Stupid Question of the Day

[watglen]

Great drawing.

It was only after i purchased an excavator that i learned this simple yet mysterious design. One small detail left out is how they handle the alignment problem. How do they maintain the precise fit in the hydraulic swivel, while allowing the house a lot more loose play where is connects to the track frame.

On my volvo the bottom portion of the swivel is hard mounted to the track frame dead centre in the machine, while the upper portion is only loosely rubber mounted to the house frame. When you swing the body you can see the slop in this connection.

Pretty ingenious if you ask me. I wondered about it for years.

 

[heavylift]

like Atco said Cranes are way different,,,, especially the one motored cranes... about the only thing they don't send thru the swivel is water for a heater.... most have the diesel or propane..
can you imagine setting in your car ... and all the functions in the car going thru the swivel.. turn the headlights on...turn signals... gas pedal... brakes.... starting the engine .... forward and reverse.... think of that 6 way power seat and driver 4power window controls as the outrigger and beam controls

 

[OCR]

Stupid Question of the Day:

Ok...what's the story with that?

"thank you very much"

That's just a "figure of speech"... Cat fixed it once, and it seems to be leaking again... the travel is getting weak.

It was nothing pertaining to you...


OCR



But the edit was...

 

[John C.]

Drott 40s, 80s and cruise cranes were about the worst I dealt with. The 80 barrel assembly was huge but you had room to work. The 40 was small and could be handled but the electrical and air was a huge pain. The barrels were soft steel and the seals would cut grooves in it. They didn't last but a couple of thousand hours and you had go through all the crap again. Track machines are breeze.

I've got a kinship with anyone that had to go through that.

Oil running down your sleeves into your armpits, electrical shorts that could be anywhere from the switch in the cab to the starter on the engine and air brakes that didn't work and the operator forgot to tell you that before you went to unload the thing off a low boy.

You don't have to fix many of those before you start looking for another way to make a living.

 

[Aardvark]

Centrejoints

Heres a couple of pics.
Up close and personal with my joint haha.
No 1 from under the digger, still in-situ.
No 2 joint removed from digger.
No 3 looking @ bottom of joint.
top two fitting go to blade,
angled fittings on each side go to respective track motors (forward/reverse)
tee fitting on very bottom is case drain from track motors
from memory smaller tee @ back of joint was for two speed track.
the tee fitting on top of joint one side was case drain from swing motor, the other side was return to tank
It's a weighty sucker @ 20 odd kilos. Bit of a struggle trying to hold it in place whilst getting a bolt in it all the while laying on your back with bent arms phew!
earned one of these after that effort:drinkup

 

[T_Gunn]

There is one other hydraulic line that goes to the track motors for the spring applied hydraulically released brake on each motor. When you stop moving, there is a set of spring applied plates that come on to prevent the machine from creeping back and forth while you are digging. When you use the travel pedals, hydraulic pressure is simultaneously applied throught the brake release lines via a shuttle valve to push against the spring applied brake, allowing the travel motors to turn the gearbox. It is considered 'failsafe' because the default is to have the brake locked on if there is a loss of hydraulic pressure to the system. To see this in action, lift up one track with the boom, track to full speed and let off the pedal quickly. The track stops almost instantaneously because the failsafe brake loses hydraulic pressure and the spring take over right away.

 

[powerjoke]

Correct me if i am wrong,

But i thought i read somewhere that the new bladerunner's were radio controlled :beatsme ?

Pj

 

[John C.]

Tracked machines use travel pressure to release the brakes now days. Basically it takes a couple of hundred pounds of main pressure trying to roll the motor which is teed off to release the brakes.

The last separate brake line I saw was on a 40 Drott.

 

[Copenhagen]

Tracked machines use travel pressure to release the brakes now days. Basically it takes a couple of hundred pounds of main pressure trying to roll the motor which is teed off to release the brakes.

The last separate brake line I saw was on a 40 Drott.

