Sickle Attachment

[NCMau]

I am in the process of making a vertical sickle cutter attachment for my tractor by using a modified transmission and a 42" bar from a Gravely walk-behind tractor. This bar will be mounted in front of the loader arms and driven by a hydraulic motor.

Since I recently modified the tractor with a PTO pump to drive the loader, I will be using the on-board pump to drive the sickle bar. The hydraulic fluid will be supplied by the existing tractor selector valve, which I no longer use.
Just made a temporary connection from this valve to the sickle bar to determine if it is compatible with what I have.

The on-board pump is probably 4 or 5 GPM, the motor which I have on hand has a max of 15 GPM and a speed of 750 RPM. With this "no load" setup seems to operate just fine. The 3pt lift is out of the operation and I can control the speed fro 0 to max with the position control.

I was planing to get a flow control valve, but with this setup, I don't see why I would need it, unless it is for the reason that the flow control valve would have a built-in PRV. But then again, the on-board pump has a PRV and the sickle motor is the only device operated by the pump.

My Question: Is this flow control valve really necessary?

 

[J_J]

If the hyd motor uses 15 GPM for a 750 rpm speed, based on cu in displacement, and your tractor only puts out 5 GPM, then the hyd mtor wil run at a speed equal to the 5 GPM which will be about 1/3 , or 250 rpm.

If the sickle bar cuts OK, then all is well, and the tractor lever needs to be fully open or locked open with a bungee.

If the pressure rating on the hyd motor is about 3000, then a tractor relief setting of 2950 will relieve the pressure on the hyd motor if it develops that pressure.

 

[NCMau]

From what I can determine so far, the speed is perfect, actually a little too fast without restricting the fluid. Once the load is applied, I should be able to have full control. I just hope the equivalent torque will be sufficient.
Waiting for some fittings from SC.