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Final Drive Motor on One Side Bogging Down Engine - Cat 304cr

Nige

Senior Member
Joined
Jun 22, 2011
Messages
28,984
Location
G..G..G..Granville.........!! Fetch your cloth.
You mentioned that "I removed the spool. It was a tight fit, but I’d say it was smooth. I didn’t have to fight with it to get it out"
On a machine the size of yours IMO the spool should literally be able to be pushed out of the tunnel in the valve body with no more than finger pressure. It does not sound like yours was that loose.?
When you can try posting some good-quality photos of the spool.
 

uffex

Senior Member
Joined
Jan 23, 2012
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4,464
Location
Lincoln UK
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Good day
The spool is of a hard steel billet whilst the slice is of a softer cast material, a small scratch on the spool can as a rule of thumb be ignored whilst a damaged slice will result in problems. Look hard at the main filters could give you some clue to what may have been going on. Spools of this type will only shift a small distance less than i/2" see attached.
Kind regards
Uffex
 

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  • H2 Diagnose main valve fault.pdf
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Howey Matt

Well-Known Member
Joined
Dec 19, 2021
Messages
128
Location
Howey in the Hills, FL
You mentioned that "I removed the spool. It was a tight fit, but I’d say it was smooth. I didn’t have to fight with it to get it out"
On a machine the size of yours IMO the spool should literally be able to be pushed out of the tunnel in the valve body with no more than finger pressure. It does not sound like yours was that loose.?
When you can try posting some good-quality photos of the spool.

Now that it’s clean and dry, it does push through with one finger. It stays in just enough to not fall out when I turn the slice sideways. It falls out when I shake it.

It came out fairly easily as well - I just had to twist it a bit. I’m wondering if there was some debris in there that got washed out when the fluid came out.

I don’t see any issues with the spool or the slice. No damage, not even a little as far as I can tell.
 

uffex

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Good day
According to the shematicc you have two main pumps No.1 & No.2
Number one provides fluid & pressure for right side crawler - Arm & Option.
Pump number two provides fluid & pressure for left side crawler - Boom & Bucket.
From a distance Im asking do those remaining circuits for the troublesome side perform correctly?
From your post and the photo's I cannot see so much wrong with the spool & slice.

Kind regards
Uffex
 

Howey Matt

Well-Known Member
Joined
Dec 19, 2021
Messages
128
Location
Howey in the Hills, FL
Good day
According to the shematicc you have two main pumps No.1 & No.2
Number one provides fluid & pressure for right side crawler - Arm & Option.
Pump number two provides fluid & pressure for left side crawler - Boom & Bucket.
From a distance Im asking do those remaining circuits for the troublesome side perform correctly?
From your post and the photo's I cannot see so much wrong with the spool & slice.

Kind regards
Uffex

Everything else is working correctly. Boom, bucket, blade, stick, etc. I haven't tested the aux hydraulics because I don't have a thumb yet.
 

uffex

Senior Member
Joined
Jan 23, 2012
Messages
4,464
Location
Lincoln UK
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Good day
The symptoms are very strange, I suggest you measure the return line pressure when the motor is active. Your post describes a loading of the hydraulics when the motor is running, as I have interpreted the issue it is a question of loading and lack of speed.
Question has the spool been removed from the slice installed the wrong way around ?
Kind regards
Uffex
 

Howey Matt

Well-Known Member
Joined
Dec 19, 2021
Messages
128
Location
Howey in the Hills, FL
Good day
The symptoms are very strange, I suggest you measure the return line pressure when the motor is active. Your post describes a loading of the hydraulics when the motor is running, as I have interpreted the issue it is a question of loading and lack of speed.
Question has the spool been removed from the slice installed the wrong way around ?
Kind regards
Uffex

See attached photo. I’m fairly certain it came out like this, which looks correct according to the diagrams I can find. I could be mistaken about how it came out, but I think I remember the ring around the end as I pulled it out.

I’m going to pull the slices around this slice (one of them is the LH travel) and get everything cleaned up and reinstalled correctly. I’m hoping that fixes it.
 

Attachments

  • 184ECCC4-BA05-4E5E-AB1C-875AECD0FA9C.jpeg
    184ECCC4-BA05-4E5E-AB1C-875AECD0FA9C.jpeg
    1.7 MB · Views: 13

Howey Matt

Well-Known Member
Joined
Dec 19, 2021
Messages
128
Location
Howey in the Hills, FL
UPDATE

I got everything put back together and PROBLEM SOLVED! :)

The only problem then was a pretty good leak between the slices. So, I removed the entire main control valve this time, and I'm going to replace the 11 o-rings between the slices. Should have done it the first time around! It's only time and busted knuckles...

Thanks for everyone's help! I really appreciate it.
 

Howey Matt

Well-Known Member
Joined
Dec 19, 2021
Messages
128
Location
Howey in the Hills, FL
Does anyone know how to get the air out of the hydraulic system after a job like this?

My controls are spongy and the machine has very little power. I’ve worked the controls back and forth for a while now, and I unscrewed the plug on top of the main pump to let the air out per the service manual. Nothing seems to be working. The blade is so weak it won’t even pick the machine up. Any ideas?
 
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