D31P-20 SN# 47699 Steering Clutch/Brake

[just-a-mechanic]

Hey guys I bought a new to me unknown year D31P-20.

I have videos and pictures to attach. But unable to at this moment. I will do so very soon.

questions:

I have a wet clutch/brake system, the manual says it’s supposed to be dry. That’s odd - I have a dipstick into the steering clutches cavity. So definitely wet.

The frame lists this as a D31P-20, not 20A. Anyone know the year of this? 96-97? Maybe?

The components of the clutch and brake assembly appear in pretty good shape. No brake band wear for the braking system and it appears someone recently replaced the brake lining.

my issue: clutch does disengage when trying to turn. This was confirmed. Brake will not apply to allow the machine to turn. Brake actuators extend variably as designed, depending where you position the control. (Pilot controls, manual) The pressure is approx 250/270 psi a bit low but good enough.

What is odd is the brake liner has been checked and it is over .25” of material remaining on the brake band. (Books says wear up to 4.6 mm I think, I Used a precision ground gauge block) The part number listed on the brake liner is -113, not 114 called in the manual. However it looks like it was just superseded.

All components look good. The brake band nut has been adjusted until it bottoms out, it never applies any pressure to the clutch assembly. So the brake band is too loose as it is assembled.

So I can not apply 350inlb of torque against the band, then looses 2.5 turns ti properly set it. As the band is never torqued.

I’ve been cross checking to see if the incorrect parts have been installed into this system. Seems like something is undersized in the wet clutch or oversized in the brake band.

What do you think?

 

[just-a-mechanic]

 

[just-a-mechanic]

 

[just-a-mechanic]

 

[just-a-mechanic]

So the Steering Clutch Brake acts to be too large [left and right sides], as you would expect with worn out Brake Liner/Band. - Both sides, Left and right. Previous owner stated - He knew nothing about mechanics or this dozer, and could tell me nothing [he or someone he paid has been in this dozer, fresh silicone etc..]. Which is fine, but I don't put it past "them" to have done things to just fix the issue, rather right or wrong.

The wear on the Brake Liner appears to be new [someone replaced it, to fix this issue is my guess], both sides, left and right. So now nothing seems to add up. If I replaced the brake band, I will end up with the same issue, the band will not tighten on steering clutch. That is my assumption based on the condition of the band already installed.

Observations:
Brake liner is good - greater than 6mm stated in the Service manual.
Steering Clutch Brake band is correct part number - Parts manual.
No mechanical Failings - None observed
Brake Band Slack adjuster/Nut will bottom out on Rod, without applying force to the Brake Band - Possible wrong part - But both Sides?

Conclusions:
FML

Seriously, this is a head scratch-er for me, well at least from the way I am approaching it. Any takers care to give me their perspective?

I have cut some spacer material, [Steel] approx 3/8 to 1/2 thick to go under the Brake Band Adjusting Nut, this will work for my purpose - and I think without any ill side effects, but I would like to know the "why" this is not correct. I rather this be right than rigged.

The Band is either too big, because wear material is greater than nominal size according to the book, or the Clutch is too small, probably not the issue, but maybe it was replaced on both sides, and there is not visible wear on the clutches.

Another possibility is the "rod" to tighten the band is too long, or the nut is too short, both sides... things seem far fetched.. so i don't know.

Thanks!

Also, to just make me feel better, here is a picture of my Excavator, that just works. No issue now that I have cleaned out the main pressure relief

 

[just-a-mechanic]

Well I put in the two steel spacers to make the brake band come in contact with the clutch assembly.

The brakes and variable and “on a dime turning works fine as expected.

I would like to figure this out, but it won’t be right now. I’ll keep an eye on her and make sure nothing starts to give trouble, but it seems to be ok for now.

Anyone got a year on this dozer from the SN?

 

[southernman13]

I have a 46628 it’s a 96

 

[just-a-mechanic]

I have a 46628 it’s a 96

Thanks for confirming!

What return filter do you use for your hydraulic oil? I ask because all the filters I’ve found are quite expensive.

Also, I’m thinking about running 15w-40 in everything for a bit to flush the system. Right now Walmart has it in pretty decent price point at the moment. What do you run?

