[rockadanny]

This actually is inside a plastic handle that attaches to the crank on my trailer lift.
The bolt sits loosley (so the handle will spin when cranking it) inside this plastic handle and sticks out the bottom, were it not broken would be a nut at the bottom to attach to the hand crank:





The bolt as shown is 3" long (so unbroken would be longer), thickest part is 1/2" wide, bottom part which fits into hole to attach to crank is 3/8 " wide.

Not found at trailer store, hardware store, or Lowes/Home Depot. Not sure where to get this heavy duty type of bolt. Do you know?

[Jack the cat]

Shoulder bolt?

https://duckduckgo.com/?q=shoulder+bolt&t=newext&atb=v1-1&iax=images&ia=images

[aldcoll]

I had the same issue a while back and had to make up one.  I added some tubing over a bolt long enough with the correct thread and a washer or two.  Its was that or a new jack. 

Here is 1 that is close at $112.00. Well it is Stainless.
https://www.fastenal.com/product/fasteners/sockets/socket-shoulder-bolts/602314?categoryId=602314&level=3&query=Shoulder&isExpanded=true&Finish=Plain&productFamilyId=30220

How about a pic of the linkage this will attach to?

Alan

[Peter J]

Maybe this?

https://www.etrailer.com/Accessories-and-Parts/etrailer/MJ-1000B-KB.html?feed=npn&utm_source=google&utm_medium=cpc&utm_campaign=Google%20%7C%20Smart%20Shopping%20-%20Accessories%20and%20Parts%20-%20Maximize%20Revenue&adgroupid=78445819423&campaignid=6893256689&creative=395353250592&device=c&devicemodel=&feeditemid=&keyword=&loc_interest_ms=&loc_physical_ms=9029599&matchtype=&network=u&placement=&position=&gclid=Cj0KCQjw8vqGBhC_ARIsADMSd1BDUh3BnplgKPCRfIDeoC6Ld2CJ6VUjtxYg5my8EqnuD4fcmdqBJbYaAiOvEALw_wcB

What size is threaded part?

[Bob2]

McMaster Carr  https://www.mcmaster.com/shoulder-bolts/

Yes Nut and washer..

[rockadanny]

Thank you all for your help. I will pursue these options.
Unfortunately the trailer is at the barn so unable at this time to post the jack crank arm this attaches to. It is a typical kind of crank, nothing special. Looks something like this:

[Big Red Machine]

I'd put a bolt in of proper thread, a couple of nuts to secure it, and cover it with a piece of PVC and large fender washers myself.

[Bob2]

.

[Rusty Jefferson]

Here's what Grainger has in 3-1/4" and 3-1/2" length x 1/2" diameter x 3/8"-16 threads

https://www.grainger.com/category/fasteners/socket-screws-and-set-screws/shoulder-screws?attrs=Shoulder+Length%7C3+1%2F2+in%7C3+1%2F4+in~~Thread+Size%7C3%2F8-16&filters=attrs

Are the bolt threads broken off in the crank arm?

[Bob2]

https://www.amazon.com/dp/B07L5MDFVX/ref=sspa_dk_detail_4?psc=1&pd_rd_i=B07L5MDFVX&pd_rd_w=gPHnl&pf_rd_p=80360d1c-2d74-4d2e-9034-f92fb5248b33&pd_rd_wg=5wI07&pf_rd_r=FZ13VFRVK2BBXA10WKFV&pd_rd_r=15d1a565-4cb7-4ccd-aa85-f67071fa18c5&smid=A1THAZDOWP300U&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyU0ZFR0dCOUhDTURQJmVuY3J5cHRlZElkPUEwNTE4ODk3MzRCR1RXWEg1TlBLUSZlbmNyeXB0ZWRBZElkPUEwNTI3NjA3MU9QS1c1N0ZJSFRMRyZ3aWRnZXROYW1lPXNwX2RldGFpbCZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

[rockadanny]

Hmm ... interesting. Only 2.5", but might work. Thanks @Bob2!

[jules]

If the arm is wide enough I'd be tempted to drill the hole out and tap it to take a 1/2", preferably stainless steel, bolt. Use a nut on the topside screwed up tight to the end of the thread and a nyloc on the bottom, preferably with Loktite. Would cost maybe $10 a lot less than the $112 mentioned above [even for stainless that is way to high]. Handle? A nice length of garden hose  .

The existing 3/8" just looks a bit too thin, even if rust was a factor.

Is it possible to grease the thread of the shaft that winds the thing up and down? Could make it work better.
 

[Bob2]

If the trailer jack is old and not working properly maybe it's time to replace it.... Hopefully the original wasn't welded in place..

https://www.amazon.com/RTK-Technologies-Frame-Trailer-Jack/dp/B093NWD2F9/ref=sr_1_1_sspa?dchild=1&keywords=trailer+jack&qid=1625997561&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExQ1JDNDNCOFBPWDROJmVuY3J5cHRlZElkPUEwMjc5MzkzR1pTWlA5QklaMFYxJmVuY3J5cHRlZEFkSWQ9QTA1OTExNTJHTkwwSE84VDZJOFYmd2lkZ2V0TmFtZT1zcF9hdGYmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl

[Bob2]

Ok, getting crazy....... Amazon says you need this?




https://www.amazon.com/CURT-28921-Replacement-Frame-Handle/dp/B004QEH1US/ref=im_2/137-7349101-6066002?pd_rd_w=zj4ND&pf_rd_p=3558f5bd-f1fb-47ce-82d2-93422551dcc6&pf_rd_r=FHS8XT6458KXFVYC2EZZ&pd_rd_r=53ebada5-7218-4343-a18c-14059d6b893c&pd_rd_wg=sPLNR&pd_rd_i=B004QEH1US&psc=1