Drott Skidloader

tpmx

New User
I have a International TD-6 crawler loader that has a Drott bucket on it.
I am having problems with the front bucket.
It developed a problem where the loader wouldnt raise.
It will curl fine,I can lift the machine several inches by curling the bucket under and it works fine.
The problem is that it will not raise.
It started raising slower and slower until it wouldnt raise at all
I took the valve apart and found the chrome worn away on the lift spool in 1 area.
I sent the spool out for repair and now have it back together.
The loader will lower but not raise.
By lower I mean I can pick the machine up a few inhes with the loader but cant raise the bucket at all.
Any ideas what possibly could be going wrong?
 
One of the lift cylinders is leaking by the piston packing in the cylinder. Cylinder needs repacking. You can block off the line going to the lift end of the cylinder on one side to determine which cylinder needs packing.
 
Thanks JM
never thought about that
I was convinced the problem was still in the valve.
Would the cylinders still work in the opposite direction?
It seems they have good pressure when running the loader down because they lift the machine right up .
Just wont run the opposite way at all.
It make sense,when I noticed the loader was running slower up i would run the loader all the way up and it would jerk like there was air in the system
After running the loader up and down a few times it would work ok for awhile
 
When you lift up the front of the machine, does it
creep down fairly fast? If it holds, it's not
likely the cylinder seals that are the problem. If
the seals in one or both cylinders were so bad
that it wouldn't even lift the boom, they would
also cause the boom to creep pretty fast when
there was down pressure on it. Can you switch the
hoses from the bucket valve to the loader valve
and see if it will lift? That could help you
determine if the valve was the problem. Putting a
T in the hose and a pressure gauge would also
help. Does the engine labor when trying to lift
the boom? You could have a restricted hose or
internal leaking in the valve body.
 
When i lift the machine by putting down pressure on the loader it will stay there till i hit up,then it just lets the machine on the ground but wont even try to raise the bucket.
The lines are preformed steel and will not switch over to the other spool.
The only other thing I was going to try was swithing the tilt lines over to the extra spool that is not in use than switch the lift lines over to where the tilt lines were.
Even this may be impossible with the prefab steel lines,theres just not much give in them.
I really think the valve is leaking internally or possible a relief valve is opening because when I try to raise the bucket I can hear oil inside the valve going somewhere
I havent ruled out cylinders yet but just dont understand why they have down pressure with no problem
i could switch to another valve but it would change everything from original and I would really like to keep it oem
If anyone knows of a good valve i would be interested
Mine is a TD6 Drott Skid Shovel but not the 6-1 loader,just a bucket.
The valve has 3 spools but just uses 2 of them
This machine belonged to my uncle who purchased it to clear the land and build a pond when he and my aunt first bought their ground.
It did alot of work for him and just about the time he was finishing up one of the clutches went out.
He tore the dozer down and went thru the steering clutches and decided the engine was tired enough so he had it rebuild.
He used the dozer very little after than other than for some finish work around the new house.
He passed away a couple years ago and I told my aunt I would like to buy the dozer to which about a month later I bought it.
It runs like new and operates great till this started.
Needs blasted and repainted plus a better set of tracks to be pretty nice.
I have the manual for it if anyone would ever need part numbers.
Thanks for all the help so far
Other than building a few logsplitters over the years I have very little hydraulic experience
 
One other thing I thought was that the lift spool had what I think may be a relief valve in the lower end of the spool.
Is this a relief valve to keep from over lifting with the loader or is it for some other reason?
The only thing I could think was possibly that spring was weak and allowing the valve to open on the lift cycle.
Not sure why else that would be in that spool
I wish I would have taken pictures of the valve apart so I could post them.
just thought the worn off chrome was my problem
 
Try just slowly moving the vlave until it starts to lift. Once it starts moving hold the vlave in that position.

If it continues to lift there is still a valve problem

Rick
 
(quoted from post at 09:39:01 12/03/12) Try just slowly moving the vlave until it starts to lift. Once it starts moving hold the vlave in that position.