Say for example, a tracked machine quit running. Would this mean that you would have the ability to pull it onto a trailer or to a different location? Or would you have to dismantle the track motors?

BTW, this should be noted as Stupid Question of the Day 10-04-09.

 

[JimBruce42]

Say for example, a tracked machine quit running. Would this mean that you would have the ability to pull it onto a trailer or to a different location? Or would you have to dismantle the track motors?

BTW, this should be noted as Stupid Question of the Day 10-04-09.

I'm gonna take a shot in the dark here and say you'll be pulling the final drives apart. I know a track loader isn't a track hoe, but we had a 963c blow a hydrostatic pump a few years ago in the quarry and had to pull the finals apart so it would free roll (or is it free track:beatsme). took a 988 to pull it off the pile it was on and push it onto the lowboy.

 

[spitzair]

I worked on a Bantam wheeled crane once, similar to the Drott rubber tired excavators, what a nightmare that swivel was! Unless it was in one certain spot you couldn't crank the engine over, luckily it had a seperate crank button on the lower unit, I guess somebody else had problems with it too...
Powerjoke, a Radio controlled blade? That's an interesting concept! They'd have to have a valve unit in the lower house and some kind of electrical power supply going down there to make it all work...

 

[[-Agent-]]

Say for example, a tracked machine quit running. Would this mean that you would have the ability to pull it onto a trailer or to a different location? Or would you have to dismantle the track motors?

BTW, this should be noted as Stupid Question of the Day 10-04-09.

I thought there was a pressure release switch somewhere, since I have seen them pulled onto trailers before.

 

[John C.]

To move a dead machine you have to remove the outside cover on the final and remove the sun gear in the planetary gear set. It only takes a few minutes to do but you will loose all the oil.

It's not a dumb question either. I don't know how many times I've had to do that to move burned machines. The people in suits don't know anything about machines but sure do raise cane when they get a bill for services they don't understand.

 

[gatorguy]

As long as your sprocket is circular on the inside and not wavy like some models you can just take the bolts out of the sprocket and let it rotate around the final drive. It's not really faster than taking the final drive apart but you dont have to deal with the oil or buy new gaskets. Just make sure the tracks are tight and try not to turn it too much while pulling so you don't run the sprocket off the final drive.

 

[lgammon]

this reminds me of a contractor that bought a mini that we work for. he asked the same question when he bought a used mini and dad looked at him and said well you can only turn them one direction 10 times till the hoses get tangled up and pull the hoses apart. did the guy that sold it to you tell you how many which way it was when you got it??? and he was scared to death for a few minutes till we told the truth

 

[hokuto]

Greetings all
thanks for your forum
this is the second time i have found the answer to my questions regarding my excavator
i have a small Hokuto 300 HD - 2
i find it really handy on my small farm
i have had it approx 1 year and have today noticed a tell tale drop of hyd oil following my movements
i have tracked it down -- you bet to the swivel
it took me longer to find out what it was called
thanks to your forum the mystery was solved:notworthy

now my quandary begins
it is only leaking oil when rhs track is turning
the leak seems to be a seal in the top of the unit

it seems reasonably straight forward to remove the swivel from below

however i am not sure what i will find when removed and perhaps dismantled
it seems to be not as complicated as some of the other units discussed in this thread

i have some experience with repairing hydraulics and have good engineering workshop with some metal machining equipment

without knowledge of availability of spare parts for this make of machine
does anyone think that the unit may be serviceable using generic style O rings
or is it advisable to take the unit to hyd specialist

so far i dont think there is any major damage and hopefully a new set of seals may fix the leak

the tracks are both working well ... perhaps i have noticed from the beginning that one was slightly faster than the other but very marginal

so from a newbie thanks again for your forum and look forward to your suggestions

 

[willie59]