 

[southernman13]

I run 15/40 or saw 30. I bought hyd filters from Komatsu only place i found them

 

[just-a-mechanic]

I run 15/40 or saw 30. I bought hyd filters from Komatsu only place i found them

I have multiple cross referencing numbers for the hyd filter I’ll post them if you’d like. The Baldwin states it’s about 65/70$ Online.

Does your Dozer have a straight blade or is it an powered tilt and angle?

I ask because the parts manual I have only shows the straight blade, but the 20A parts manual shows the powered angle blade.

I think for the first oil change I’ll use 15w40 in everything. I’ll decide later on from there.

I found another issue this evening. When I was troubleshooting the powered angle blade hydraulics, I found the short shaft between the engine and transmission was very wobbly. Turns out the bearing was complete gone in the damper assembly, that bolts to the back of the engine.

Glad I caught that or This would have destroyed the transmission input shaft and resulting in more damage.

 

[just-a-mechanic]

https://www.icloud.com/iclouddrive/0f84yZN6Zt7vSikZKbR4nUEhw#D31P-20
This is my cheat sheet for this Dozer, its just a draft but you may find it helpful. Also in the folder is the -20 and -20A parts manual.

Also, here is the video of the short shaft operating. You can see what I was describing!
https://share.icloud.com/photos/027TggQ4vj4C17IAsUO4kFQVw



The dozer I have has the 6 way blade as described above. I would like to find a seal kit for my Dozer Angle and My dozer lift cylinders. I also need new "rubber" bushings. I have a number of grease zerks that need to be replaced and some that are broken out.

So far so good! ha

 

[Welder Dave]

Could the linkage for the brakes have been adjusted for worn out brakes and not adjusted back when new brake bands were installed? Just thinking the linkage could have been adjusted so the the adjusters at the brake bands were at their limit. Maybe the linkage can be adjusted so the brake band adjustment can be backed off so it it will work without the spacers.

 

[southernman13]

Also there’s a little block on top of the transmission that has a shaft running through it. It has a small arm on either side that moves the linkage for the brakes. Make sure it’s getting full stroke. On our D31P that shaft was gummed up and wasn’t able to make full stroke. We tore it apart and cleaned it up. Maybe even put new bearings in it. I don’t remember that part it’s been a while. Anyway that was the cause of my steering issues. We drilled and tapped and out a grease zerk on top of it. Now it can be greased. We have a d41 that I believe needs a new damper on back of engine. I haven’t had a chance to look at it yet. Was that a bad job changing that out in your 31?

 

[just-a-mechanic]

Could the linkage for the brakes have been adjusted for worn out brakes and not adjusted back when new brake bands were installed? Just thinking the linkage could have been adjusted so the the adjusters at the brake bands were at their limit. Maybe the linkage can be adjusted so the brake band adjustment can be backed off so it it will work without the spacers.

Hey Dave!

I understand what you are saying, however the actual closing of the brake band by tightening the "adjustment Nut" would bottom out. So i failed at step one, every time. The only way to get to past step one was to adjust the slack in the band.

In other words the way to start the adjustment procedure so you can do the linkages, is to set the band to .3 mm slack. To do that you tighten the slack adjuster nut to 350in lbs against the clutch. But I was bottomed out on the slack adjusting nut and the band never tightened upon the clutch. So I failed step one. The cover was the only thing installed on the machine, no linkages etc.

 

[just-a-mechanic]

Also there’s a little block on top of the transmission that has a shaft running through it. It has a small arm on either side that moves the linkage for the brakes. Make sure it’s getting full stroke. On our D31P that shaft was gummed up and wasn’t able to make full stroke. We tore it apart and cleaned it up. Maybe even put new bearings in it. I don’t remember that part it’s been a while. Anyway that was the cause of my steering issues. We drilled and tapped and out a grease zerk on top of it. Now it can be greased. We have a d41 that I believe needs a new damper on back of engine. I haven’t had a chance to look at it yet. Was that a bad job changing that out in your 31?

Hey Southerman!

