320 BL swing problem

[Big Iron]

the swing on my 320BL Cat has a problem! While working it last week I swung the machine to the left and came up hard against something, swinging the machine to the right about 1/2 way around it came up hard again. I can swing very slowly and the machine will swing 360 degrees, however trying to swing normally it will lock up at various spots. When it comes up hard if you swing in the opposite direction it will go aways (sometimes 90 sometimes up to 180 sometimes 360) and come up hard again. I have never been into a Cat swing assembly and thought someone here might have some drawings or experience with these machines. Your thoughts.
thanks

 

[ben46a]

Well thats never good, I would be pulling the little steel cover below the boom base and have a look see while someone slowly swings the machine to see if there is something jamming it up, or, you could also pull the swing motor for a better look inside the swing gear and bearing. Its pretty much a sure thing the swing motor would have to come out to repair either the motor itself or the swing gear and bearing group. I have a feeling there is a tooth off of either the pinion or thegear group which is why it is locking up. Swinging slowly, the greas can push the pieces out of the way before they lock up.

 

[RKO]

Swing problem

the swing on my 320BL Cat has a problem! While working it last week I swung the machine to the left and came up hard against something, swinging the machine to the right about 1/2 way around it came up hard again. I can swing very slowly and the machine will swing 360 degrees, however trying to swing normally it will lock up at various spots. When it comes up hard if you swing in the opposite direction it will go aways (sometimes 90 sometimes up to 180 sometimes 360) and come up hard again. I have never been into a Cat swing assembly and thought someone here might have some drawings or experience with these machines. Your thoughts.
thanks

You might look at the swing brake. I had a swing brake disc break and it would do just what you are saying yours is doing. Also on a 325 I rented the switch on the swing brake went bad and you could not swing fast. Just a Idea???? It will be cheaper to fix, than a tooth on the swing bearing

 

[Big Iron]

Well thats never good, I would be pulling the little steel cover below the boom base and have a look see while someone slowly swings the machine to see if there is something jamming it up, or, you could also pull the swing motor for a better look inside the swing gear and bearing. Its pretty much a sure thing the swing motor would have to come out to repair either the motor itself or the swing gear and bearing group. I have a feeling there is a tooth off of either the pinion or thegear group which is why it is locking up. Swinging slowly, the greas can push the pieces out of the way before they lock up.

thanks for the info. i did not know about the "little inspection cover" at the boom base. after i found it under about 6" pf dirt i pulled it and slowly rotated the machine 360 degrees and low and behold begin picking pieces of the pinion gear out of the grease. by far and away the cheaper of the possibilities. just have to remove the swing motor and clean out about 500#'s of grease replace the gear (and rebearing the swing gear box while i'm there) and its a done deal. i was happy because i had no choice but to buy the machine (8500 hrs and a solid machine) seeing how the owner was into me for 15K and wasn't going to pay:beatsme !!!!! i offered him another 15K to square up and he took it!:cool2 anyhow by the time i'm done with a few TLC's and paint i should only be into it for about 40K. thanks for the info

 

[John C.]

Big Iron,
Is there any oil in the swing machinery? Usually the seal on the bottom goes out because you can't drain the tramp steel out off the seal and over time it will always fail.

Cleaning out that area is not so hard. There is another plate just like the one you took out, only on the bottom side opposite from the boom. It is up in the carbody behind the swivel and can be a bugger to get at. You will probably find water on top of that cover so be ready to move out of the way when you take it loose.

The pinion gear and shaft are one piece going through a big double roller bearing and it's usually a bugger to get them out of the case. If you haven't done one before it might be a good idea to get some help. If you are not careful you can break the case.

Good Luck!

 

[Big Iron]

thanks John. i will have a mechanic with the service truck to help me. i think now that i own the machine i might have to bite the bullet and go get a set of manuals from CAT for it, to help find those little things, such as the inspection plates

 

[Dan83]

Do you have any pictures of the machine? I'm sure I'm not the only one who'd like to see. Particularly under the inspection cover. I've never been into a swing assembly myself, but would like to see nevertheless.

 

[Big Iron]

i'll see if i can get some and post them. this is my first pinion gear and even if it is tough to get out, it beats the h*ll out of replacing the bull gear or rotary bearing. i'll take some pic's of the pieces too. provided i can get it done before friday as i have an appointment with a knife to do a little repair of my spine . when i am up and running in about a month:drinkup i will photo doc the repair and post some pic's.

 

[Dan83]

Ouch! Get well soon Big Iron , Here's to a speedy recovery! :drinkup

 

[Big Iron]

well i survived surgery and was back to work the following week, work being a relative term as i have been in project managment for the last 10 years:beatsme however i have not forgotten how to run the machinary. any way i have my final appt. with the doc on wed. if he releases me i will be tearing into the 320. i did get a nice surprise when i actually read the hr meter the machine doesn't have 8500 hr, but 7340 hr. anyway i will take some photos during the process. here are some photos of the machine. you can see in the background my old terex 8230 (in a state of repair) and my fruitliner 12 dump truck (385K original miles) and one photo of the project i am managing at this time. i'll post some pictures of the repair in a couple of weeks when i get released and find the time to repair the old girl