# can a 252 stump grinder be modified to move faster???



## Treeinnovator (Aug 29, 2006)

the current Vermeer 252 stump grinder is VERY slow. has anyone out there seen a faster or modified version? 
the speed control screw nob is adjustable but stops after a little bit of twisting. obviously there's something adjusting the gears with each twist. what if the stopping mechanism can be bypassed so that it will continue to speed up? any thoughts on this?


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## Plyscamp (Aug 30, 2006)

The speed control knob is nothing more than a bypass valve. It will never increase your speed as it allows hydraulic oil to bypass the drive motor & return to the hydraulic tank.

I have modified my units to increase the ground speed by changing the pulley diameter at the hydraulic pump. Be aware that this will also increase the swing speed on the cutting head. If my memory serves me correctly the stock pulley is approximatly 5 inches in diameter. Relace it with a pulley that is 3 inches in diameter and replace the belt with a 4L250. This will increase the ground speed about 40 percent. A 3.5" pulley will increase it about 30 percent.

Hope this helps.


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## Treeinnovator (Aug 30, 2006)

Plyscamp said:


> The speed control knob is nothing more than a bypass valve. It will never increase your speed as it allows hydraulic oil to bypass the drive motor & return to the hydraulic tank.
> 
> I have modified my units to increase the ground speed by changing the pulley diameter at the hydraulic pump. Be aware that this will also increase the swing speed on the cutting head. If my memory serves me correctly the stock pulley is approximatly 5 inches in diameter. Relace it with a pulley that is 3 inches in diameter and replace the belt with a 4L250. This will increase the ground speed about 40 percent. A 3.5" pulley will increase it about 30 percent.
> 
> Hope this helps.



that sounds great !!! alot of people on here could use a faster sc252. did you ever take photos of the modifications your talking about?


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## Beast12 (Aug 30, 2006)

The slow moving 252 is about the only complaint my dad has with that grinder. I can see why it moves slow (safety/tipping issues) but it should be made to go a bit faster.

-Matt


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## Plyscamp (Aug 31, 2006)

I have not taken photo's of the conversion as it is a straight forward swap. You simply remove the old pulley from the pump (Located inside the Clutch Cover)and replace it with the new pulley. Add the new shorter belt and your good to go. The only problem you may have is finding a pulley with a 9/16" inside diameter hole (1/2" and 5/8" I.D. pulleys are standard stock) My bearing house was able to match it with a 2 piece taper lock pulley. Bearing house I used is Kayman Bearing. 

From a tipping stand point add the Dual Wheel Kit it's the best improvment you can make on the SC252. If you need to get through a gate it's only 4 bolts to remove them.


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## Liston (Sep 3, 2006)

*smaller sproket*



Treeinnovator said:


> the current Vermeer 252 stump grinder is VERY slow. has anyone out there seen a faster or modified version?
> the speed control screw nob is adjustable but stops after a little bit of twisting. obviously there's something adjusting the gears with each twist. what if the stopping mechanism can be bypassed so that it will continue to speed up? any thoughts on this?



Get a smaller chain sproket for your axle from your local chain supplier
this will speed up your drive, BUT you will loose some torque on steep climbs.


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## Ekka (Sep 3, 2006)

After using a Kanga I find those slow too, even the RG range is slow ground travel, sounds like easy mods though.

By changing the pulley dia that increases hydro oil pressure/flow doesn't it?

Any possible adverse effects like too much pressure or anything?


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## Bigstumps (Sep 3, 2006)

Ekka said:


> After using a Kanga I find those slow too, even the RG range is slow ground travel, sounds like easy mods though.
> 
> By changing the pulley dia that increases hydro oil pressure/flow doesn't it?
> 
> Any possible adverse effects like too much pressure or anything?



Increases flow not pressure. Flow will give you speed but will also speed up the other functions. Increased flow can equal increased heat in the hydraulic system. As you open up the swing speed control and allow more oil to bypass, that bypassed oil goes right back through the adjustable oriface back to tank. The pressure side of this oriface is at the same pressure as whatever it is taking to swing the head, the other side of this adjustable oriface is at basically zero. This difference in pressure - referred to as pressure drop across the oriface - produces heat. Depending on the this pressure differential and the amount of flow going through it can be a lot of heat.

You would have to try it to find out. You're not going to blow anything up because you haven't increased pressure but keep an eye on the heat.


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## p goble (Sep 3, 2006)

*What about the auto sweep function*

will the increased pressure and flow effect the auto sweep. Looking at the hydraulic system it's obvious that all the flow for sweep goes thru the auto sweep module


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## Plyscamp (Sep 4, 2006)

I made the speed modifications on my original 252 about 1,000 hours ago and have had no heat or pump problems. 

As far as the Auto Sleep function I disconnected it by pulling the fuse 2 days after I bought it. My old SC206 would grind more wood than the SC252 with Auto Sleep. You can control side to side sweep speed, up and down speed and ground speed with the control levers, there all variable speed.


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