If it continues to lift there is still a valve problem

Rick

Thanks Rick
I will try it tonight and try to get a better feel
For how it is acting
Do you happen to know what the check or relief valve in that spool is for?
I am going to check also and see if i have oil flow from the valve
When trying to lift
I need to determine if i am getting oil from the valve to the cylinders
I dont think the motor rpm vary at all on the lift cycle
Will pay better attention tonight
 
tpmx, What I am about to write is somewhat generic because I'm not sure what your valve has but here goes.
The spring and poppet you talk about in the spool may be what is called a regeneration valve and the purpose is to refill the upper end of the lift cylinders when the boom is dropped rapidly. Not sure how it may apply to your problem.
Many hyd valves have what is referred to as port reliefs or circuit reliefs for each operation. It would be common for hoist up to have one to protect the cyls and boom if when up something fell from above or a bank would cave in. If this relief was bad or had a broken spring it would cause your problem and would not effect the down operation.
Another thing, is it possible that the linkage is worn to the point that the lever is hitting the frame work before the spool is stroked enough? I have seen this before.
I doubt cylinders if you have down pressure but they could be tested for bypassing.

As I said these are generic comments and may not apply to your specific valve.
Good luck, I'm sure you will get it figured out.
Dennis
 
[quoKte="Dennis K (WA)"](quoted from post at 12:31:06 12/03/12) tpmx, What I am about to write is somewhat generic because I'm not sure what your valve has but here goes.
The spring and poppet you talk about in the spool may be what is called a regeneration valve and the purpose is to refill the upper end of the lift cylinders when the boom is dropped rapidly. Not sure how it may apply to your problem.
Many hyd valves have what is referred to as port reliefs or circuit reliefs for each operation. It would be common for hoist up to have one to protect the cyls and boom if when up something fell from above or a bank would cave in. If this relief was bad or had a broken spring it would cause your problem and would not effect the down operation.
Another thing, is it possible that the linkage is worn to the point that the lever is hitting the frame work before the spool is stroked enough? I have seen this before

Thanks
I am headed home from work and will see what i can determine

I doubt cylinders if you have down pressure but they could be tested for bypassing.

As I said these are generic comments and may not apply to your specific valve.
Good luck, I'm sure you will get it figured out.
Dennis[/quote]
 
tpmx,
I just thought of another possibility for the spring etc on the back end of the spool. Could be the detent assembly which is there so the handle will lock into the raised position until it reaches a predetermined height at which time it will kickout by itself. If that is what it is it would not have an effect on your lift unless assembled wrong and not allowing the spool to shift totally.
Maybe some pictures of what you have would help identify the valve.
Do you have any manuals for the unit? Parts or service.
Dennis
 
I have manuals for the machine but not my hydraulic system.
I ran the machine tonight some more and I do have go pressure/force with down and curl both ways on the bucket,
I took the handle off the spool and operated the spool through the full stroke and its no different,appears the handle is allowing full travel
I broke a fitting loose on the valve going to the loader lift cylinder and have fluid oming out when the valve is in the lift position.
Without a gauge its useless because I have no idea of how much volume or pressure is coming thru.
Still suprises me the loader will not even try to lift at all,no movement in the cylinders what so ever.
I do hear oil traveling somewhere within the valve when in the up position.
Though maybe it was going back to the tank but thats not the case.
Sounds like its just circulating thru the valve.
I do notice the hydraulic oil looks to be full of air just not a solid color like oil would be.
The valve is a
HYDRECC
V400p320
H2627
I will get a picture of it tomorrow while its light out still
Thats again for taking the time to help with your responses
 
There might be float position on the boom valve. If
it's going into float position would cause it not to
lift.
 

It does have a float position on the lift spool.
All the way forward is float,back slightly is down,back more is neutral all the way back is lift
This is interesting but how would it be going into float with the spool in the lift position.
I am asking this because I am not sure how the float actually works
 
Internal leak in the valve? I'm not sure but it
would account for it not lifting. Float opens up the
ports in the valve so the weight of the boom and
bucket follows the contour of the ground when back
blading.
 

An internal leak in the valve is what I am leaning towards
I am going to ser if i can switch the lines over to the extra spool
And see what happens
Should tell the story
 
Sounds like one of two possibilities; First, check
to make sure that someone hasn't switched the
"raise" & "lower" lines at the control valve.
Second, check the "over-pressure" relief valve on
the "Lift" side of the control valve; if someone has
had the valve apart & forgot to put back the check-
ball or spring,the Hyd. fluid would by-pass the lift
side of the valve.
 

