I have a very well worn d7f cat of 1970 vintage that I use for a tail hold in our logging operation. The track tensioner on the right-hand track has gone haywire and the track has gone so slack it wants to fall off every time we go to use it. What is the best way and what all would be needed to repair that?
Replaced one on my buddy's 1971 Cat D7F last year . We broke the track first so we could slide the idler forward . Might have been 5 or 6 bolts holding the piston assembly to the track frame . Yanked it off & took it back to the shop to install the seal . Wish I had snapped a few photos of it . Went pretty easy . Just used basic hand tools nothing special . Remember a snap ring in the piston bore . Had a farm tractor with loader to assist with the track .
Most of the D6 and larger standard track dozers are nearly the same. I seem to remember there is a cylinder going back into the track frame and a piston is inside that cylinder and it carries the seals. The piston bears against a knob on the cage for the recoil spring and the cylinder is bolted to the end of the rod that is connected to the front idler bracket. You have to push the front idler all the way to the back and then break the track. I used to break it over the idler an then back the machine up enough that the end of the track was sitting on the frame just in front of the rear top roller. I'm not sure but I think you can then unbolt the cylinder from the idler rod and move the idler till the bracket flange is up against the front top roller stand. You can then bar the cylinder out. It should just clear the front top roller stand. If it doesn't you will have to pull the stand. The piston is inside the cylinder. If the seals are that bad it should just about slide out on its own. I did have problems with the inside of the barrel being bad though. The other issue is if the track is worn out the adjuster is alway at the end of its stroke and it wears out the inside of the barrel there. Good Luck
Good description John . Found some generic photos off the web that look pretty close to it . Second photo is a D4 but shows pulling the assembly out . Remember getting it on the work bench , removing a snap ring and used a brass punch to drive the piston out . Seal kit was around $ 25.00
This is what the various hyd track adjustment look like apart on a 941 loader that we rebuilt a couple of years ago.......would be similar likely, only smaller.
That sure looks allot like it Metalman !
Thanks a bunch guys! I think that the spring broke or something as it was fine then we were moving tailholds & it has been slack as all hell since.
I've seen that once or twice on the older machines that didn't put oil in that area. If you clean out the area at the back of the track frame between the sprocket and the track frame you should be able to see if there is a nut there. If it is there and doesn't move it is safe to take off the flanged cover at the other side. I'm pretty sure you will have to pull the front top roller stand to install a new spring. Usually the old ones come out in pieces if broken.
There are two shoes or stops that hold the pilot assembly back at the front which will hold the spring caged, even if the nut is missing. If he takes the cover off over the spring he should be able to see if the spring is broken. Should be grease leaking out around the adjuster if it is the seal. Maybe a couple pictures would help when he gets into it. Here is a picture of my loader once the new spring was installed.
Thank you guys for all the brain power!
If you PM me your phone # I can tell you a easy way to reseal your adjustor takes about 1 hour. Bob
I bring up the nut because an intact spring has about 30,000 pounds of pressure on it compressed. The stops are probably two 3/4 inch bolts on each stop and the machine is over thirty years old. Not so sure I would trust those stops. I would be very careful taking the bolts loose on the flange and see if it moves out on its own. If so you might want to regroup.
For sure...........the power of that spring is to be revered, absolutely; not to be messed with. On my 941 the specs said the compressed spring force was around 8 tons so I can see a D7 being double that or a little more. The front two shoe brackets have a dowel on each one going into the track frame, which helps keep things secure as well. Often the back nut is seized as that is usually a fine thread on the long rod, or at least on the 941 it was, making hard to get loose. On my 941, both recoil springs had been broken, so I torched the remaining good coils, one at a time until it was relaxed & no more a safety hazard, before removing them.
In my experience the back nut can be gone completely. Then there is nothing to contain the spring when you go to take the front flange cover off. That's the point I was making.
The adjuster cyl. does not even contact the spring so if the spring stops are intact the flange can be taken apart .By the way the spring stops are double doweled and double bolted on each side of the spring . This tractor is closer to 45 years old. Bob
On a D7F the spring is inside the track frame and contained by a flanged cover with six bolts. As I recall the stops you are speaking of go on the machines with an exposed recoil spring. I was not referring to the flange on the track adjuster cylinder when speaking of the spring tension.
No they aren't. Bob
hi i just did my d6e and if your tracks are well worn you can change the seal without breaking the track...just jack the idler all the way forward...undo the 5 bolts on the flange and there is just enuff room to pull the piston forward to expose the seal..take off the snap ring & change the seal..its fiddly but heaps better than breaking a track
Before you go into all that, you sure it's not the fitting that you pump grease into? Try to pump it back up, if grease comes out around it unscrew it and get another. About 75$ from Cat for a new one.