Brush chipper

[nirias]

I have a Vermeer 625 chipper with a troublesome motor - I spend more time tinkering with the motor than chipping. Rather than replace the motor for $2K I was thinking of welding a quick attach mount to the side of the chipper and replacing the 20 hp gas motor on the chipper with a hydraulic motor. That way I could move it into tighter spots in the forest than I can by towing and I can just run the chipper off my bobcat hydraulics (I have high flow). Has anyone done something like that? Any chance the hydraulics on the Vermeer (feed motor, hoses, control valve) cant take the 3300 psi from my bobcat?

 

[Tazza]

You can get pressure/flow reducers for the feed hydraulics, thats not an issue. If you have a Hi Flow machine i can't see you having a problem with powering the cutters with a motor, i assume you have about a 46HP engine in your machine? i don't know the losses that you will have but you should have heaps of power there. I just don't know how the motor will go with possibly being stalled, was there a clutch setup to prevent the engine stalling if it ate a branch that was too large?

 

[nirias]

You can get pressure/flow reducers for the feed hydraulics, thats not an issue. If you have a Hi Flow machine i can't see you having a problem with powering the cutters with a motor, i assume you have about a 46HP engine in your machine? i don't know the losses that you will have but you should have heaps of power there. I just don't know how the motor will go with possibly being stalled, was there a clutch setup to prevent the engine stalling if it ate a branch that was too large?

I have a s220 with 70hp I believe. The hydraulics are 37 gpm on high flow. The OEM setup on the chipper is a large double fan belt from the cutting disk to the motor. The cutting disk is around 200+ lb and does most of the cutting using rotational momentum, so after a big branch gets chipped the motor needs to build rpms again. In theory if a really large branch jammed up the cutting disk, the fanbelts would slip to protect the motor. For a hydraulic setup I was thinking of just direct coupling the hydraulic motor to the cutting disk and counting on the loader's overload valve to protect the motor should the cutting disk jam (essentially how the fan motor on my Erskine snowblower is set up). Do you think I need a separate over pressure relief rather than relying on the loader's relief valve?

 

[Tazza]

I have a s220 with 70hp I believe. The hydraulics are 37 gpm on high flow. The OEM setup on the chipper is a large double fan belt from the cutting disk to the motor. The cutting disk is around 200+ lb and does most of the cutting using rotational momentum, so after a big branch gets chipped the motor needs to build rpms again. In theory if a really large branch jammed up the cutting disk, the fanbelts would slip to protect the motor. For a hydraulic setup I was thinking of just direct coupling the hydraulic motor to the cutting disk and counting on the loader's overload valve to protect the motor should the cutting disk jam (essentially how the fan motor on my Erskine snowblower is set up). Do you think I need a separate over pressure relief rather than relying on the loader's relief valve?

I doubt it, your main relief would be set to around 3,000 PSI. If the motor stalls it will simply go over relief and not cause any problems. I'm sure others will pop their noses in and comment on it.
With 70HP i think you could use a good size motor!

 

[mllud]

I doubt it, your main relief would be set to around 3,000 PSI. If the motor stalls it will simply go over relief and not cause any problems. I'm sure others will pop their noses in and comment on it.
With 70HP i think you could use a good size motor!

Im no where as experienced with the hydraulics as Tazza on the aux.hydraulics. he knows his valves.
You would want the hyd. to relieve at somewhere near the amount of torq that the belts slip. That would probably be hard to figure.The flywheel/cutter may be over built and could take more torq than the belts are allowing.Once belts slip they slip a little easier from then on.
I think your mulcher will be a lot better once you get it set up.If you installed an adjustable check valve you could start off weak and build up to the pressure you feel the machine can handle.To much pressure may not be as forgiving as your belts.Although the flywheel/cutter most likely has a shear pin/key to protect it.
Just some thoughts. Mike

 

[nirias]

Im no where as experienced with the hydraulics as Tazza on the aux.hydraulics. he knows his valves.
You would want the hyd. to relieve at somewhere near the amount of torq that the belts slip. That would probably be hard to figure.The flywheel/cutter may be over built and could take more torq than the belts are allowing.Once belts slip they slip a little easier from then on.
I think your mulcher will be a lot better once you get it set up.If you installed an adjustable check valve you could start off weak and build up to the pressure you feel the machine can handle.To much pressure may not be as forgiving as your belts.Although the flywheel/cutter most likely has a shear pin/key to protect it.
Just some thoughts. Mike

After looking at the Eaton hydraulic motors it seems like I will need to use the drive belt arrangement anyway. The Vermeer cutting disk is supposed to spin at about 1700 or so rpms and the fastest hydraulic motors I can find are limited to around 800 rpm. So I need to use approximately 2:1 ratio pulleys and a belt to get the cutting disk up to the proper speed.

 

[bucketfork]

After looking at the Eaton hydraulic motors it seems like I will need to use the drive belt arrangement anyway. The Vermeer cutting disk is supposed to spin at about 1700 or so rpms and the fastest hydraulic motors I can find are limited to around 800 rpm. So I need to use approximately 2:1 ratio pulleys and a belt to get the cutting disk up to the proper speed.

Just couple your motor directly to the cutter disc. It'll work pretty good, but you're limited by the hydraulic flow and pressure of your hydraulics. As a rough rule of thumb, for every 1 gpm of flow, @ 3000 psi, you have 1hp. For instance, if your hydraulics have 15 gpm flow, you have 15 hp. for 30 gpm, you have 30hp. The power of the engine can't be brought to bear on your attachment, because you can't stall the engine with the aux. hydraulics. If you could, the hydraulic system would overheat. It's sorta the same speed v/s power dilema we get into in rotary cutters.

 

[TriHonu]

Just couple your motor directly to the cutter disc. It'll work pretty good, but you're limited by the hydraulic flow and pressure of your hydraulics. As a rough rule of thumb, for every 1 gpm of flow, @ 3000 psi, you have 1hp. For instance, if your hydraulics have 15 gpm flow, you have 15 hp. for 30 gpm, you have 30hp. The power of the engine can't be brought to bear on your attachment, because you can't stall the engine with the aux. hydraulics. If you could, the hydraulic system would overheat. It's sorta the same speed v/s power dilema we get into in rotary cutters.

The formula for hydraulic hp is: HP = P x F x 0.000583
P = pressure in PSI
F = Flow in GPM
(3000 psi) x (37 gpm) x 0.000583 = 64.7 HP

 

[bucketfork]

The formula for hydraulic hp is: HP = P x F x 0.000583
P = pressure in PSI
F = Flow in GPM
(3000 psi) x (37 gpm) x 0.000583 = 64.7 HP

That formula is correct, but it won't work when replacing a diesel motor with a hydraulic, don't know exactly why it's like that but that's what I've found. He, on the other hand, is replacing a gas engine, which might work.

 

[mistersweeper]

That formula is correct, but it won't work when replacing a diesel motor with a hydraulic, don't know exactly why it's like that but that's what I've found. He, on the other hand, is replacing a gas engine, which might work.

What ever happened with the brush chipper ? I am curious to find out what you did.