Motor question

[woodlandfarms]

I am looking at a motor on Suprlus Center --- It says 2000PSI cont, and 2500 momentary.

My tractor is 3000PSI rated.

Am I going to ruin it? The motor, not the tractor although I guess I should ask about both.

 

[J_J]

You simply put a relief valve across the motor, set at 2000 psi..

You do know the motor will only develop max psi when worked hard.

Just doing light work, you may only develop 1500 psi.

If you had a gage in that hyd circuit, you could see the pressure at any time.

 

[woodlandfarms]

It is for the stump grinder project. I keep waffling on motor sizes. 800RPM is what other Hydrualics run at so that is between 3.6 and 4.4 CU. I think as the motor will be lovejoyed to the wheel it is going to take a bit of a beating.

 

[J_J]

Why not do it like the engine driven stump grinders, belt and pulley.

 

[muddstopper]

I'm with JJ on this. Coupling the motor directly to the grinding wheel is going to place a beating on the coupling as well as the motor itself. I suspect premature motor failure around the shaft seals. Using belts and pullies will isolate the motor somewhat from the shock of the grindre cutting away at the stump. The belts will absorb most of the shock. My grinder is gear driven thru a right angle gearbox and uses 3 b series belts to drive the grinding wheel. The gear box only has one bseries belt belt between it and the engine. My straw blower has a similar belt hookup to reduce shock from the frail chains and the engine as it beats the straw. I have to replace the belts every now and then, but they are a lot cheaper than replacing couplings and motors. Belts are relatively cheap and I keep spares with me when I am on a job.

 

[woodlandfarms]

Basically loss of power. I made a few calls to Bobcat and such and while damage to Hydraulic motors is a consideration, the loss of power through belt is too much.

I found one geared drive, but all I have seen in the bobcat type hydrualic are direct drive.

 

[J_J]

Then connect your hyd motor through a gear box, and let the gear box handle the load.

If a gear box can turn a bush hog, is should be able to handle the load from a stump grinder.

Surplus Center

Surplus Center

 

[mikehaugen]

If the cutting wheel is self-supporting on it's own bearings and coupled to a motor that is aligned properly to the shaft, there will be no more load on the motor than any other suggestion here. The object is to keep the load inline and completely rotational, and eliminate side-loads. Belts will create a side-load and cause bearing/seal failures if it is not designed to be belt driven (literature should specify this... most say should be coupled). Basically you should mount the cutting wheel with a bearing on each side of it to bear the load, then mount motor independently with coupler between. You should be able to remove the motor without affecting the cutting wheel at all.

Depending on how you plan to mount the motor, slotted holes and shimming will allow you to perfectly align the coupler. If it is face-mount then make a right-angle bracket with slotted holes on the adjacent side of the motor to allow for alignment.

 

[woodlandfarms]

Thanks Mike. That is my basic design right now and how I see most of the grinders built. I have seen some with direct connect (Blade directly attached to motor) but that seems like a recipe for rebuilding your motor frequently. But the guys who have them say they do not have that issue.

 

[muddstopper]

I will make another suggestion and that is to use a OHLA coupling. These are designed to have the motor bolted to them, and the OHLA bolts to the frame. the OHLA shaft sizes to couple to the cutter wheel, or whatever, and is made to support heavy sideloads. Direct mount of motor to OHLA eliminates alignment and side load issues with mounting the motor.
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