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All,

I know nothing about hydraulics, except maybe how a wood splitter works, and know there must be some simple calculations or practices regards pumps and motors. At least with my quandary.

The question;

If I have a 18 horsepower engine with an operating speed of 3600 rpm, and with a driveshaft, it drives a rototiller with an input speed of 3600 rpm's, 1-1, one to one, and now, I remove the driveshaft and put a pump on the engine and a hyd motor on the tiller, what do I need for hyd motor and for a hyd pump?

Bonus question; If I drive two tillers at the specified 3600 rpm's, would I need two pumps (stacked) to drive the two motors?

Any help would be greatly appreciated. I was a Combat Engineer (12B) for 27+ years and dig a pretty good battle position, but I am getting nowhere with this.. My searches have been futile and or have lead me down a rat hole...

Thanks,

Carl
 

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All,

I know nothing about hydraulics, except maybe how a wood splitter works, and know there must be some simple calculations or practices regards pumps and motors. At least with my quandary.

The question;

If I have a 18 horsepower engine with an operating speed of 3600 rpm, and with a driveshaft, it drives a rototiller with an input speed of 3600 rpm's, 1-1, one to one, and now, I remove the driveshaft and put a pump on the engine and a hyd motor on the tiller, what do I need for hyd motor and for a hyd pump?

Bonus question; If I drive two tillers at the specified 3600 rpm's, would I need two pumps (stacked) to drive the two motors?

Any help would be greatly appreciated. I was a Combat Engineer (12B) for 27+ years and dig a pretty good battle position, but I am getting nowhere with this.. My searches have been futile and or have lead me down a rat hole...

Thanks,

Carl
Here are some links;
Horsepower Calculator - Metaris Hydraulics

More;
https://www.arboristsite.com/community/threads/hydraulic-engine-pump-sizing.307578/

More;
https://www.google.com/search?source=hp&ei=PeJ4XPbfMtPY-gTbkI_QDw&q=hydraulic+motor+formula+horsepower&oq=hydraulic+motor+calculator&gs_l=psy-ab.1.6.0l2j0i22i30l8.1630.12464..18887...1.0..0.770.19748.5-11j17......0....1..gws-wiz.....0..35i39j0i67j0i131i20i263j0i131i67j0i131j0i20i263.aYM7Fs_GBXc

I don't think the Tiller turns at 3600 RPMs that is really cooking for a tiller? Sure there isn't a chain or gear reduction some where between the engine and the tillers?
 

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The Surplus Center has a bunch of different calculators; Surplus Center

Look in the left column for different ones.
 

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Carl, Your bonus question is easy, "No." You'll need 1 pump with an output of slightly more than the input required for both hydraulic motors. From the rough/estimated info I found for a JD Model 30 tiller, you'll need a hydraulic motor requiring .65 cubic inches per rev. Two motors would require a pump of 1.3 cubic inches per rev...I'd use 1.5 minimum.

As a side note, make sure your pump is going in the correct rotation, or get a reversible pump. Your also going to need a reservoir and a relief valve, plus hoses & fittings!

Hope this helps...more than it confuses! Bob
 

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The Surplus Center has a bunch of different calculators; Surplus Center

Look in the left column for different ones.
Beat me to it. I have used this before and found it very helpful and pretty accurate for my needs. :thumbup1gif:
 

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Discussion Starter #6 (Edited)
I acquired two brand new 33" tillers (Bolen 18322), which from all the research I have done, either require 3600 or 2750 rpm impute. They are belt driven either engine speed or reduced a little. I know that's fast, but that is what it is. I plan to bolt together and drive with hydraulic motors, etc., for a 66" tiller.

My tractor for this project is a Case 446 with a Wisconsin TJD repower. The tractor is hydrostatic and has its own little pump. Once I mount the motor, it's my chance to upgrade the pump(s) etc.

I really don't want to go the belts, chains and jackshaft route.

Also, some 446's came with aux hydraulics, but I am not sure if they shared the hydrostatic pump or had a different setup, however, the Case tillers turn slow and are not that great, IMO.

Anyway, I have looked at some of the resources listed and I have a hard time with the numbers etc. But will work through it.

Thanks,

Carl
 

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Carl, Take a closer look at your tiller(s) 3600-2750 can very well be the input speed required, but you can mount your pump directly to the tine shaft. I haven't gone through the math, but I'm thinking 500 rpm on the tines is max!

Typically, all tillers use engine rpm as an input rpm. The pulley at 3600 rpm drives a larger pulley...reducing the rpm.... This then drives a 90 degree gearbox...which may or may not be a 1 to 1 ratio... and the gear box drives a sprocket driving a second larger sprocket eventually ending "around" 200-500 rpm of the tiller splines.

Keep searching for info on other hyd. tillers and determine the flow required at/for the motor. It will be a difficult project, but one that will work. Bob
 
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