Yeah I seen it, it seems like there are a set of bearings in that shaft as well. But mine were free when I disassembled it. Thanks for the in put however. I have ordered the parts for the damper. Its not a bad job, I don't think. Fairly easy to get to as well. Parts are heavy as they all are, that damper is supposed to be in oil, so if you see a dry sump you know you have a issue. Mine was dry and the bearing gave up the ghost. I should be able to get it back this Saturday if the parts come in.

 

[Welder Dave]

Could the brake band adjuster have been changed and that's why it won't tighten enough?

 

[just-a-mechanic]

Could the brake band adjuster have been changed and that's why it won't tighten enough?

Well what I kinda think is that the clutch and band assembly came from another dozer perhaps, or the "rod" that holds one end static, but it would have to be both sides, and both sides behave the exact same way. Kinda odd - Either way, a 3/8 steel spacer fixed my issues for now, I dont see why it would be an issue mechanically. But we shall keep an eye on it.

 

[just-a-mechanic]

Hey Guys!

So I have been digging into this Dozer, its seems all D31P-20 and series such as this use the same steering brake and clutch plates and frictions. My Shop manual states some are wet style and some are Dry. It appears that doesn't matter to the disc assembly either bathed in oil or not. This doesn't make sense to me? Any takers on that?



Im concerned that I have mismatched parts and if this steering clutch assembly can be in oil or not. It seems these parts were recently replaced, so I don't want this to go out in a few hours after I got everything put back together.

Online Parts manual can be found here:

https://777parts.org/a1/

 

[epirbalex]

So the Steering Clutch Brake acts to be too large [left and right sides], as you would expect with worn out Brake Liner/Band. - Both sides, Left and right. Previous owner stated - He knew nothing about mechanics or this dozer, and could tell me nothing [he or someone he paid has been in this dozer, fresh silicone etc..]. Which is fine, but I don't put it past "them" to have done things to just fix the issue, rather right or wrong.

The wear on the Brake Liner appears to be new [someone replaced it, to fix this issue is my guess], both sides, left and right. So now nothing seems to add up. If I replaced the brake band, I will end up with the same issue, the band will not tighten on steering clutch. That is my assumption based on the condition of the band already installed.

Observations:
Brake liner is good - greater than 6mm stated in the Service manual.
Steering Clutch Brake band is correct part number - Parts manual.
No mechanical Failings - None observed
Brake Band Slack adjuster/Nut will bottom out on Rod, without applying force to the Brake Band - Possible wrong part - But both Sides?

Conclusions:
FML

Seriously, this is a head scratch-er for me, well at least from the way I am approaching it. Any takers care to give me their perspective?

I have cut some spacer material, [Steel] approx 3/8 to 1/2 thick to go under the Brake Band Adjusting Nut, this will work for my purpose - and I think without any ill side effects, but I would like to know the "why" this is not correct. I rather this be right than rigged.

The Band is either too big, because wear material is greater than nominal size according to the book, or the Clutch is too small, probably not the issue, but maybe it was replaced on both sides, and there is not visible wear on the clutches.

Another possibility is the "rod" to tighten the band is too long, or the nut is too short, both sides... things seem far fetched.. so i don't know.

Thanks!

Also, to just make me feel better, here is a picture of my Excavator, that just works. No issue now that I have cleaned out the main pressure relief

View attachment 269349

Has to be wrong brake bands as they are too long . Is there any wear of the fiber at the bottom of the band ? What about the drum being machined down to have a new wear surface because of badly worn bands no being replaced in time

 

[just-a-mechanic]

Has to be wrong brake bands as they are too long . Is there any wear of the fiber at the bottom of the band ? What about the drum being machined down to have a new wear surface because of badly worn bands no being replaced in time

I didn’t notice if it was machined. But I did notice no wear seemed to be on the outer drums. If you look at the pictures above, it seems like someone replaced both of these assemblies.

The steering clutch case area is clean indicating to me it has always been an oil bath, but the manual says it should be dry for every blade dozer -D31P-20 series.

So maybe someone put a blade on a trimming dozer and sold it as a dozer?

My main concern is:

Is there a requirement for different clutch material : brake material when using oil bath or not. The parts manual seems to indicate it can be used either way.

But then why do people change out steering clutches when they get wet with oil?

Perhaps komatsu material is good enough for either oiled or not oiled?

So that’s is my dilemma!