The lines are correct, they are prebent steel lines at the valve so its hard to get those reversed
There is one large spring loaded valve which i believe would be to set pressure on the entire system
It is in the top side of the valve on the pressure side
The only other one is the one that is in the lift spool itself
That on i am not sure of its function
Another has stated its possibly a regeneration plunger
Possibly a relief valve on the lift spool
It connects the lift port on the spool to another port if it were to open
I have that spool back at to look at it again
The plunger seat looks good plus the seat surface on the plunger seems ok
You can see a wide line where they have been making contact
I put the plunger back in the spool with its return spring and filled that cavity in the spool with a light oil to see if it leaked pass the plunger and it does not
This leads me to believe the plunger does seat
The next thought is if the spring is too weak with age
 

Well today at work I remachined the plunger seat,
Hand lapped the plunger to the seat and made a small .125 shim to tighten up the plunger spring.
i put it all back together tonight and still the same thing.
I started now moving the prebent lines over to the extra spool.
I was afraid they would never have enough play in them to move but seems they will.
I will post what happens next.
I will know if the problem is internal in the valve or not.
 
Does it have a pressure gauge tap in the pressure line or fitting at the valve? If so hook a gauge to it, maybe 3000psi and see what you have. Cap the fittings at the valve going to the lift cylinders and check press. At least this would isolate it to the valve. Not sure what the pressure should be but probably around 2000psi-2200psi.
Haven't been able to visualize how it could be in a cylinder based on what you reported but stranger things have happened.
good luck
Dennis
 
I've been following this discussion. It seems to me that even if there is a badly leaking piston seal in one of the cylinders, you would still be able to detect either by slight hose movement or by listening at the cylinder whether the valve is sending fluid there. If there is a relief built into the connector at the cylinder, as there is on my Drott skid shovel's 4-way cylinder, you could also detect flow there the same way. The main valve relief must be OK because it protects all circuits, I think. Will be interesting to hear about your next experiment.
 
Ok this morning i switched the lines over to the other spools.
I have the same identical problem.
I still cant picture how a bad packing on the piston would allow the cylinder to still have down pressure ,seems it would bypass in both direction.
Now to see if theres a relief valve at the lift end of each cylinder.
My other thought is what if a hose to one of the cylinders was internally restricting oil.
Would the other cylinder still try to lift the loader or would it be mechanically
impossible?
I know the hose to the lift side of the right cylinder is only a few years old but the other is probably original or at most pretty old.
I cant see a valve any where on the lift side unless it built inside the cylinders somehow
 
I suppose that if one line were plugged, the other would try to lift, but it would face some suction pressure as the other cylinder would be creating a vacuum where fluid (or air from the rod packing) were not available. Here are my latest thoughts:
1. Try very hard to listen for any fluid movement or even a twitch in the hoses at the cylinders when you try to lift. Maybe crack a hose at the cylinder on the pressure side for lift. I think you will get something.
2. The pressure may not be enough to lift, even though you can get downpressure. Your main pressure relief valve is presumably a pilot operated relief, and there is a procedure for adjusting that. I made a tool for mine and adjusted it up. If you don't have a diagram, I could send you the page from my IH TD340 hydraulics manual, probably slightly newer than your machine.
3. There could be a problem with a check valve in the valve body, either blocking flow or somehow relieving pressure through another circuit.
4. The pump could be too weak to lift.
 

Ill do some further testing.
I am going to drill and tap a pipe plug for a gauge and pressure test the original lift port now that I can access it easily
This will tell me whats going on with hopefully the pump and valve.
Is funny there is no reaction in the cylinders or hoses on the lift stroke.
 
I would still inspect those poppet check valves in the top of the valve body, at least if it's like mine. That could explain the noise you're getting in the valve.
 
The check valves are very simple and under hex plugs in the top of my valve, perpendicular to the axis of each spool. These are separate from the relief valve. I could send you a schematic of mine if you would like. Just send me your Email address. Mine is open.
 
Ok with winter over I am back to working on my dozer
fired it up tonight and brought it up to the garage where I can work on it.
I am curious as to the purpose of the large coil that is tied into the loader hydraulic lines.
It appears to be some type of "cushion" for the hydraulic system and wonder if it is on the lift side of the loader or what its purpose is for.
There is a handle there but is not hooked up to anything.
Anyone have any insight as to the purpose of this ?
 

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