MossRoad
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Hydraulic Chipper/Shredder Project
- Thread starter smartguyz
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smartguyz
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Hi David,
I'm having trouble trying to get the spec on the RPM of the original engine. According to this spec table, the newer units will do 2714 "chipping hits per minute".
MacKissic Inc.
I believe that there is only 1 chipper blade on the chipper. I am making the assumption that the pulleys are in a 1:1 ratio.
This 'see-through' photo of a demo unit seems to imply that there is only 1 chipper blade.
A & D Reisman Lawn Service - MacKissic MightyMac
Thus, it seems that a 2700 RPM is a decent guess. I could always call the factory and talk to an engineer who would know for sure.
-Rob
I'm having trouble trying to get the spec on the RPM of the original engine. According to this spec table, the newer units will do 2714 "chipping hits per minute".
MacKissic Inc.
I believe that there is only 1 chipper blade on the chipper. I am making the assumption that the pulleys are in a 1:1 ratio.
This 'see-through' photo of a demo unit seems to imply that there is only 1 chipper blade.
A & D Reisman Lawn Service - MacKissic MightyMac
Thus, it seems that a 2700 RPM is a decent guess. I could always call the factory and talk to an engineer who would know for sure.
-Rob
MossRoad
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Yeah, the shredder is a bunch of hammers flailing around while the chipper is usually one or two blades mounted on a heavy flywheel.
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smartguyz
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Hi guys,
Well, I picked it up. Here are some photos. The 5HP Briggs and Stratton gas engine is just toast. I bought a few parts and tried to resurrect it, but I really don't think it will be worth it. I've already spent $25 on parts, and it will probably take another $50 before I finish IF I can get the gas motor working again. As you can see by the photos, it's a wreck. I don't think I've ever seen so neglected an engine. It's clear it sat outside for years before I picked it up today. Water in the gas tank, rust everywhere, ick! When I pulled out the 'foam' air filter, it was like styrofoam, and was falling apart in my fingers. Ugh! It's so corroded that the pushrod for the ignition points is rusted and stuck inside the engine - that's why there's no spark - the points don't have anything to ride the camshaft and break the points open, if you are familiar with how these engines work. A mess. I could buy the breakerless ignition and work around this problem, I'm not convinced its worth it.
Anyway, I picked up the whole contraption for $70, and despite the neglect, the shredder itself is quite sturdy. It is made of sheet steel with hefty steel hammers and a thick steel filter grate. It's sturdy, like a PT! A similar item from MacKissic today runs around $2000, although newer units have a chipper as well as the shredder.
You can see that if I take out the gas powerplant, and put in a hydro motor with the centrifugal clutch-pulley on it, then it should work. I'll need to fabricate some kind of sliding mount for the hydro motor (the v-belt tension is adjusted by moving the gas engine back and forth on its engine platform.) and I'll need to drill off the pulley (it's rusted on the gas engine) and tap it and reattach to the hydro motor.
The photos speak for themselves.
I admit it looks pretty rough, but it's all surface rust, and the mechanics are sound. The bearings on the shredder have no play and spin freely. The hammers actually don't look very used. The wear is completely due to exposure to elements.
Your input is solicited.
-Rob
Well, I picked it up. Here are some photos. The 5HP Briggs and Stratton gas engine is just toast. I bought a few parts and tried to resurrect it, but I really don't think it will be worth it. I've already spent $25 on parts, and it will probably take another $50 before I finish IF I can get the gas motor working again. As you can see by the photos, it's a wreck. I don't think I've ever seen so neglected an engine. It's clear it sat outside for years before I picked it up today. Water in the gas tank, rust everywhere, ick! When I pulled out the 'foam' air filter, it was like styrofoam, and was falling apart in my fingers. Ugh! It's so corroded that the pushrod for the ignition points is rusted and stuck inside the engine - that's why there's no spark - the points don't have anything to ride the camshaft and break the points open, if you are familiar with how these engines work. A mess. I could buy the breakerless ignition and work around this problem, I'm not convinced its worth it.
Anyway, I picked up the whole contraption for $70, and despite the neglect, the shredder itself is quite sturdy. It is made of sheet steel with hefty steel hammers and a thick steel filter grate. It's sturdy, like a PT! A similar item from MacKissic today runs around $2000, although newer units have a chipper as well as the shredder.
You can see that if I take out the gas powerplant, and put in a hydro motor with the centrifugal clutch-pulley on it, then it should work. I'll need to fabricate some kind of sliding mount for the hydro motor (the v-belt tension is adjusted by moving the gas engine back and forth on its engine platform.) and I'll need to drill off the pulley (it's rusted on the gas engine) and tap it and reattach to the hydro motor.
The photos speak for themselves.
I admit it looks pretty rough, but it's all surface rust, and the mechanics are sound. The bearings on the shredder have no play and spin freely. The hammers actually don't look very used. The wear is completely due to exposure to elements.
Your input is solicited.
-Rob
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smartguyz
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You already know that the PT425 main PTO is rated at 8GPM@2500PSI.
You have to determine how many RPMs you want the chipper shaft to turn at.
