My Cat 299D2 XHP blew a hydraulic hose that goes to the left track drive motor. I replaced the hose and most of the hydraulic oil. I could see that the old hose seemed to have been rubbing against the metal where it exited from under the cab to the left drive. The day after replacing that hose it appears to have blown a hose on the other side going to the right drive motor. The first hose blew just moving the machine with a grapple attached but I hadn't done any work yet. The second hose blew while I was mulching a stump with my Fecon mulcher so I was really stressing it. After years of never having a hose blow, this seems like an extreme coincidence. Do I have some kind of relief valve that is bad?
Examining the rupture/ leak point is where to start. Abrasion? Corrosion?
The first hose that blew did seem to have some abrasion from rubbing against the opening leading to the drive motor. The second just seems to have a rupture. Both are the smallest of the group of hoses leading to the drive motors on each side and are only rated at 2250 psi.
Where did you get the 2250psi figure from, marked on the hose.? Are you talking about the case drain hoses by any chance.? I had to guess at a S/No but which hoses are they on the illustration below.?
This is the first hose. Part number 345-4633. I believe it is 13 on your diagram. I believe the hose on the right side is the same, but will verify today. I'll post my serial number shortly.
The serial number is DX200548.
345-4633 is one of 4 hoses (2 each side) Ref #15. #11 & #13 (1 of each) are handed LH & RH side of the machine. Attached the drive system hose parts breakdown for DX2 machines from first built up to 1837. I believe that the four hoses #15 are for the parking brake release and the 2-speed travel, and that the hoses #11/13 are for the travel motor case drain lines. If I am wrong I'm sure someone will correct me.
Remove your protective covers on each side and examine all your hoses. We just had the same issue and had to replace (2) hosed to the drives withing 40 hours (1400 hours on machine). After removing both covers and examining all the drive motor hoses we found several areas severely worn down to metal. One hose was under the cab and blew because it was rubbing against another hose by the hydraulic motor. When we replaced the hose I used plastic hose wrap where it exited the side. I'll be replacing another hose shortly, because it is worn and down to metal, but decided to wait until it blows. Each hose cost us $500 to have made at hydraulic shop.
I'm about to go back out to the machine and verify that the second line that blew is also the case drain line on the other side. Can anyone tell me if there is a filter on these case drain lines that could be clogged and causing high pressure? I just hope that the pressure didn't get so high that I've blown the seals on either drive motor. I'll check for any other worn hoses but it seems likely that it is a problem with excessive pressure in the case drain lines.
Based on the Part Number in your photo a few posts back I don't think that line was a case drain.
Nige, didn't you stated that "hoses #11/13 are for the travel motor case drain lines" and that #11/13 were 345-4633 which is my part number.
No I did not. What I said was "345-4633 is one of 4 hoses (2 each side) Ref #15”. See post #7 above for full detail.
Nige, Sorry I misunderstood. #15 does appear to be connected to the motor at the location of the hose that failed. I can't tell from the diagram where the other end connects, but it was connected to one of the two t-connectors at the floor. I'm about to take a look at the second hose that failed. Thanks for your help.
The four hoses that go from the two t-connectors to the respective travel motors are all identical - Ref #15. Hose #11 (LH side) and #13 (RH side) go all the way from the travel motors back to somewhere close to the hydraulic tank. That's what makes me think they are the case drain lines. If you open the attachment I posted earlier you can blow up the illustration for a better view.
Just finished looking at it and you are correct. There is one hose from each side that blew and both of them are part num 345-4633 and are both connected to the same t-connector. The other end of that t-connector is connected to the top of the main pump (I guess) with a hose with part number 345-4833. So they are not the drain lines.
In the picture above, the elbow at the top is connected to the t-connector with the two blown hoses. The second hose blew in a spot in the open with no abrasion. I'm hesitant to just replace the hose since there seems to be a pressure problem. Is there a relief valve for that port?
I used the machine for at least an hour before the second hose failed.
It depends if it is the 2-speed circuit or the parking brake release circuit, and I’m not sure which one is which.
I'm not familiar with the 299 but if it's a closed loop circuit then the casedrain could very well return to the pump. If there's no obvious external damage to the hoses that causes them to blow then a casedrain flow test should be done ASAP. Worn hydraulic motor internals could be the cause and blown hoses are the symptom. Test each motor individually because they're interconnected and 1worn motor can damage the other side hoses.
According to the hydraulic schematic the travel motor case drains return direct to the tank. Apart from that it's already been established that the 2 hoses that have blown so far (which both come from the same tee) are either on the 2-speed or on the parking brake release cicruits. I'm just not sure which one's which based on the hose layout shown in both the illustration and the attachment in Post #4.
Nige, Could you attach the hydraulic schematic? I see the the illustration that you posted and attached, but I don't see the schematic. Do the 2-speed and the parking break release circuits both go back to the pump? Is it surprising that the 2-speed travel lines are only 3/8" 2250psi lines? Are they only used when the rabbit speed is selected? I'm not using the rabbit speed btw. I may well be completely misunderstanding what the 2-speed lines are.
If these are the parking brake lines, could it be that the Parking Brake Solenoid (Part number 278-8743) located on the pump near the point where the line returns from the T is not functioning and causing high pressure in the line?
Attached the hydraulic schematic. There is only oil pressure in the parking brake lines when the solenoid is activated. The brakes are spring-applied and released by hydraulic pressure.
