DIY/ build along hydraulic Shredder

[HainesNYT]

I'm still working on the exact measurement for clearance between the underside of the deck and the top of the blade carrier...ensuring there is enough room for the blade bolts/nuts to not hit the bottom of the deck as well.

I have decided to go with stacking 1/2" discs in a pyramid form to gain clearance. This will also add plenty of weight which will help with the "flywheel" idea; however, I know there is a fine line between heavy and too heavy. I am weighing all the parts as I go so I should have a fairly good idea what this thing will weigh.

[dkmossoak]

In for the long haul. Can you explain why you selected or wanted a certain gear ratio.

[HainesNYT]

I just spent 30 minutes typing the how's and why's...and tapacrap crashed . I'll respond again tonight from the computer

[dkmossoak]

ok thanks

[HainesNYT]

In for the long haul. Can you explain why you selected or wanted a certain gear ratio.

I have done tons of research and asked lots of questions...so, everything I put here is as factual as I have been able to ascertain and some is my opinion.

It is all about Blade Tip Speed (BTS) measured in Feet Per Minute (FPM). There are some folks out there that believe your BTS should be based on the work/size of material you are cutting...like the larger the diameter/slower & faster for grass. Personally I believe the faster the better and feel that you are trying to cut/chip not clobber the material. I also think the faster the BTS the smaller the mulch will be as it gets hit/cut more often. I have seen everything from about 11,000-19,500 FPM.

There are "direct-drive" setups that will be a bit different....but I am building a deck with a right angle gearbox, so we will focus on that style.

First off, tractors commonly come with 540RPM or 1000RPM PTO shaft...so all the tractor implements are pretty much based off of those two figures. Skid Steer Loaders (SSL) have a wide verity of hydraulic flow rates, measured in Gallons Per Minute (GPM). They are commonly divided into Standard Flow and Hi-Flow .......BUT, it varies greatly in those two categories. You will find that many SSL attachment manufactures will offer 2-3 models of the same attachment because of the difference in GPM. This project is being built for my neighbors Bobcat which has 15GPM.

Hydraulic motors are measured in Cubic Inches Displacement (CID) and the smaller the CID, the less torque it will have, but the faster it will spin. [Now, this may not be true for all hydraulic motors, but it is for the type I am using and seems pretty close to across the board for what I have learned...if anybody knows differently, feel free to enlighten.] Based on the input GPM and the CID will give you the output RPM of the motor. There are online calculators to help you dope these numbers out.

Right angle gear boxes for shredders are Speed Increasers. You will take the input RPM from the hydraulic motor and multiply it by the ratio of the gear box to get your Final Drive RPM. There is a balance to be had between torque and speed, based on the GPM of your machine.

Blade & Blade carrier circumference is needed to compute the FPM. Get the diameter/ from blade tip to blade tip and multiply by 3.14 for circumference, then divide by 12 since we are working in feet. Multiply that by the final drive RPM and you have your BTS in FPM.

This project:
15GPM Machine
4.95CID motor (700rpm)
1:1.46 Omni Gear RC-71 (75-100hp gearbox) (1022rpm)
I believe my Blades & Carrier will put me at 58" diameter/15.18' Circumference, 15.18 X 1022RPM= 15,514 FPM

I have a Bradco 72" cutter that I modified & converted from a hi-flow attachment to a standard-flow. I am pushing it with 19GPM, turning a 9.95CID motor, which is turning a 1:1.93 Gearbox...my FPM is 16,195. I wish it was a bit faster. I do feel like the torque is adequate. When the carrier stops, it takes a second or so to spin back up to speed. It seems to stop or slow more quickly than I would like, and I equate that to the standard style stump-jumper...not a flywheel-like blade carrier, so there is less "stored energy". If this current project works out well, I will build a new blade carrier for the Bradco.

*I wanted to get a slightly larger hydraulic motor for the Bobcat Cutter and run 1:1.93 ratio gearbox, but I couldn't locate a gearbox in the larger horsepower rated models....so this is why I am running 4.95CID/1:1.46.


Clear as mud?

[HainesNYT]

Here you can see how high this gear box sits...it may have been better to build a deck from scratch.



Here is where the deck curves and I have to ensure there blades are below that spot.

[HainesNYT]

This deck was originally supposed to be boom-mounted and so the front and back of the deck are open....I have welded in a piece of 1/4" plate to close off the back-end..which is where the operator will be sitting. I don't have any warm-fuzzies, so I'm going to double it, making it 1/2" thick.

[HainesNYT]

[dkmossoak]

Thanks for taking the time to explain the gear ratio aspect. Very understandable. Is there a shear bolt or some kind of safety feature to keep from destroying your equipment?

[HainesNYT]

Thanks for taking the time to explain the gear ratio aspect. Very understandable. Is there a shear bolt or some kind of safety feature to keep from destroying your equipment?

Being this is hydraulic, the fail safe will be in the plumbing. I'm using a double relief cushion valve, and a one way check valve. I'll post when I install them as well.

[HainesNYT]

Picked up the main plate for the blade Carrier. My original plan was for this to swing two blades...figured I'd get the opposite corners drilled incase we decided to run 4 blades....now I realize the blades would hit each other if they contacted something big. I will show a picture of that later.

When I had the CNC plasma work done, I gave them the wrong measurements for the blade holes. The bolts have a step to them that I completely forgot to account for. I have made a bushing to fill the gap around the bolts, using a Cat 2 to 3 bushing. Cut 1/2" thick and notched for the bolt "tab". These will be welded in & ground flush.

[HainesNYT]

[HainesNYT]

Here is the problem with trying to run 4 blades. If the carrier was a tad larger it wouldn't be a problem (or the blades a tad shorter).

[HainesNYT]

Here is the top-side of the blade carrier. The hub is yet to be welded in place. Letting it cool a bit before welding again.
* the pipe is just for alignment

[woodsman08]

Really enjoying this thread. Thanks for sharing