EH DC-3 I NEVER!!!

Klyde

Member
Location
Upstate NY
Buddy was pulling Saturday night at local show, something snapped and he stopped. I figured a broken chain but not this. One broken and 2 more fractured. Chain does not have more than an 1/8" of wear. If you go by the other chain only an 1/2 to 3/4 inch of play. Hmmmm

Last is cause I got sick of all the JD & IH slug hole fillers, so I made my own.
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never heard of o breaking either but it is highly possible ,,.what weight were you guys pulling and how often ?/
 
He was in the 6500. I don't think there was anything crazy with the motor either. Now I wonder about mine...
 
I would bet it was damaged long before it started being pulled,,, looks like a shock load to me caused the fracture,, a dead pull would pull the chain more rather than fracture one or two links, Love the hitch cover,, I hope you have a bolt holding it on though,,, someone may "like" it too well lol
cnt
cnt
 
(quoted from post at 21:40:26 08/04/16) Buddy was pulling Saturday night at local show, something snapped and he stopped. I figured a broken chain but not this. One broken and 2 more fractured. Chain does not have more than an 1/8" of wear. If you go by the other chain only an 1/2 to 3/4 inch of play. Hmmmm

Last is cause I got sick of all the JD & IH slug hole fillers, so I made my own.
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That Looks like a typical fatigue fracture. The tractors over 60 years old. Fatigue happens at typical loads cycles but is more prevalent and at times catastrophic in overload conditions. An inspection of the entire chain or both chains is essential if you intend to reuse it. I know this is long but it should give you some insight.


Fatigue Properties
Fatigue cracking is one of the primary damage mechanisms of structural components. Fatigue cracking results from cyclic stresses that are below the ultimate tensile stress, or even the yield stress of the material. The name “fatigue” is based on the concept that a material becomes “tired” and fails at a stress level below the nominal strength of the material. The facts that the original bulk design strengths are not exceeded and the only warning sign of an impending fracture is an often hard to see crack, makes fatigue damage especially dangerous.
The fatigue life of a component can be expressed as the number of loading cycles required to initiate a fatigue crack and to propagate the crack to critical size. Therefore, it can be said that fatigue failure occurs in three stages – crack initiation; slow, stable crack growth; and rapid fracture.
As discussed previously, dislocations play a major role in the fatigue crack initiation phase. In the first stage, dislocations accumulate near surface stress concentrations and form structures called persistent slip bands (PSB) after a large number of loading cycles.  PSBs are areas that rise above (extrusion) or fall below (intrusion) the surface of the component due to movement of material along slip planes. This leaves tiny steps in the surface that serve as stress risers where tiny cracks can initiate. These tiny crack (called microcracks) nucleate along planes of high shear stress which is often 45o to the loading direction.
In the second stage of fatigue, some of the tiny microcracks join together and begin to propagate through the material in a direction that is perpendicular to the maximum tensile stress. Eventually, the growth of one or a few crack of the larger cracks will dominate over the rest of the cracks. With continued cyclic loading, the growth of the dominate crack or cracks will continue until the remaining uncracked section of the component can no longer support the load. At this point, the fracture toughness is exceeded and the remaining cross-section of the material experiences rapid fracture. This rapid overload fracture is the third stage of fatigue failure.
Factors Affecting Fatigue Life
In order for fatigue cracks to initiate, three basic factors are necessary. First, the loading pattern must contain minimum and maximum peak values with large enough variation or fluctuation. The peak values may be in tension or compression and may change over time but the reverse loading cycle must be sufficiently great for fatigue crack initiation. Secondly, the peak stress levels must be of sufficiently high value. If the peak stresses are too low, no crack initiation will occur. Thirdly, the material must experience a sufficiently large number of cycles of the applied stress. The number of cycles required to initiate and grow a crack is largely dependant on the first to factors.
In addition to these three basic factors, there are a host of other variables, such as stress concentration, corrosion, temperature, overload, metallurgical structure, and residual stresses which can affect the propensity for fatigue. Since fatigue cracks generally initiate at a surface, the surface condition of the component being loaded will have an effect on its fatigue life. Surface roughness is important because it is directly related to the level and number of stress concentrations on the surface. The higher the stress concentration the more likely a crack is to nucleate. Smooth surfaces increase the time to nucleation. Notches, scratches, and other stress risers decrease fatigue life. Surface residual stress will also have a significant effect on fatigue life. Compressive residual stresses from machining, cold working, heat treating will oppose a tensile load and thus lower the amplitude of cyclic loading

The figure shows several types of loading that could initiate a fatigue crack. The upper left figure shows sinusoidal loading going from a tensile stress to a compressive stress. For this type of stress cycle the maximum and minimum stresses are equal. Tensile stress is considered positive, and compressive stress is negative. The figure in the upper right shows sinusoidal loading with the minimum and maximum stresses both in the tensile realm. Cyclic compression loading can also cause fatigue. The lower figure shows variable-amplitude loading, which might be experienced by a bridge or airplane wing or any other component that experiences changing loading patterns. In variable-amplitude loading, only those cycles exceeding some peak threshold will contribute to fatigue cracking.

Best of luck with it Byron
 
Was pulling a LA and the chain broke or so I thought. Sold the tractor and the guy said the link came out.No damage done,sure made a bang and quick stop.
caseman-d
 

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