Cat D7 3T Cable Unit Repair

[northriver]

Bought a Cat dozer last year, a 1954 Caterpillar D7, S/N 3T26330. The biggest problem my worthless service manual can't help me with is with the cable unit: the controls will raise the blade, but no brake is in place to keep the blade up.

My current problem started with the former owner (I bought it thinking I would convert it to hydraulic). He reported that the blade couldn't be raised or lowered but that he adjusted it so the blade could be raised; I assume that what he adjusted was the brake. I assume the brake prevents the cable from going backward when the control is in the 'neutral' position, and that pushing the control the other way simply releases the brake, allowing gravity to pull the blade down. Am I correct?

I know nothing about these units and have nothing to go on. Can anyone tell me more about the cable unit, have any schematics or provide me with anything else that might be helpful?

 

[d9gdon]

Your service manual doesn't have it in it because it's in a separate manual for the Cable Control Unit.

I'm guessing that it's a #25 CCU. Here's the operations manual that would tell you what to keep adjusted:

http://www.ebay.com/itm/1947-CAT-Ca...s-25-23-Owners-Manual-ORIGINAL-/372023348716?

They have a separate parts manual too:

http://www.ebay.com/itm/CATERPILLAR...822297?hash=item489fdec5d9:g:hP0AAOSw-9RZb9Yd

On edit: I looked up that part number on the side of the case that I could see in your picture and it is indeed a #25 CCU.

I don't have experience with cable controls but others on here do. Another good site to visit is www.acmoc.org

 

[DPete]

You are correct about how it works. It is difficult to explain the brake adjustment, I suggest you join over at the ACMOC site and search or ask in a thread. The site is all about antique Cat equipment and there is a diagram there that will help. It has to be in time to work correctly, not just a matter of tightening the brake. There is a brake tension spring also. If the drum and brake lining are good and oil free from leaks the adjustment procedure should get it to stay up. If there is oil or grease on the brake you have to solve that .

 

[ol'stonebreaker]

Those units are hard to get dialed in, but once set right you'll love it. One of the mechanics I worked with yrs ago was a master with them. Once he got it set right you could tap the handle and the blade would drop no more than an inch. Dpete is right to go to the mentioned site. I'm sure someone there will help you with it.
IIRC the big square nut in the first pic is the brake adjustment. IIRC you turn it counterclock in small increments to reduce brake pressure. I might be wrong because it's been 40 yrs since I've worked on them.
Mike

 

[Scrub Puller]

Yair. . . and once it is adjusted, it should be operated like a steering clutch, either fully engaged or fully disengaged . . . quick stabs in and out no attempt at easy peasy on a blade . . .more gentle on a scoop (pan) which is pretty much lift or lower and return to hold.

When they are working right they are a joy.

Cheers

 

[Tones]

Gess I used to know how to set those winches up back in the late 60's early 70's but to long away from them to remember. I got a head full of hydraulic crap now.

 

[DMiller]

Judging from picture 3 the friction material may be about done as well as well lubed. This could be a major part of the problem.

 

[bccat]

Bought a Cat dozer last year, a 1954 Caterpillar D7, S/N 3T26330. The biggest problem my worthless service manual can't help me with is with the cable unit: the controls will raise the blade, but no brake is in place to keep the blade up.

My current problem started with the former owner (I bought it thinking I would convert it to hydraulic). He reported that the blade couldn't be raised or lowered but that he adjusted it so the blade could be raised; I assume that what he adjusted was the brake. I assume the brake prevents the cable from going backward when the control is in the 'neutral' position, and that pushing the control the other way simply releases the brake, allowing gravity to pull the blade down. Am I correct?

I know nothing about these units and have nothing to go on. Can anyone tell me more about the cable unit, have any schematics or provide me with anything else that might be helpful?

Cat has separate manuals for cable controls, there,s lots of them on eBay, service manuals are not worthless they are a godsend

 

[northriver]

Thanks for all the quick replies, much appreciated. I'd seen the CCU manuals on JenSales, but didn't know which one to buy; #25 CCU manual on eBay is quite a bit cheaper, I think I'll go that route. Info on these things is hard to find, seems like more of them have been converted to hydraulic than anything else. I'll try to post some info and pictures when I get the manual and whenever I'm able to tear into it.

 

[northriver]

BTW, should I end up replacing any parts (I might just steal some from the second drum), what's going to be the best route for parts?

 

[sled dog]

Those units are hard to get dialed in, but once set right you'll love it. One of the mechanics I worked with yrs ago was a master with them. Once he got it set right you could tap the handle and the blade would drop no more than an inch. Dpete is right to go to the mentioned site. I'm sure someone there will help you with it.
IIRC the big square nut in the first pic is the brake adjustment. IIRC you turn it counterclock in small increments to reduce brake pressure. I might be wrong because it's been 40 yrs since I've worked on them.
Mike

Hey my Friend... The big square nut is the clutchs or discs adjustment. Used to do mine with tractor in neutral and master clutch dogged in, engine at idle. Small, small adjustments and listen to the discs start singing to you. You knew right away if you went too far, the blade would start raising. Ssssiiinngg ssssiiinng ssssiiinnnggg. A sound as sweet as a pony motor on a cool fall morning. Both almost a sound of History now..

 

[ol'stonebreaker]

Thanks, sled dog!! As I said it's been a lot of years since I've worked on one. Your post jogged my memory.
Mike

 

[Scrub Puller]

Yair . . .

A sound as sweet as a pony motor on a cool fall morning.

You done gone and made me cry.
Cheers.

 

[sled dog]

Yair . . .

You done gone and made me cry.
Cheers.

I knew, I just knew, that you, old son, would understand. And you Sir, have made my day ! All the best, man. Chuck

 

[wayne.d7]

The hole with 4F 2518 part no under it have a look in that hole you will see a roller with a grease nipple in the centre of it
When that roller centres up with the centre of the hole the adjustment is correct
To move the roller,the square hole to the left with the lever and the spring showing there are 2 nuts on a 1/2 inch threaded rod that connect the ends of the brake band,back off the lower nut, then wind down the top nut,as you do this observe the roller move towards the hole,when the roller is in alignment with the hole lock up both nuts onto each other
The piece of flat with the spring fixed to it needs bent back so its straight
Inside the top of the square hole you will see another spring about 2" diameter this is the band tensioner, tighten this if the blade won't hold up.
The square shape nut in the centre of the unit is the clutch adjustment, as someone above said, loosen the clamp, then tighten the nut till the clutch plate binds then back it off a little then retighten the clamp.Do this with the engine shut off. Good luck

 

[wayne.d7]

The side used for the blade adjusts in the same way ,you will have to take off the sheave block to get at the brake adjustment. You will need to take the cover off to check that there are some brake linings left,with that off you will be able to see how it all works.With the cover off to adjust the roller to the right position,there is a 1/4 inch hole in the lever the roller runs on,adjust till this lines up with the grease nipple Make adjustments with control lever in neutral position Get the adjustment spot on and the old girl will be cool to operate