This may be a hot topic...
I am looking at possibly putting a hydraulic drive motor on a Bercomac snowblower which turns at 3600 rpm to cure the belt drive fiasco. I am looking at a 0.50 cubic 1,992RPM 141 inch lbs 4.5 GPM.
By the math I would need a 10.5 inch to 11 inch pulley on the drive motor but I guess what I am asking is there enough torque int he drive motor to do the job...
Fire away guys..
I don't recall which tractor you have nor do I know what pump is in it or how worn that pump is but for the purposes of discussion, I will tell you this.
Let's assume that your pump is still capable of delivering a solid 8 gallons of oil per minute when the engine is spinning at 3600 RPM.
8 gpm X 231 = 1848 cubic inches
If you had a hydraulic motor that was 1 cubic inch in displacement, then it would spin at 1848 RPM. If you use a motor with .50 cu in displacement the RPM doubles to 3696 rpm or ....pretty much the speed you desire. No belt or pulley would be needed. Instead, you would use a LoveJoy coupler to connect the motor shaft directly to the input shaft of the gearbox on the blower. You need to use a geroller or gerotor or orbit style motor. Three names-same item.
I have no idea how much HP is needed to run a 2 stage Berco. If I were you, I'd be on the phone to their engineering department and talking with them about your idea. They produce hydraulic drive blowers. Therefore, they will have already done all the calculations and can tell you more than any of us can. As already pointed out, there are limitations regarding the maximum amount of HP the standard hydraulic system in these tractors can produce.
Three things are at play. Oil volume, operating pressure and engine HP. If you attempt to increase either volume or pressure, then more HP is needed. If you increase the volume beyond a certain point, then the size of the hydraulic lines, cooler, control valve etc get exceeded and excess heat is created. If you increase the HP from 16 to 32, the OEM hydraulic system really does not care because volume and pressure will dictate how much HP is delivered to the drive motor, not the engine HP.
As tempting as hydraulic drive may be, I personally believe that sticking with a drive belt will give you the best results. In order to convert a Case snowblower that was designed for a 3 digit tractor to work on a 4 digit Ingersoll, the counter-shaft that the driven pulley is mounted to has to be replaced with one that is a bit longer. I think that you may find that this needs to be done with the Berco but I don't believe that it is impossible to solve this rotation issue.