What grade of steel is used on Fork Shafts?

[joestewart]

I need to replace the fork shaft on my 644. Its 1-3/4 inch diameter and 54 inches in length. Made some calls to the usual telehandler parts houses, and gentlemen it seems that some of them are just having their local steel yards cut some round stock to length, and then reselling this to the customer. If this is the case, I can just buy a length of round stock here at home, and save the $65 freight in addition to the usual mark up. Called the local steel yards, and they want to know what grade steel is used for this particular application. Not sure what the answer is. All I know is that it is made from "high carbon steel." Does anyone know what specific grade of steel is used for telehandler fork shafts?

 

[TOM V]

4140 is a good tough material. would cost you about $200 for that size stock.

 

[Speedpup]

I paid 195 or even less for my 1044B and no where near 65 for shipping. It was may be 20 bucks. It has the chamfered ends and the holes drilled so that is more work to do. Plus I know what I got. I know it was below 200 and I was fairly shocked from Lull JLG about 4 months ago.

 

[bobb]

it could be cold rolled steel. if you have an automatic center punch you may be able to eyeball it. punch a spot on your shaft and then try it on a piece of cold rolled at the steel supply house. the depth of the dents will tell you which one is harder. the ones i have seen seem to bend quite a bit. if you press them out they dont crack. i know it isint as good as new but they dont crack when pressed out so it makes me think there is not much carbon in there. i just priced one for a gradall and it was like $220 to my door. i think im gonna buy a pair.

 

[joestewart]

OK, thanks gentlemen. I called twelve vendors and I finally settled on an OEM shaft (I bought from Lull/JLG).

During my research, I got a variety of prices ($189-$272 delivered or local pick up).

The vendors don't necessarily inform you that they are selling you an aftermarket shaft, so if you are thinking about buying a fork shaft, inquire BEFORE YOU BUY. Most of the vendors that are selling aftermarket shafts did not know the grade of steel used in the shaft they were selling. The usual answer was "its the steel we always use." I find this scary. Could this be the reason that my old shaft was bent? One of them did the research for me: that vendor uses "C1018 cold rolled steel."

themetalmerchant on the online auction was asking $75.18 for 4140 steel, 1-3/4 x 54 inches, plus ups shipping. Very tempted to go this route, but for such an important application, better senses prevailed.

Thank you for your input.

 

[icestationzebra]

Obviously 4140 is stronger, but you also have to consider the accuracy of the OD and corrosion resistance on the ability to slide the folks. Cold rolled typically comes in very close to spec'd OD. I'm not sure about the difference in corrosion, but the OEM can always use a coating. The other advantage of using a relatively soft shaft is that the shaft will wear instead of the forks or carriage.

ISZ

 

[oceanobob]

We run an 8042 Terex square shooter (w/o the feature) which is a pretty beefy machine. The fork shaft has a little bend which makes the fork want to go to a certain spot (hang there) and a little monkey to remove to change the forks. We want to make some sleeves that clamp around the shaft to keep the forks in one spot considering side to side so we can side load materials and pallets and stuff and not reposition after bouncing around.
I inquired and was (also) informed fork shafts for these machines and TLB kits are simply cold finished 1018 or sim. This would provide a hardness in the B scale and would be fairly easy to drill holes in the ends for the lockrings.
A 41xx series or a 43xx series, if one bought that quenched and tempered (Q & T) would be some stout material, well into the C scale which would make machining/drilling a bit of a chore. An often used idea in industry is to specify normalized condition of the above materials which means no special heat treating - but the material is more stout than the cold rolled and has good energy absorption behavior and is machinable - one orders an alloy and maybe in one school of thought they didn't take it to the end process by doing the Q&T but having the alloy in the normalized condition is definitely a step toward strength.
Myself, in view of all the above, would get the cold finished mild carbon steel material as this is clearly a notch above hot rolled and the shape and finish of the HR material is not on par with the cold finish.
Corrosion resistance of the 4xxx material is a bit better than the cold rolled steel, but still is susceptible to general corrosion (eg rusting).
The improved hardness depth of the cold finished material is not typically that much and not nearly as say surface hardening. Especially compared to the 4xxx which has wonderful through hardness characteristics.
Unfortunately there is no easy way to sort by determining the chemistry of the 4xxx series over the carbon steel; having said that the spark test can show the carbon is up around 30 or maybe 40 for the 4xxx but the carbon steel can be procured just as easily in 1035 or 1040 too, so this characteristic doesn't help separate. The chem spot check kits don't have the discernment at the levels of the alloy in the 4xxx to separate it from carbon steels - sorry.
A coupon sent to a metals lab for a optical emission spec is the about the only way to be sure.
The hardness test can be a good one though, as the B and C scales overlap just a bit and the hardness can be directly correlated to the strength.