Drawbar Rebuild

[carpetfarmer]

What would be the best way to rebuild a well used drawbar?

I'm thinking cut a short length of heavy wall pipe for a sleeve, then start filling in the gap around the pipe with some harder welding rod. Or would it be just as well to completely weld the hole shut and drill a new one? Are there any other techniques?

 

[jon f mn]

I always just fill them in then drill or torch a hole. The pipe use a don't sound too good to me as pipe are soft.

 

[oldproudvet]

I'm not a welder, but I've seen the carbon (or some non weldable material) rod or plug you set in the hole, weld around it with proper rod and then remove it, leaving a neat hole. I'm sure any welding shop would know of what I speak. Something to look into anyway

 

[ss55]

I would think a pipe sleeve would be much softer steel than the original drawbar material, so the repair sleeve would wear very fast, but you could check the hardness of each before you start. A headless press fit drill bushing or a liner bushing might be a better repair sleeve because they would be 52100 steel hardened to R/C 62-64. Check McMaster-Carr, Grainger, or Fastenal for a price of stock size drill bushings.

Some drawbars are pretty hard, do you have drills that will cut your drawbar or will you need to use a grinder on it? If your tractor was a popular model, I would check the cost of a used drawbar before starting a repair on the old one.

 

[Case Nutty 1660]

I use a old bearing center the right size on the really worn ones, then weld up the wallered side

 

[jon f mn]

It's called a carbon rod. They work ok, but you will need to grind around the hole so you can get in beside them to weld. It is a good solution for very worn holes.

 

[IA Roy]

Hardened drill bushing hardness would probably get messed up with the heat of welding. Would probably have to do a heat treat procedure to get it hard, and then anneal it somewhat to keep from being brittle. The carbon rod plug makes sense to me.

 

[carpetfarmer]

That's all good info to consider. Thank you.

 

[ss55]

I was thinking either a heavy press fit or use a Loctite style bonding agent like those used to assemble four post die sets. No welding or at most a small tack weld as extra insurance. When I think about it, you are right because most farm shops could not hold the tolerances required for a press fit or a close slip fit.

 

[Jim McVay]

I,d weld it up with 7018 1/8"past where you want it to be and then grind flat and die grind with carbide cutter hole back to where you want it. I also use a welding rod called "super missle weld" to repair and patch and splice drawbar together.

 

[Ron Sa]

The main reason drawbars have hardness is to resist bending. Drawbar pins are also hard for the same reason.

Unfortunately, similar metals with the same hardness tend to gall each other when rubbing against each other under load without lubrication. Galling chews off tiny bits of metal. Galling is the main reason for the drawbar hole to elongate over time.

Hard steel rubbing against soft steel tends to only slightly smear the soft material and not grind it away like galling does. Thus the wear rate is much slower compared to galling. This means that soft weld filler and a hard pin wear slowly because they tend to not gall.

Case Nutty has a good idea. The bearing race is very hard and drawbar pins are medium hard. This is apt to cause slight smearing of the pin but pins are easy to replace. I would suggest welding the race in small increments and allow cooling between weld increments. This will keep the race harder than the average drawbar pin and decrease galling of the pin.