Hydraulic Chipper/Shredder Project

[BobRip]

To protect the hyd motor, a relief valve should be used across the motor.

Thanks J_J, that's what I was looking for. Remember you are not trying to protect just the hyd motor, you also want to protect the chipper. Chippers are subject to a lot of abuse.

 

[smartguyz]

Wow, this is great info. I've been away for so long, I've forgotten how much you guys know about stuff like this. Thanks for chiming in so quickly to advise a 'prodigal' TBN member. I'm going to run some more calculations and see if I can acquire that broken chipper/shredder.

-Rob

 

[Gravy]

I'd try to find a 3600rpm motor and direct couple it. Any sort of gearing or belt drive wastes some power due to frictional losses.

 

[J_J]

A direct drive hyd motor using 8 GPM, and turning at 3600 rpm, will have a displacement of .513 cu in. The torque on that motor using 2500 psi, will only be 204 in lbs. That does not seem like enough torque.

One needs to look at the torque produced by a 11 or 14 HP gas engine to compare.

 

[MossRoad]

A direct drive hyd motor using 8 GPM, and turning at 3600 rpm, will have a displacement of .513 cu in. The torque on that motor using 2500 psi, will only be 204 in lbs. That does not seem like enough torque.

One needs to look at the torque produced by a 11 or 14 HP gas engine to compare.

That's why I asked would it be better to use a larger displacement motor running at lower RPMS for the added torque and then put a larger pulley on it to get the chipper shaft up to the proper RPMs.

 

[BobRip]

That's why I asked would it be better to use a larger displacement motor running at lower RPMS for the added torque and then put a larger pulley on it to get the chipper shaft up to the proper RPMs.

The larger pulley would raise the speed, but lower the torque at the chipper shaft. There is no such thing as a free lunch.

 

[MossRoad]

The larger pulley would raise the speed, but lower the torque at the chipper shaft. There is no such thing as a free lunch.

I agree about the free lunch, but which of the three choices would be better?
1. A smaller displacement high speed hydraulic motor with a small pulley.
2. A larger displacement low speed motor with a big pulley.
3. A perfectly sized hydraulic motor (according to the calculator at Surplus Center) with either a direct connection or 1:1 pulleys.

 

[ponytug]

Repeat after Bob, while clicking your ruby slippers together;
"There is no place like home, there is no place like home..."

Or such a thing as a free lunch.

I would opine that for a chipper, all the below options are equivalent, except #3A. The directly connected motor will be subjected to extensive shock loading, and will need to be designed for it.

The v-belts and slippage will help shield the motors in the other cases.

The chipper speed is fixed, as momentum is important, and one would like to operate at the design knife velocity.

The math suggests that the 425 has more than enough PTO power to run this chipper.

All the best,

Peter

I agree about the free lunch, but which of the three choices would be better?
1. A smaller displacement high speed hydraulic motor with a small pulley.
2. A larger displacement low speed motor with a big pulley.
3. A perfectly sized hydraulic motor (according to the calculator at Surplus Center) with either a direct connection or 1:1 pulleys.

 

[BobRip]

I agree about the free lunch, but which of the three choices would be better?
1. A smaller displacement high speed hydraulic motor with a small pulley.
2. A larger displacement low speed motor with a big pulley.
3. A perfectly sized hydraulic motor (according to the calculator at Surplus Center) with either a direct connection or 1:1 pulleys.

I would go with the 1:1. That if needed it's easier to go up or down in speed.

 

[J_J]

With a hyd motor, the rpm will decrease with an increase in displacement, with a set GPM. Perhaps a comprise could be made to lower the rpm for more displacement, and more torque. The chipper is going to chip, at whatever speed, but there is a desired speed for efficient chipping. The 3ph Bearcat that I have not only chips, but shreds. The rpm of the PTO is increased, but I don't know the rpm.

Maybe something like this.

https://www.surpluscenter.com/item.asp?UID=3516020513353108&item=9-7073-100&catname=hydraulic