Stouter 3/4" steel rod - tractor drag blade?

[SteveH-CO]

I grade my driveway and road with a Massey 50 that has a drag blade. The blade angle is controlled by a 3/4" dia. steel rod about 12" long that drops through the blade frame and a sector (with several holes to control the angle) on the blade.

Every time I plow, the mild steel rods I am using bend. Then they jam the assembly, and I have to tear it all down and pound out the rod.

I have made a few of these steel rods from concrete form stakes, which obviously are not hardened. The original pin I got with the tractor sheared off.

Where can I get a 0.75", ~12" long steel rod that is harder than mild steel? I can provide photos tomorrow if that helps.

Thanks - Steve

 

[MP&C]

Look around on McMaster Carr, they have a few different easy-to-weld alloys that are hardened much more than your box store round rod variety.




https://www.mcmaster.com/#8930k11/=1ddtw55








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[Musicinabottle]

Go to a steel supply yard and get some "Stress proof" in your sizing.

 

[matt_i]

My take is this. You have a shear pin that's not tightly fitted. So it bends and jams.

The way to fix it is to tighten up the fit, get the hole and OD closer in size, and get the shearing planes closer together. If you get a harder steel rod then its going to mushroom/waller the holes oval which are not hard.

A bolt could work because the bolt tension load will keep the cleaving planes closer together, and the friction of potentially clamping the flanges will help too. What if you welded a nut under the bottom and spun it in with a T-handle welded to the top of the bolt (if you had a couple of favorite positions for the blade)? Maybe its as exotic as tapping a plate with the same radial array of holes as the sector.

O-1 will make a very hard pin, but will of course need to be tempered or else it will shatter. S-7 is a shock resistant tool steel, air hardening. Typical oxyacet and kitchen oven will get you where you need to go.

 

[LXCam]

Online metals has a good selection of materials as well as selection charts so you understand what you're buying.

 

[larry_g]

On my blade I use a hitch pin https://www.tiscoparts.com/products/HITCH @@26 LINKAGE/PINS/HITCH PINS.aspx?category=Hitch+Pins

It should be available at any farm store.

lg
no neat sig line

 

[SteveH-CO]

Thanks - you all have provided lots of excellent suggestions. The current pin is pretty tightly fitted, but the shearing planes are fairly far apart (just the way it's designed), which is why it bends.

Using a bolt and welding nuts on top of the current plate might work, so I'll consider that. Much to think about, here.

 

[BD1]

Did you ever consider a landscape rake for grading? I have a rear blade and a landscape rake. The landscape rake does a amazing job. It's really does a nicer job because of the teeth. Just saying

 

[Bretny]

Can you take pictures on the blade and pin area? I think as some point your pin will be to strong and really mess up the holes.
I use to own a cheap TSC back blade and i bent it before the pin had dammage.

Once i bought a york rake the blade sat unused...once i bought a box blade the york rake sits unused. I regrade my gravel driveway (a circle and a few turns) at least once a year with my box blade. One or two drags and its new again. Rear blades arnt the best tool for the job, i would have to drag the rear blade around for 10-15x to do what the box blade would do in 2x.

 

[FTG-05]

Thanks - you all have provided lots of excellent suggestions. The current pin is pretty tightly fitted, but the shearing planes are fairly far apart (just the way it's designed), which is why it bends.

Using a bolt and welding nuts on top of the current plate might work, so I'll consider that. Much to think about, here.

Bad design. Show us pics and let's see if we can fix the problem. Getting a stronger bolt is fixing the symptom, not the problem.

 

[SteveH-CO]

At our local Big R store (not Tractor Supply), I found a .75", 6" long tractor pin.

The design of the blade is such that there isn't much gap between the blade frame and the sector on the blade itself, so I'm not sure this is a design issue.
You can see what the blade was doing to my mild steel rod. I have not tested the new pin to see how it holds up.

 

[larry_g]

At our local Big R store (not Tractor Supply), I found a .75", 6" long tractor pin.

The design of the blade is such that there isn't much gap between the blade frame and the sector on the blade itself, so I'm not sure this is a design issue.
You can see what the blade was doing to my mild steel rod. I have not tested the new pin to see how it holds up.

I would suggest that you add a second hole like in the above picture. The S shaped piece will put the pin in double shear and help prevent bending. OR you could bolt the joint instead of pin it like now. It looks to me that things have bent and opened the gap between the sector and the frame. Bolting it will pull things back into alignment. I'd also guess that things flex a bit under load and that gap opens up more adding to the leverage that bends the pin.