I ordered a new hose along with the fittings necessary for me to hook up a pressure gauge and relief valve on the line. I'll get an extra hose long enough to mount the gauge and relief valve outside the cab so I can monitor it.
Thanks for the hydraulic schematic.
Does anyone have any documentation on that drive motor, part 442-5642? If I had something showing the function of each port, that will tell me the function of the line that is blowing. I know which port the line is connected to. It is also shown somewhat by the illustration that Nige posted. It just happens to be the only #15 labeled there on the left drive.
Just be aware that the illustration posted by HMC above is oriented the opposite way in relation to the parts image in Post #4 on page 1. Physically on the machine the 2-speed and park brake release connections are at the top, the case drain connection & speed sensor at the bottom.
Thanks Nige. And thank you heymccall for posting that very helpful doc. I'll take a look at the machine shortly and identify the exact port.
Just looked and it is in fact the brake release port. I should receive the new hoses, pressure gauge, and relief valve this weekend. If the pressure exceeds the 2250 psi relief valve, does anyone have any suggestions on what could be causing the high pressure on this line?
Nige previously pointed out that the brake solenoid is activated to allow pressure into the line to release the spring brake. I know nothing about valves, but does the valve controlled by this solenoid regulate the pressure that goes into the line. If so, could a defective valve allow too much pressure in?
When are hoses blew, it was because the hoses had rubbed against each other. When we installed the new hoses, we made sure to turn the elbows and then tighten them so the hoses did not touch each other. That's probably the reason your blew. When we removed the hoses, it was obvious that the hoses rubbed each other. You could not see the wear on the hoses when they where installed. Its tight.
I think (and hope) that my problem is going to be the same problem experienced by uglyguy. The first hose was definitely worn where it went through the opening with the other hoses to the drive. The fact that the second hose that blew was hooked to the same t-connector and blew within an hour of replacing the first hose may mean that the problem is both worn hoses and that something changed slightly with that valve. Maybe a sudden slight increase in the pressure passed by that valve caused both worn hoses to blow within hours of each other. I believe the min burst pressure on those hoses when new should be 9000 psi even though the working pressure rating is 2250psi, so you would think that neither hose could have been healthy. I'm still waiting on the fittings for hooking up a pressure gauge to test the output of that valve.
That's not quite correct. The tag on the hose says "WP 2250psi". That translates as the [expected] working pressure is 2250psi, not the rated pressure. The 345-4633 Hose As is manufactured from Cat XT-3 hose. This type of hose has a maximum working pressure of 4000psi. The minimum burst pressure of XT-3 is 4 times the MWP, i.e. 16,000psi. The hose must not fail when impulse-tested to 133% of the maximum working pressure (so 6000 psi) for 1 million cycles at 250 DegF. I think it should stand up.
Nige, would you say then that if I'm testing this with three new Cat hoses and a gauge, that I don't need to bother with a pressure relief valve? Is it even possible for that pump to output a pressure that would burst a new hose?
Remember that hose only has pressure when the parling brake is released. I can't envisage how an additional relief valve attached to the test equipment, which I think is what you are proposing, would work under those circumstances.
I'm just installing an extra T and mounting the pressure gauge and relief valve to the cab where I can see them when I release the parking brake. I'm trying to avoid spewing a huge amount of the hydraulic oil before I even realize there is a problem like the last 2 times.
I had the same issue and lost entire Hydraulic fluid (twice), before I took an hour to hand dig all the muddy oil out and took towels and cleaned it out really good. That way I could see where the leak was. I then lowered cab. and started skidsteer up for 2 seconds and then shut it back off. Then raised the cab and it was very clear where my leak was. Someone on the forum told me to do this, and I wanted to avoid cleaning, because I knew it was going to be a real pain since it was broke down in the woods. I was thinking it was my pump! Glad I took the advice and cleaned it out.
After the first leak, I was able to prop the cab up slightly and climb in and crank it up while someone looked in from the side to spot the leak which was very obvious. Mine is also sitting in the woods with a mulcher attached, but I have the new hoses now and will get it fixed if it ever stops raining.
Hoses rubbing through where they pass through the frame is such a common issue on the Cat machines its not even funny. I would make a point of armoring each hose whenever I had to pull one of the guards off the frame. Even with only a few hundred hours on the machine it was almost a certainty to find a hose that already had braid showing. Just a very poor design IMO.
I think the parking brake release circuit runs on charge pump pressure <550 psi
Just wanted to follow up on the final (I hope) resolution on this problem. I installed the new hoses, so now all three hoses are new: the hose from the pump to the T and both hoses from the T to the left and right drive. I also temporarily installed another T and a hose that is attached to a pressure gauge outside the cab. I monitored the pressure for a couple hours of use and the pressure was always around 500 psi when the parking brake was released. It was interesting to see that the pressure drops to zero and the parking brake is engaged automatically every time the machine stops moving for more than a couple seconds. The brake is released and the pressure goes back to 500 psi immediately when you start moving. I still don't understand how both hoses from the T to the left and right drive could blow within hours of each other. One hose was blown in a spot out in the open that didn't appear to even be touching anything. The other hose was clearly worn where it goes through the cover plate. I'll just have to assume that the problem is fixed, but I'll periodically check all of the hoses going to the drives based on the advice posted by others on this thread. I appreciate all of the help and info.
On our 299D2 we wrapped the the hoses with a rubber backed carpet tile and punched holes in six spots to lace together with zip ties. Never had another issue with this.