Help requested improving side dump mulch applicator

**ibdennyak** · Jan 29, 2021, 06:00 AM

Look up the Surplus Center in Nebraska on the interwebs and download their catalog. In the hydraulics section they have the specs for torque, hp, gpm, and rpm to help des9ign your system. You will probably want a gerotor type motor....low rpm, high torque.

**jedidiahwiebe** · Jan 29, 2021, 04:25 PM

Thanks very much for your reply. The one thing I'm still wondering about is what would be about the right specs for the job? 5000 foot lbs torque? 50 thousand? What about the rpm? I'm thinking one or ten rpm... But if that even feasable? Do hydraulic motors even have enough torque at low rpm? Or is torque independent of rpm?

**ibdennyak** · Jan 30, 2021, 04:53 AM

Unfortunately, I would have to have the machine in front of me to give you numbers, but first we have to put things in perspective. I am going to guess that your spreader loaded weighs maybe 2000 lbs. it is ground drive, so it needs enough traction to drive the beaters and apron. Probably 75% of the power is used by the beaters. If your tractor develops 35 horsepower, the apron uses a small amount of that because it is also powering the beaters, pulling the spreader, and moving itself. If it were mine (ingenious use of an old spreader by the way), I would get about a 5 hp engine and a reduction gear of some kind and power it that way. That would give you a nice range of speed rather than being limited to one,,,,,,just throttle the engine up and down.

That would also help you design a hydraulic drive. A Predator 212 engine develops 6.5 hp at 3600 rpm and about 8 ft lb of torque at 2500 rpm. If you want to run your apron at 25 rpm, it would require 800 ft lb of torque with a 100 to 1 reduction gearbox.

I would suggest you have your lady count the revolutions' of you apron sprocket as you run the machine and start from there.

**jedidiahwiebe** · Feb 10, 2021, 10:39 PM

Ibdennyak Well... to be honest the small engine does sound like a pretty good idea. Probably would be a lot cheaper than installing rear remotes. on my tractor and then the hydraulic motor.

When you say that the small engine idea would give me a nice range of speed rather than being limited to one... is that to say that with hydraulic I would not have a nice range of speed? I do want a range of speed. And I want it easy to adjust from walking behind the tractor.

There are hydraulic motors with way more than 800 foot lbs of torque tho are there not?

**ibdennyak** · Feb 11, 2021, 02:44 AM

Yes, but at what rpm? A hydraulic motor with 800 ft/lb at 2000 rpm would probably be the size of a car engine. A hydraulic motor motor with 8 ft/lb at 2000 geared to 20 rpm will have the same 800 ft/lb but at 20 rpm.....closer to what you need, and you can hold the motor in your hand. Torque and rpm are inversely proportional. in your case the small one is what you want.

There are hydraulic motors with variable speed. They are called hydrostats. One source would be riding lawn mowers. If you can find about a 12 hp or so lawn tractor with an operational hydro, it and the differential would probably be about what you need. You would still need more reduction (sprocket and chain) but maybe only 3 ot 4 to one. The output torques goes up as the rpm goes down. The complication comes in that you need about 3000 rpm to drive it.

There are other ways to vary the rpm such as power dividers, but they become even more complicated to design. Another problem with hydraulics is heat. The motor and oil get pretty toasty under load.

You still need to find the output rpm of your apron you desire before you can design anything.

**jedidiahwiebe** · Feb 12, 2021, 10:37 AM

Okay, perfect. As soon as weather permits. Maybe even next week I shall fetch it from the shed in the back field and drive it around a bit and count the revolutions. And the feet per minute!

**jedidiahwiebe** · Feb 21, 2021, 10:38 PM

Alright I've done it. I have taken the side dumper out for a walk with my lady. I need the driveshaft on the apron chain to run at 2 rpm, but with some room for variability.

Also I totally get it. Here I thought I was reading 800-2900 foot lbs on the torque rating of these princess auto hydraulic motors but I was reading INCH LBS. Ooooooh kay. Gotcha. Lol

Now how do I figure out how much torque I'd need for this apron chain? The box on this spreader is about 3' wide and 10' long. And I can put about 3 yards of wood chips in it at a time. (REALLY high sides!) So that could be a weight of 1200-2400 lbs when full.

Thanks to anyone who can reply! Much appreciated.