If it were mine I'd bolt things together adding strength to the joint. On my blade it is set up with a second point to pin where you have the trailer ball.

good luck

lg
no neat sig line

 

[SteveH-CO]

Hmm - good idea. They should have manufactured the blade with a double-pin design, which would have been easy, since the blade is reversible and has a second set of holes.

Might be a fun engineering project to create a second pin frame.

 

[Bretny]

Double sheer may help it some. I would also try to make the sheer points closer together.

You could also make the hole in the frame closer to the back of the tractor. Use leverage in your favor.

 

[BD1]

Hard to make out . Is there pipe or tube inside where the pin goes in ? Looks like a short stub on top only. If not enlarge and drop pipe inside. That's what I think the problem is.

 

[SteveH-CO]

There's a short stub on top, welded to the frame. Part of it is chipped away. Agreed that you could drill it all out and run a tube down closer to the blade.

 

[BD1]

There's a short stub on top, welded to the frame. Part of it is chipped away. Agreed that you could drill it all out and run a tube down closer to the blade.

My John Deere 8' blade has A sleeve / pipe that the pin drops in. Never had any issues. A grade bolt would fix but definitely not cheap at that length.

 

[FTG-05]

I would suggest that you add a second hole like in the above picture. The S shaped piece will put the pin in double shear and help prevent bending. OR you could bolt the joint instead of pin it like now. It looks to me that things have bent and opened the gap between the sector and the frame. Bolting it will pull things back into alignment. I'd also guess that things flex a bit under load and that gap opens up more adding to the leverage that bends the pin.

If it were mine I'd bolt things together adding strength to the joint. On my blade it is set up with a second point to pin where you have the trailer ball.

good luck

lg
no neat sig line

Looks just like my Everything Attachments Extreme Duty 8' Grader Blade!

Note the close lockup and double shear pin arrangement:

 

[TheEquineFencer]

At our local Big R store (not Tractor Supply), I found a .75", 6" long tractor pin.

The design of the blade is such that there isn't much gap between the blade frame and the sector on the blade itself, so I'm not sure this is a design issue.
You can see what the blade was doing to my mild steel rod. I have not tested the new pin to see how it holds up.

I'd check your pivot in the middle, it's probably loose and worn. The new pin you bought is hardened and should hold up better. The "chipped" is where it was made for your pin to have a roll pin so you could rotate the pin to stay up when you wanted to rotate the blade, then drop back in place. Grade 8 bolts make decent "pins".

 

[EdT]

Getting the shear planes closer together would certainly help. Whatever you decide to do, keep in mind that IF it is a shear pin and you make it and its mounting "too good' it won't shear, but something else will when you catch the side of a stump with the blade moving the scene of the damage to something more difficult to fix.

 

[TheEquineFencer]

I've never seen a 3pt hitch blade with a "shear" pin....think about it...

 

[Hot Rod Grampa]

Maybe shear pin is the wrong word. Giving the tool a likely failure point in case of excessive pressure in an easily serviced location would be a better choice. Just saying.

 

[gearhead1]

I would say the distance between the shear planes is about 90% of the issue. I’d figure out if it’s worn and fix that, or if it’s by design, I’d add material like a plate to reduce the distance.

 

[SteveH-CO]

Update - I graded the driveway with the new hardened pin - and it bent slightly. I will keep using it, but I may end up modifying the blade, since the problem isn't really the pin itself.

 

[jessesandy]

How about going to a Pick 'n Pull type junkyard and look for a sway bar or torsion bar the diameter you need ?

 

[ChevyEFI]

Thanks - you all have provided lots of excellent suggestions. The current pin is pretty tightly fitted, but the shearing planes are fairly far apart (just the way it's designed), which is why it bends.

Using a bolt and welding nuts on top of the current plate might work, so I'll consider that. Much to think about, here.

Hard to make out . Is there pipe or tube inside where the pin goes in ? Looks like a short stub on top only. If not enlarge and drop pipe inside. That's what I think the problem is.

That is the thought I had, upon reading the first above post.

 

[joe49]

As mentioned you need to make a double shear bracket. A stronger pin is going to result in worse damage.

 

[sanddan]

McMaster Carr, "fatigue proof". 125,000 psi yield. Mild steel is 30,000 psi. The "stress proof" shown above was 55,000 psi.


https://www.mcmaster.com/#6628k33/=1e23q5n

 

[chrismane]

You’ve got to fix it. Or it’s best to change it all and you won’t have to worry about future problems. The steel rods will continue to bend, in my opinion. I’ve had a similar problem when I bought my tractor and added and attachment to make it a snow blower. After a week, it broke. I didn’t keep the guarantee card (silly me), so I’ve decided to look for good ones, first. Luckily, I found some reviews on growgardener.com and bought a new one and I’ve using it for three years now. No regrets at all.