RPM (full throttle on 12 volts), and your loader is going to be covering 2,250" per minute, or 187.5 feet. That's pretty fast. About 2.13 actual miles per hour. Or looked at another way, at full throttle, it will cover 37.5" per second. That seems a little on the high side.

On a 7.2 volt pack, the same gearmotor should do about 90 RPM.
1,350" per minute, roughly 1.2 mph. Or 22.5" per second. Better, but still a little on the high side, at least in my opinion.

If it was my project, I'd suggest going for a something around the 30 to 50 RPM gearmotor range, on 12 volts.

[steamer]

It's pretty ease to figure out screw drive RPM. Just measure one inch of the thread and count the number of threads in that inch. That way your know how many turns of the the screw it takes to move one inch. If the screw has 32 tpi. and the gear drive is 32 it's going to take one minute to move that 1 inch. If you want to know yours count the threads on your screw, time how long it take to travel the inch and you'll know the RPM
Say the thread pitch is 20 and it takes 15 sec. to move the inch.
Take 1 min.= 60 sec Div. by 15sec.=4x20tpi =80RPM
So it's going to take 80RPM to move the 20tpi.screw 1in. in 15 sec.
Rob

[Vanisle]

Originally Posted by Espeefan

I can't offer much advice on the screw drives, but I can offer some advice on the gearmotors you want to use for the drive wheels.

I think you'll find 150 RPM gearmotors to fast for the loader. With a 5" diameter tire, the loader will be covering a little better then 15" of ground, per one revoltion of the tire. Multiply that by 150 RPM (full throttle on 12 volts), and your loader is going to be covering 2,250" per minute, or 187.5 feet. That's pretty fast. About 2.13 actual miles per hour. Or looked at another way, at full throttle, it will cover 37.5" per second. That seems a little on the high side.

On a 7.2 volt pack, the same gearmotor should do about 90 RPM.
1,350" per minute, roughly 1.2 mph. Or 22.5" per second. Better, but still a little on the high side, at least in my opinion.

If it was my project, I'd suggest going for a something around the 30 to 50 RPM gearmotor range, on 12 volts.

Thanks for the info. I was able to use my tach to measure the current wheel speed, it was approx 21 RPM for the 5 inch tire ... at least for the 10 seconds or so until the gearbox started slipping and the wheels would no longer turn. "Ready to run" - not. So that would be approx 300 inches per minute, .267 MPH or 5 inches per second. No wonder it seemed slow.

Richard

[Vanisle]

Originally Posted by steamer

It's pretty ease to figure out screw drive RPM. Just measure one inch of the thread and count the number of threads in that inch. That way your know how many turns of the the screw it takes to move one inch. If the screw has 32 tpi. and the gear drive is 32 it's going to take one minute to move that 1 inch. If you want to know yours count the threads on your screw, time how long it take to travel the inch and you'll know the RPM
Say the thread pitch is 20 and it takes 15 sec. to move the inch.
Take 1 min.= 60 sec Div. by 15sec.=4x20tpi =80RPM
So it's going to take 80RPM to move the 20tpi.screw 1in. in 15 sec.
Rob

Thanks for the info.

Well, only one of the 3 screw drives actually still works, sort of (the other two just slip the gears on the shaft) and I was able to measure it like you suggested. It was 32TPI and it took 4 seconds to move one inch so that is ((60/4) x 32) = 480 rpm. The screws drives are definitely not slow. Looks like I was way out on even considering one of the gear motors I have lying around. I was just going to use the existing screwdrives but all 3 no longer work ... and I haven't even used it yet other than to drive 5 feet on the garage floor. It's a project piece for sure.

[kartman01]

Were you able to swap out the mechanical parts for hydraulic? If so, could you post some photos?