LINK BELT 1600 QUANTUM control questions

The foot and hand control for track direction hardly worked during the time my friend has owned this machine. He said he would have to nurse them to work. Now suddenly right control foot or hand lever won't activate the track in the forward or reverse direction. The tank is full and two known filters changed and still nothing. He said he took a "plate" off to check fluid and it was good yet I'm a mechanic yet know very little about this machine. The machine is out at a remote location and my buddy is heading back up there tomorrow June 25th. I won't be able to go till next week (maybe) so trying to give him some suggestions. I was wondering what suggestions I may get where to start first for troubleshooting and possibly a site or link or an email from someone with text and pictures how the anatomy of the foot hand controls to the tracks. I have an old Case backhoe yet there is no electrical for hydraulic control. The service manual is with the machine so I can't even refer to it at the moment.

Should be two sections on the pump.
One for the excavator functions and
one for travel. Need to take some
test guages and do some pressure
tests and post back. Could be the
pump, stuck relief valve, blown
sealing rings in the swivel, possibly
the brakes not releasing and the
motors are trying to over ride the
brakes.

I finally understand your post better. Service manual describes swivel and other items you described. The brakes appear to be releasing. There is 8400 hours on excavator. Operator is about 60 and says from experience he feels this machine has been ran hard. It has a service sticker with no info except it was serviced at 8000 hours. They have put less than 50 hours on it and Operator describes "power" in the hydraulics has steadily been getting worse since they bought it.

I'll look at swivel. If a internal sealing ring is blown it may only be observable by taking apart I expect?

If main pump pressure reads low if I understand correctly, there could be internal leakagebypassing in a variety of components. I was told the main relief valve will be by swing motor? So still trying to figure out where the main relief valve is. Maybe its being held open by a piece off brass filing?

The boom will not lift if boom and dipper fully extended with bucket full. Operator said he would have to empty bucket by 1/2 to get boom to come up so maybe packing in boom bypassing?

Operator said machine does not have the power he would normally expect to "stand the machine on end". He though dirty filters or a weak pump may be the culprit yet I found out pump is ok.

He said excavator would travel fine straight or in reverse. Yet when going to turn it would turn very slowly and not quickly. It seems by the operators opinion machine struggles to turn when forwarding one track and reversing the other, and when using boom when fully extended with dipper.

There are five hydraulic filters (all new filters ordered):

Pilot drain filter. It is a small paper pleated filter and was very dirty with super fine black substance. Washed out 7 times with gas before it came cleaner.

Nephron filter. Appear to be made of card material and looked collapsed inside. I learned this may only filter 3% of hydraulic oil at a time during operation.

Drain Filter. A spin on filter beside hydraulic tank. It appeared to be full of rusty water. About the size of a regular v8 engine oil filter.

Return filter in tank. Brass filings were small but easily must of passed through return filter. It appears to have a metal screen around it and possibly pleated inside with fine screen material? I haven't cut it open yet. Operator said he checked it last fall so maybe brass filings fell into tank then??

Suction filter. Held in bottom of tank with a spring loaded ready rod. Appeared not to bad except for brass filings in outside of bottom pleated edge area.

The guy that runs the machine is older than me and wanted me to check filters first. They were all dirty. I pulled suction filter up out of tank and it was filled along bottom pleats with brass filings. Shop in town told me pump would be good place to check for brass wear and tear. So I took pump off engine and shop checked it all out and its fine. Brass filings could be from an earlier pump failure because I noticed pump had color coded wires on it from a past mechanic when is was owned by someone previously. Yes the pump has other items attached to it so I expect larger section is for excavator swing, boom, dipper, and bucket. Other sections for track travel. I'll be going to put pump back on engine along with new filters, and clean out tank. Then I will tell operator I will be completing the two travel motor and swing motor drain tests as outlined in manual. When I pick up pump I will ask about sections of pump and purpose. I will clean out all suction lines to pump. I want to thin out remaining hydraulic oil with a non flammable solvent or cleaner and then suck it out. Any suggestions to thin out oil and suck it up with a shop vac? I'm thinking shop vac my light up! I drained the 25 gallons in hydraulic tank and definite black tinge to oil as it sits in buckets.

I will ask about these fittings on pump yet thought you may know what fittings these are for and the name of the type of fittings they are. I have a bucket of misc hydraulic fittings. I bought two oil filled gauges and a ball valve with hose to check pump pressures. I don't have manual with me but one gauge is for testing main pump and the other I believe for track motor tests.

The manual refers to the fittings on pump as "JIS B2351 0 type". On the net they look like a fitting that threads in with a sealing o-ring on base of threads.

I'm wondering what these 2 hex shaped caps are for on main pump ports, and this male fitting that resembles a male hydraulic fitting for a female fitting to quick-couple to it yet don't know what fitting type its called. The hex caps are approx 15 mm (15 mm wrench fits best) and the male fitting measures 12.8-13 mm in dia., and 16.4 mm long approx.

I expect one of them may be the air bleed port?

First thing I would do is make sure there is nothing under the pedals impeding their movement,ie see the controls are right,then jam something in one track and lift the other off the ground,now try to drive the jammed track while watching the other,if the other moves the seals in the swing joint are shot and the oil is leaking internally,nothing for it but to reseal the joint.
AJ

(quoted from post at 15:36:10 07/23/19) First thing I would do is make sure there is nothing under the pedals impeding their movement,ie see the controls are right,then jam something in one track and lift the other off the ground,now try to drive the jammed track while watching the other,if the other moves the seals in the swing joint are shot and the oil is leaking internally,nothing for it but to reseal the joint.
AJ

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Thank you. I will do that.

Tried that today AJ. In high speed mode at full throttle as I call it, nothing else would move. In low speed mode as I call it, the pin I was using to jam sprocket kept coming loose so need to find a bigger dia. pin tomorrow.

I did attach a pressure gauge to this quick connect behind boom. I think its the main control valve body and gunge said 1000 under full throttle no load. Going to put a hose in series tomorrow so I can see gauge by cab. See photos please and reply what you think that component is that gauge is testing. Photos all apear sideways. Gauge actually is vertical on machine

I also noticed today under full throttle, in high speed mode one track will not go forward as I activate other track to go in reverse. Both tracks won't move. You can hear engine load up though. In low speed mode one track will turn fine and the other stays still when hand foot levers are actuated, one in forward and the other in reverse. Yet have to double check that in am.

Looking at this photos I'm pretty sure that's main relief valve with lock nut to right of pressure gauge fitting. the orientation to the pressure gauge port looks very similar to schematic in service manual

Maybe that's why tracks don't move properly? 1000 psi is 25% of what reading is supposed to be if the gauge is actually reading main relief pressure. I've already had main pump off engine and shop it checked out to be fine.

If one track moves when you activate the other the the oil is bypassing,if you can track the machine and let go of the controls sudden does it stop abrupt like it used to or does it feel like it's cushioned that too indicates the swing joint seals,they are wearing parts and do require changing from time to time.
AJ