The hydraulic calculator on the Surplus Center site will take your flow (8gpm) and your desired RPM (3600 or 1800 or whatever you choose) and calculate the size of the hydraulic motor that you need to achieve the desired RPMs. This, of coursed, is based on 1:1 pulleys.
For instance, 8GPM flow and 3600 RPM shaft speed will require a 0.5 cubic inch motor displacement while 8GPM flow and 1800 RPM shaft will require 1.0 cubic inch motor displacement. However, you could change that by gearing system up or down with pulleys.
For instance, lets say your 1" hydraulic motor tuns at 1800RPM and you want to turn the chipper shaft at 3600 RPM. You would need to put a pulley on the chipper shaft that is 1/2 the diameter of the pulley on the hydraulic motor.
So, the question is, what do you need?
A larger displacement hydraulic motor turning at less RPMS geared up with pulleys...
A normal displacement hydraulic motor turning at the same RPMs with no gearing of pulleys....
A smaller displacement hydraulic motor turning at higher RPMS geared down with pulleys....
That is the question I would like the TBN membership at large to answer... should we use a larger displacement motor or a smaller displacement motor?
OK, so Moss (per normal), gives us a baseline for calculating this project. Here are the inputs. As you can see from the photos,
- The engine pulley has a diameter of 3.5".
- The shredder pulley has a diameter of 5"
This means that the shredder hammermill is rotating at a speed of 3.5/5 of the engine/motor speed. This calculates out to 70% of the engine speed.
So, if the typical Briggs and Stratton 5HP Horizontal Shaft engine turns at 3600 RPM, a 70% reduction would give 2520 RPM. That's pretty close to the estimate from the spec sheet of 2714 RPM. I wasn't real exact on my measurements of the pulley diameter, and I could easily be off by 5%. So, I think we can go with a 75% ratio.
OK, so that does mean that we want a hydro motor that turns around 3600 RPM or thereabouts.
Where's that nifty hydro motor calculator on the website?
-Rob
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smartguyz
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Allrighty then.
According to the equations on the SurplusCenter.com,
Hydraulic motor speed (RPM) = 231 x GPM / motor displacement (in3/rev)
So,
3600 RPM = 231 x GPM / motor displacement (in3/rev)
GPM / motor displacement (in3/rev) = 3600 / 231 = 15.58 cubic inches/rev
Given a target RPM of 3600, 2500 PSI and 8GPM from the PT425, this means I need a
0.5 cubic inch motor, which will give us 3696 RPM at 8GPM.
Also, this results in 199 inch-pounds of torque at 2500 PSI and 14 HP.
OK, looking at Surplus Center, they don't sell anything that looks like that. A 0.5 cu in hydro motor is small and spins really fast with low HP and torque.
What am I doing wrong?
The motor pulley has an integrated centrifugal clutch, which kicks in when the motor gets to a certain speed. My understanding is that this makes it easier to pull-start the chipper. We could move to a 5" diameter pulley, and eliminate the centrifugal clutch, since we don't have that issue with the PT.
Ideas?
-Rob
According to the equations on the SurplusCenter.com,
Hydraulic motor speed (RPM) = 231 x GPM / motor displacement (in3/rev)
So,
3600 RPM = 231 x GPM / motor displacement (in3/rev)
GPM / motor displacement (in3/rev) = 3600 / 231 = 15.58 cubic inches/rev
Given a target RPM of 3600, 2500 PSI and 8GPM from the PT425, this means I need a
0.5 cubic inch motor, which will give us 3696 RPM at 8GPM.
Also, this results in 199 inch-pounds of torque at 2500 PSI and 14 HP.
OK, looking at Surplus Center, they don't sell anything that looks like that. A 0.5 cu in hydro motor is small and spins really fast with low HP and torque.
What am I doing wrong?
The motor pulley has an integrated centrifugal clutch, which kicks in when the motor gets to a certain speed. My understanding is that this makes it easier to pull-start the chipper. We could move to a 5" diameter pulley, and eliminate the centrifugal clutch, since we don't have that issue with the PT.
Ideas?
-Rob
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smartguyz
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OK. Still thinking...
I could do the following:
1) Use a 1 cu in hydro motor, as suggested: https://www.surpluscenter.com/item.asp?UID=3516020513353108&item=9-7073-100&catname=hydraulic
2) Use a 7.5" pulley on it. Coupled to the 5" driven pulley, this will give us a speed up in RPM making the 1800 RPM of the motor become 2700 RPM.
3) The hydro motor has an output rating of 10HP. This is a massive 2x increase in HP from the 5HP Briggs & Stratton, and will make it just like the newer units, which have similar HP engines.
4) I can use a plain pulley instead of a centrifugal one, since we're not worried about needing to start the engine by hand.
So... Question time (thanks for your patience - I feel like such a newbie):
A) Does this make sense?
B) If so, what kind of mounting bracket can I purchase or easily fabricate?
C) What kind of relief valve should I use? I browsed the SurplusCenter site, and it is confusing to me.
D) What kind of hoses and couplers do I need?
Any other ideas? Am I insane to try this?