Welcome to the forum hokuto. :usa

Before you begin your repair, if you've not already done so, you need to identify your fittings and have a sufficient number of appropriate plugs and caps for the hoses you disconnect to keep from making a terrible mess with oil. And before you start, remove the cap from the hyd reseroir as most excavators have a pressureized hyd system, vent off this pressure. Next, take a center punch and mark your hose/fitting connections. Choose a hose as a starting point, punch a single dot on the hose fitting and the matching swivel fitting. On the next hose fitting, punch two dots, the next three, until you've marked all your fittings. Be sure and note how the swivel is oriented when installed, you don't want to reinstall it and try to decide, "did it mount this way...or turn this way???" The rest is pretty simple to remove swivel. Once you get it on a bench, you'll probably find some sort of retainer ring that holds the swivel assembled, it's usually pretty easy to remove center rotary joint from swivel housing, you occasionally find some deteriorated o-rings that hang things up, but they usually come apart with no real complaints. Again, note how the center rotary joint is oriented in the swivel housing. As for the seals, they vary.
Some just use typical o-rings. I have also seen them use seals like crown seals, Hallite seals, TP seals, and even T seals. But you can't fret over being able to obtain seals, because if your swivel is leaking you don't have a choice but to take it apart and see where it takes ya. I can't tell for sure, but it looks like you may have pipe thread fittings in the swivel, but if you have any o-ring boss fittings now is the time to replace those o-rings as well. Good luck and keep us posted.

 

[hokuto]

It is really something to have all this wonderful knowledge available.

Atcoequip thanks for your reply
your advice is well received
i would like very much to make sure i don't make any unnecessary mistakes and your advice reinforces this point
i make a point of digitally photographing every thing i pull apart from every concievable angle as well usually i dont need them on reasembly but its a bit of insurance just in case.

i have removed some of the controls blocking access and cleaned up everything from the top
i have not cracked any hyd lines and am in no hurry to do so until i have made sure i need to

with a better view and a clean up i can see the oil seal that appears to be leaking and have noted it in the photo attached
i can read the identification numbers on it and wonder that because it doesn't leak that much perhaps i should try replacing it while still in machine and all hyd lines attached?

my next step is to video the leak in action and seek your opinion:notworthy

the machine is quite old and the previous owner mainly used it to infrequently unload drums from a truck...not a lot of swiveling i imagine....
but now i am using it quite a bit and do a lot of swiveling ....so perhaps this outer seal has had a bit of a fright with all the swiveling and being so old:beatsme

it would seem that the unit has 2 extra ports at the top which have blank plus in them i have not checked underneath but i wonder if they could be used for a blade hyd's? :drinkup

regards
shane

 

[willie59]

Hmm, hard for me to tell in pic, but looks like a rather unique swivel. That looks like it might be a canned lip seal in the pic. That would not be a pressure seal as much a seal to keep contaminents out of swivel, water and dirt. The pressure seals will be insided at each port ring. Once the oil goes by a failed port seal, it will force by that lip seal. Time for new seals. You may be able to drop the center rotary joint out of the swivel housing, but keep in mind, your going to be leaking oil until and probably while you put it back together, might get a bit messy. Most likely, the two unsued ports on the swivel would be for a unit that has a blade fitted.

 

[hokuto]

Yes atcoequip i agree
I was hoping for less suspense but alas i must face reality , it should be done properly now before it causes more damage.

In oz we have a saying "suck it and see"
you described it as "take it apart and see where it takes ya"
I just hope when i do dismantle the unit it has seals that are available

my biggest problem is safely elevating the machine enough to get underneath to remove hoses and retaining bolts
i think there will be ample room to lift unit up through cab
which will be better than dropping it out the bottom:Banghead

if i can get the replacement seals it may be time to renew both the hyd oil and filter as i have not done that since i purchased the machine

i cannot find either volume or type of oil to refill with....have you any suggestions regarding replacement hyd oil in an older machine like this or tips on the approach to changing the oil ....such as emptying rams etc

i will post the video as it does show clearly the leak..... i just have to work out how you tube works:bash

regards
shane