Cat E120B hydraulic drive motors

[RMCNJPE]

My 1989 E120B doesn't have the same spring in its step as it used to. From all we can tell, the hydraulic drive motors are the problem. Does anyone out there know if the hydraulic drive motors can be readily removed from the final drives for service - repair, or do the tracks have to be split and the whole motor/drive units be removed together? If possible, I would like to know what I would be getting into before getting started on the repair. It would be greatly appreciated if someone could provide this information!

 

[willie59]

I don't know that I would condemn the drive motors until I was convinced they were faulty, it's not typical that two motors go down at the same time. It could be something as simple as the seals in the center swivel. E series Cat machines are common for having bad swivel seals. I've had repair them on E70B, E110B, and E120B. Very common problem.

 

[Per Eriksson]

Agree 100%, reseal the swivel first before even looking at the drive motors again.

Cheap and easy.

 

[cps]

:exactly:iagree Just what they said!

 

[EH1]

Agree 100%, reseal the swivel first before even looking at the drive motors again.

Cheap and easy.

Hello! My 312bl has the same sympthoms but only one drive motor is weak when cold, but both will become weaker and sometimes twitchy when the machine is warm. i`m thinking this could be the swivel seals too after reading the above posts. But when you say swivel do you mean swing gear or swing motor?

 

[SOMALIWARLORD]

Hello there I have noticed in the past that cps can provide centre joint seals. I was working my hitachi ex120-2 tonight and it has spewed greasey oil all around the slew ring. Is this job i could attempt to repair myself.I would be interested in seals and possibly repair. I am about 5 miles from the Moira roundabout on the M1.

 

[cps]

Hi there somaliwarlord, i was down your way tonight just back! Its not a massive job to do your self, or i can do it for you, or you can remove the slew joint and i can reseal it for you, what ever you like!

Pm me your details if you like!

Aiden

 

[SOMALIWARLORD]

Cheers , I will maybe have ago at taking it out myself. I think I read on here that people suggested digging a hole to stand in and then tracking the digger over the top of it. I,m afraid I cant pm yet but if you could give me a shout my number is 07876743310.

Aaron

 

[Per Eriksson]

But when you say swivel do you mean swing gear or swing motor?

Neither, the swivel is located in the center of the swing gear/bearing, if you look down just in front of the swing motor you'll see where the hydraulic hoses connect to, that's the top part of the swivel.

And yes I would start with a reseal of that for the problems you describe.

 

[EH1]

Thanks Per, my vocabulary for excavator parts in english isnt all that good. I`ve been searching the forum and found different threads about this subject. Can i assume that slew joint and rotary joint is the same as the swivel as well, or am i mixing the cards completely? What exactly happens when the swivel seals leaks?

 

[willie59]

What exactly happens when the swivel seals leaks?

Hi EH1, you could call the hyd swivel any number of names; rotary joint, rotary distributor, center swivel only to mention a few. All describe the same part, the hyd component that delivers oil from the upper structure to the lower drive components which means it has to rotate in order to obtain 360 degree continuous rotation of upper structure.

The center swivel typically consists of an outer housing and a center post. The housing and post are casted or machined to provide a number of separate internal ports, each port divided by a seal ring.

Typically when internal seal rings go bad, you get oil migrating from one internal port to another, say oil pressure in one port that goes to the drive motor to drive forward. When the seal goes bad in that port, instead of sending oil to drive motor to make it drive, it leaks by the bad seal into a different port, which causes loss of drive power.

 

[EH1]

Thank you Atco for a informative post, now i understand what its all about. When i pull out the center joint it is going down trough the undercarriage as i understand. How heavy is the joint on a cat 312 you think? I`ve read that it`s an easy and cheap fix but i could always use some more info on the procedure. Thanks

 

[Per Eriksson]

On a 312C you lift it upwards and it weighs in at about 30kg.

 

[willie59]

I`ve read that it`s an easy and cheap fix but i could always use some more info on the procedure. Thanks

It's fairly simple EH1, but there are a few things you need to keep in mind doing the repair. First, loosen the hyd tank cap or filler to relieve tank air pressure. Second, and very important, note the orientation of the center swivel and hose/fitting connections, a pic from a digital camera works well. It's so very easy to remove that swivel and forget it's orientation when you go to put it back in. It helps to have proper plugs/caps for disconnected hoses, otherwise you'll make an oily mess of the project.

On some swivel arrangements, hose connections are fairly easy. Hose memory, size, and position make it clear where each hose connects. On others, it's not so clear and you could easily mix up hose connections. In these cases, it's best to mark the hoses and fittings so there will be no mix up upon re-installation.

 

[lectro88]

Hello gentlemen. HIGH JACK ALLERT !!
I've been following this and other similar threads.
Atco, Thank you for the pics. My takeuchi tb 135 has gotton a little weak on left drive.(1100 hrs.)
Been told by my local mobile mechanic this is where I need to start. Said to bog drive 15-60 seconds and if its bypassig at said swivel I will notice heat there or at drive motor or valve. (several places it could be)find the heat, in another words.

Atco. glad to see you and others survived the wrath of Oldman sending all that cold weather abroad. Thats the last time I talked to ya.

RMCNJPE and EH1 Best of luck to you both and happy digging.

 

[ngwindustrial]

I am going to reseal my rotery manifold on my E 120 B excavator (soon as the snow stops) I was wondering if it gets removed from the top or bottom..it looks slightly differant in the parts book than on the actual machine, looks like the center portion lifts out from the top? any Ideas?
Thanks.

 

[bill mcreynolds1]

I don't know that I would condemn the drive motors until I was convinced they were faulty, it's not typical that two motors go down at the same time. It could be something as simple as the seals in the center swivel. E series Cat machines are common for having bad swivel seals. I've had repair them on E70B, E110B, and E120B. Very common problem.

I have a bad swivel in my E110b, do I pull the swivel from the top?

 

[Nige]

That's how they usually come out, if for no other reason than there is generally more of the swivel already sticking out of the top than there is sticking out of the bottom.

 

[Nige]

This D&A might help. It may not be for your exact model but it was the only one I could find. I hope it will give you some idea.

 

[bill mcreynolds1]

This D&A might help. It may not be for your exact model but it was the only one I could find. I hope it will give you some idea.

that looks just like a E110
I saw a video on youtube where the guy just pulled the outer housing (from the top) and replaced the seals that way.
have you ever seen that done?