420c safety blocks

General help and support for your Lindeman through 2010 John Deere crawler
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ggfossen
440 crawler
440 crawler
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420c safety blocks

Post by ggfossen » Mon May 09, 2005 5:58 pm

The book says the track assembly on my '56 420c moves back, and pushes the safety blocks into contact with the drive sprockets when too much mud builds up in the track. I don't understand how that's possible because the track assembly appears to be hard mounted to the tractor. Could someone please explain? It must happen because one of my safety blocks is worn completely through.

Thanks,

Gary

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Lavoy
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Post by Lavoy » Mon May 09, 2005 8:13 pm

Look at the crossbar between the trackframes, and where the main sideframes clamp to them. There are rubber pads in between the clamps and the crossbar. Under an extreme load condition, or tracks too tight due to mud or snow, the rubber is supposed to compress and the sprocket will wedge against the trackstop and stall the engine or slip the clutch/clutches.
Track stop wear occors when the bearings go out of the final, and people figure it is just fine to let the sprocket grind against the track stop, hell must be what it is there for.
Lavoy

ggfossen
440 crawler
440 crawler
Posts: 216
Joined: Thu May 05, 2005 8:08 pm
Location: Jacksonville, Oregon

Post by ggfossen » Mon May 09, 2005 9:16 pm

Lavoy,

I saw the rubber pads, but it didn't seem that they would give enough. One more mystery out of the way, but now it looks like I probably will need bearings in the finals. Guess I'll have to go in a bit deeper. Do you have those available, and how much? If the bearings are shot, would I be able to move the sprockets with the tracks off?

'56 420c 5 roller.

Next question: I was just out messing with it after supper. When the right steer lever is pulled full to the read, there is an audible snap just before it reaches full rear, and I can see what I think is the throw out bearing popping back a bit. Lights not too good, but that's the way it looks. Would it be something like linkage going past center? It always returns, and repeats.

Also, are the bearings for the finals in the crawlers anything like the bearings in the wheel tractors?

Thanks,

Gary

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Lavoy
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Post by Lavoy » Tue May 10, 2005 9:15 am

Final drive bearing kits run $160/side for all bearings and seals, $190 with a sleeve to repair the seal groove on pinion shaft. I have at least 2 kits on hand.
The steering lever is coming back too far, and the three balls are popping up out of their seats. Something is way out of adjustment. Clutch should begin actuating when the tip of the lever is about 1 5/8" from the dash.
Lavoy

ggfossen
440 crawler
440 crawler
Posts: 216
Joined: Thu May 05, 2005 8:08 pm
Location: Jacksonville, Oregon

Post by ggfossen » Tue May 10, 2005 10:18 am

Lavoy,

I sort of expected that with the steering lever. I think I'm going to have to get a lot farther into the finals than I had planned. If I do that, I should be able to eyeball the clutches and brakes. Also, I've ordered a service manual, and that should help me. This will take awhile. I have more irons in the fire, and, if I have to get that far into it, I'm going to want to paint everything before I put it back together. Might take quite a bit of awhile.

I do sincerely appreciate your input, though, and if I don't get back to you soon, it's not because I've forgotten about the forum. I will be plodding along.

I had to build a small cover for the tractor, and I built over where the tractor now sets. I'm just finishing that up, and I don't have gravel under it, so it's a bit sloggy with all the rain we've had. I need some dry, and warmer, weather to really get with the program.

Thanks,

Gary

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