Identifying Master Pin vs. Master Link

[Tommy]

Komatsu D37 Identifying Master Pin vs. Master Link

I have a Komatsu D37 that does not appear to have a master link on the track. The parts manual shows some tracks to have a master pin rather than a master link. The manual's illustration of the master pin is very small and without detail. On the machine itself, I can't really see any visual difference in the pins on the track. I need to remove the track to replace the seal on the track adjuster. What do I do?

 

[darinray]

I've had to take a flashlight to look down every link to find the master bushing because I couldn't tell what pin was the master. Basically you have to look inbetween where the bushing goes through the links from TOP side looking down on pads. The master bushing is shorter and doesn't go into the next links ears due to being able to lift the link out when the pins been taken out. The normal links won't come apart like this when you drive the pin out because the bushing connects them as well kinda. Hope this makes as much sense as possible.

Darin

 

[QuickTrax]

The master pin should have some kind of identification on it. It should have a dimple or something to differentiate itself from the rest of the pins. If you have to look between the links to find the master bushing, it is better to do this back by the sprocket because when the tracks are going around the sprocket the pads will not be in the way.

 

[DPete]

Cat master pins had a countersink drilled in one end, don't know about Komatsu, good point about checking between the links. Have not delt with a master pin for 25 years but we used to cut a deep X in the ends out to the boss with a cutting torch to relieve the press fit, then get the hammer.

 

[John C.]

Komatsu also uses the deep dimple in the end of the pin. Problem is they only put the dimple in one end and many times the person installing the pin puts it in dimple first. This puts the dimple end under the machine making it a real pain to find.

Looking at the split between the rails is a good idea but the dozer tracks usually don't spread enough to be able to see the bushing.

Tommy, you didn't mention if your machine has rock guards.

 

[Dr Komatsu]

A genuine Komatsu master pin will have a recessed dimple on both sides of the pin . Also the master bush will be the same width as the end that completes the join, regular bushes are wider than master bushes ,if you can't find a dimple in the pin you could slide something thin to slide in between the links and fell the depth it goes in, a regular bushwill stop you touching the pin , a master bush will let you touch the pin.

 

[jullah2009]

i am also having the same doubt

 

[Trakwork]

Graphic of Master pin...

 

[Tommy]

Thanks for all the great input. I've identified and verified the pin with all of your help. Let you know how it "comes out".

 

[dirtman55]

On the subject of master links,we have a reoccurring problem with the bolts breaking in the threaded part of the link.Three times on new rails & pads in 900 hr. This is on a Komatsu D41E-6 dozer. We have welded the head of bolts to pad so its not a problem of loosening up. My dealer & their product suport man are not of any help. Anybody else had this problem.

 

[QuickTrax]

Make sure all of the paint is removed from where the master links connect. Make sure you don't have any burrs or anything preventing the teeth from seating correctly. Anytime chains are installed, we recommend customers to recheck the master link bolts after running the machine for a few hours.

 

[John C.]

Who made the links? Did the bolts come with the tracks? How did you install the bolts and torque them down?

Bolt failures come down to only a few causes. Improper use, wrong size or grade of bolt for the job, wrong type of materials for the use, poor quality bolts, incorrect installation practices. Installation practices include not cleaning threads, not lubricating threads with the manufactures specified type of lubricants, not making sure blind holes are clean to prevent bolts from bottoming out and so on. I have seen poor designs cause a lot of failures but it doesn't sound like that is what is happening here.

Good Luck!

 

[dirtman55]

The links are OEM Komatsu & bolts . All paint was off & cleaned & tighten to spec. When you thread a new bolt into the new link the fit is loose where bolt will wiggle in the
threads. All the bolts break at the same place, where the threaded part ends.
Frustrated!

 

[Trakwork]

Could be as simple as grade of bolts? Maybe you could get a tougher bolt?


http://dodgeram.org/tech/specs/bolts/SAE_bolt_strength.html


Standard SAE Bolt Dimensions and Grades

Bolt Safe Working Loads (lbs)
(Safe tensile load at 6,000 psi load)
(Safe shear strength at 7500 psi load)



BoltDia(in)
NF Thread Grade 2 Iron Bolt
Shear
(at thread root) Shear
(Full Bolt) Tensile
(at thread root)
1/4 200 370 160
5/16 340 575 270
3/8 510 830 410
7/16 700 1130 560
1/2 940 1470 760
9/16
5/8 1510 2300 1210
3/4 2260 3310 1810
7/8 3140 4510 2520
1 4130 5890 3300
1 1/8 5200 7450 4160
1 1/4 6670 9200 5350
1 3/8 7900 11130 6340
1 1/2 9700 13250 7700
1 5/8 11360 15550 9090
1 3/4 13080 18000 10470
1 7/8 15370 20700 12300
2 17250 23560 13800

Bolt Tensile Strength (Breaking Strength -lbs)
BoltDia(in) Grade 2 Grade 5 Grade 8
Coarse Fine Coarse Fine Coarse Fine
1/4 2350 2700 3800 4350 4750 5450
5/16 3900 4300 6300 6950 7850 8700
3/8
7/16 7850 8800 12800 14400 15900 17800
1/2 10500 11800 17000 19200 21300 24000
9/16 13500 15000 21800 24400 27300 30400
5/8 16700 18900 27100 30700 33900 38400
3/4 24700 27600 40100 44800 50100 56000

 

[dirtman55]

Hey, good question for the Komatsu product support guy. What grade is their bolts?

 

[AirBornOne]

When you thread a new bolt into the new link the fit is loose where bolt will wiggle in the
threads. All the bolts break at the same place, where the threaded part ends.

dirtman55,
Sounds like you've just nailed it.That little bit of motion can be enough to snap a hardened bolt.
I'm guessing an out of spec part or material.
Wrong % of thread engagement,either in the bolt specification or the mating part.
Maybe wrong heat treatment per bolt material or a miscalc of shrinkage.
Either way,I can't imagine a bolt being allowed to 'wiggle' in this application,regardless of how little I know of steel tracks.
Skies.
Jay.

 

[Tommy]

Finally got back to working on my machine. Found the master pin and got it out. Every pin on this machine has dimples. Was able to identify it by looking at the bushing lengths.
Turns out there is some pitting on the shaft coming out of the track adjuster cylinder (see photo). Should I do nothing, smooth it off, replace it or what? Also found the seal on the final drive leaking on the left sprocket. Is it difficult to repair?

Thanks for any input.
Tommy

 

[MrKomatsu]

true komatsu pins have ONLY 1 dimple...............not two......there r many copy cats parts out there....:usa

 

[John C.]

I'm sure Edward is correct on them not being Komatsu chains. As I recall, Komatsu always had split links on those machines from the factory. It looks like your track has strutted links and I don't recall your vintage of tractor having struts. There should be some markings on the side of the links just below where the pads bolt to the link. I'm thinking it will say Berco.

I have never had to repair the sprocket shaft seal on your size and vintage of tractor. I would guess that you have to pull the final and tear it down from the gear side to the sprocket seal.

Good Luck!

 

[bobcatmechanic]

general rule of thumb is if its pitted replace it that being said its all up to you. what does your cash look like for parts. can you afford it if not clean it up best you can and hope for the best. it may last 10 min it may last 10 years so its up to you. personally i would replace it with a new one. recroming is also an option dont know the cost or how well it will adhere and someone on the forum will be able to tell you better on that subject of recroming.