-Rob
I could do the following:
1) Use a 1 cu in hydro motor, as suggested: https://www.surpluscenter.com/item.asp?UID=3516020513353108&item=9-7073-100&catname=hydraulic
2) Use a 7.5" pulley on it. Coupled to the 5" driven pulley, this will give us a speed up in RPM making the 1800 RPM of the motor become 2700 RPM.
3) The hydro motor has an output rating of 10HP. This is a massive 2x increase in HP from the 5HP Briggs & Stratton, and will make it just like the newer units, which have similar HP engines.
4) I can use a plain pulley instead of a centrifugal one, since we're not worried about needing to start the engine by hand.
So... Question time (thanks for your patience - I feel like such a newbie):
A) Does this make sense?
B) If so, what kind of mounting bracket can I purchase or easily fabricate?
C) What kind of relief valve should I use? I browsed the SurplusCenter site, and it is confusing to me.
D) What kind of hoses and couplers do I need?
Any other ideas? Am I insane to try this?
-Rob
Last edited:
J_J
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Just to clear things up, since it doesn't have a side chute, that is only a shredder, It does not chip. I thought you had a later model of the one that I had. I have used both a gas engine, and electric on the shredder and it ran so so. I believe the blades can be reversed. I think you will have to sacrifice some rpm for torque. These people also have some of the products you might need.
Bailey Hydraulic Cylinders Manufacturer
You will need 3000 psi hoses, some QD's, and a relief valve for the motor, and QA plate for the shredder.
https://www.surpluscenter.com/item.asp?UID=2100020706320710&item=1-3242&catname=hydraulic
If you want variable speed, you can add a flow control valve.
https://www.surpluscenter.com/item.asp?UID=2100020706320710&item=9-4169-10&catname=hydraulic
https://www.surpluscenter.com/item.asp?UID=2100020706320710&item=9-6135-50-H&catname=hydraulic
Good luck.
Bailey Hydraulic Cylinders Manufacturer
You will need 3000 psi hoses, some QD's, and a relief valve for the motor, and QA plate for the shredder.
https://www.surpluscenter.com/item.asp?UID=2100020706320710&item=1-3242&catname=hydraulic
If you want variable speed, you can add a flow control valve.
https://www.surpluscenter.com/item.asp?UID=2100020706320710&item=9-4169-10&catname=hydraulic
https://www.surpluscenter.com/item.asp?UID=2100020706320710&item=9-6135-50-H&catname=hydraulic
Good luck.
3238dpw
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I am following this thread with great interest. As you can see I have the same project going on and I am happy to let Rob figure it all out for me. Actually I have been thinking about mounting it on a Garden Tractor like the last pic. Not sure. Either way it is one less engine to worry about.
Unfortunatly my project is a little low on my list of things to do. So I am not going to be working on it for a little while.
Actually I have been thinking about mounting it on a Garden Tractor like the last pic. Not sure. Either way it is one less engine to worry about. Unfortunatly my project is a little low on my list of things to do. So I am not going to be working on it for a little while.
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MossRoad
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As J_J mentioned, it appears to be only a shredder, not a chipper/shredder.
Having operated a shred only unit in my youth and I gotta tell you I would not proceed with the project. Burning fuel to shred leaves that will rot on their own with little labor on my part never made sense. My dad made me operate the unit for days on end each fall. Rake, haul, dump, pick up by hand, put in shredder, repeat.
I finally convinced him to push the leaves into a corner of the yard and let them rot into compost. I still do that in my yard to this day, only with a twist. I mow the leaves with my PT, which shreds them, and I TOW a Brinley lawn sweeper cart behind the PT as I go. The leaves get shredded AND picked up in the same motion. Then I dump them in a corner of my yard and use them in flower beds, garden, etc... as needed.
I don't mean to be a downer. If you have a use for the shredder, I think you have the perfect donor unit there. Low, low cost and should be easy to swap out the gas motor for a hydraulic motor.
I think your calculations are correct. You have to decide on the size of the motor and pulley. You might want to pose the question in the hydraulics forums as to if it is better to use gear up, gear down, or 1:1 on the motor and see if anyone can give you an advantage for either way to achieve the proper RPM of the shaft.
Having operated a shred only unit in my youth and I gotta tell you I would not proceed with the project. Burning fuel to shred leaves that will rot on their own with little labor on my part never made sense. My dad made me operate the unit for days on end each fall. Rake, haul, dump, pick up by hand, put in shredder, repeat.
I finally convinced him to push the leaves into a corner of the yard and let them rot into compost. I still do that in my yard to this day, only with a twist. I mow the leaves with my PT, which shreds them, and I TOW a Brinley lawn sweeper cart behind the PT as I go. The leaves get shredded AND picked up in the same motion. Then I dump them in a corner of my yard and use them in flower beds, garden, etc... as needed.
I don't mean to be a downer. If you have a use for the shredder, I think you have the perfect donor unit there. Low, low cost and should be easy to swap out the gas motor for a hydraulic motor.
I think your calculations are correct. You have to decide on the size of the motor and pulley. You might want to pose the question in the hydraulics forums as to if it is better to use gear up, gear down, or 1:1 on the motor and see if anyone can give you an advantage for either way to achieve the proper RPM of the shaft.
