DIY Roller vibratory conversion

[Mrphoenix80]

SO I needed a lawn roller. I went and picked one up today. After about 3 or 4 seconds of deep thought. I was thinking about making it vibratory. Quick search and I found some 12v motors with 200lbs of force.
The builder stated the roller is 1100lbs empty and almost 2300lbs filled with water. I was thinking if I added 2 of these above the axle that could give the vibration I want. This will help to compact gravel and milling for my driveway as well as smoothing ruts in the lawn.

What are your thoughts? Has anyone here done this?

 

[Rustyiron]

I'm wondering if you load the roller with water, will the added vibrator be enough to overcome the weight of the water adding any benefit?

 

[ponytug]

The issue with two separate sources is that the vibration won't be in synch, and will be cancelled out about half the time, and almost all of the time the net force will be trying to turn/yaw your roller. That is going to be hard on everything.

The even bigger issue is that the little 12V vibrators won't generate the force that you need. You need (lots of) power to move enough weight to counteract a substantial portion of the roller weight.

To me, it seems a little heavy for lawn rolling, but soils can be quite different.

For the driveway, just roll it in small layers with multiple passes, i.e. don't scrape up six inches and expect this to compact it solid. If it is a new build driveway, I would rent a commercial unit. You would get great results faster.

All the best,

Peter

 

[CADplans]

You gotta possibly get out a physics book to follow my thought,, but,,

FORCE = 1/2 M X V(squared) squaring a number is WAY better than doubling,,

if you double the weight of the roller, the force doubles,,
If you double the velocity,, the force goes up 4X

If you triple the weight, the force goes up 3X
If you triple the speed that you pull the roller, the force goes up 9X

Before you engineer a vibratory mechanism,, simply pull the roller as fast as safely possible.

I have a piece of ductile iron pipe made into a roller,, full of gravel, and concrete.
When you pull it at 8mph,, rather than 2mph,, the driveway gets FLAT in a hurry.

In high gear, wide open, the roller easily will drive down a rock half the size of a football

Pulling the roller at "mowing speed" the roller just rolls up and over the same rock.

Let physics do the work, rather than spending money on something that "might, or might not" work.

 

[ponytug]

@CADplans has a small typo above, (I know he knows this) and I am definitely splitting hairs, but kinetic energy is 1/2mv**2. @CADplans post is right on the money otherwise. A fast moving roller will do a faster job, and a better one, than a slow moving roller.

All the best,

Peter

 

[4570Man]

Most vibratory rollers or anything else that vibrates just spins an out of balance flywheel. Spinning the wheel is easy. Getting bearings and shafts to hold it will be more costly.

 

[CADplans]

Most vibratory rollers or anything else that vibrates just spins an out of balance flywheel. Spinning the wheel is easy. Getting bearings and shafts to hold it will be more costly.

and, if you spin any significant amount of weight out of balance, it is gonna need a LOT more power than a 12 volt motor,,

Maybe a 10 horsepower hydraulic motor, that costs over $1,000,, to start making an effect.

 

[Smokeydog]

Small ride on compactors have hydraulic vibrators in their rollers, not on the frame. Takes considerable HP to quickly pick up the machine and drop it. Apply enough force that they slide sideways with a little side slope like most of my driveway. Have to occasionally switch one or both rollers off to stay on the gravel road. Do compact well. Driveways tend to slope lot more than roads around here. A small vibrator will not give much compaction satisfaction.

 

[MossRoad]

I didn't realize it was so complicated...

 

[ponytug]

@MossRoad, You are so right. It does get complicated. Once you get into it, the forces, and energy required are substantial, which rolls over into the design/engineering of sufficiently large drive motors, shafts and bearings. A roller with a 1,000 lb offset weight flywheel has to have a hydraulic motor large enough to raise that flywheel 20-80 times per second.

Commercial flatbed versions often have two weights whose relative offset/phase angle can be adjusted to control where the thrust vector is pointed. That makes them easy to move forward, or reverse. The engineering on those weights is pretty creative. Then there are the vibrators used at the end of excavators to drive piles

The small vibrators are great for screens, and moving loose product along a chute, but I think are really too weak for compaction.

And then you get into the complexities of soil type and condition, and how to adjust it to achieve the compaction goals. "Never bite off more than you can chew" really seems to apply there, as smaller lifts of soil can be fully compacted more readily than large ones which may never fully compact.

I looked for a used vibratory roller for awhile, and gave up; I came to the conclusion that they are such workhorses that a) the price stays up, as anyone with one earns good money with it, b) owners only give up on the machine when the repairs are more than a working machine (at which point why would you buy it?) and c) the parts to make one are pretty much at least the cost of a used one...so all pretty much the same cost, at least around here.

All the best,

Peter