Maintenance comment / question

[SnowRidge]

There is an additional issue with the hydraulic filter mounted on the supply side. A dirty filter will reduce flow and can result in significant negative pressure (vacuum) on the intake side of the charge pump. If the charge pump does not receive adequate oil supply cavitation in the pump can occur with resulting damage. My opinion is that the potential for cavitation with a filter mounted on the intake side is the reason for the very frequent change interval specified by PT.

Bob has hit the nail on the head regarding the 50 hour intervals specified for the hydraulic filter.

Diesel fuel filters are frequently changed when there is no need. Racor and other manufacturer's offer vacuum gauges to indicate when the filter needs changing. I installed a generic vacuum gauge on my diesel engined boat, along with a fresh filter. I never changed the filter again.

 

[Wayne County Hose]

Either you or Casey need to go back to school on hydraulics. What he is actually saying is that if your tank is clean, you really don't need an input filter, but everyone knows, it is sometimes difficult to keep water and other contaminants out. Power Tracs hydraulic driven machines like WOODLANDFARMS and I and a bunch of others own , use a combination closed loop and open loop system. The drive system is closed loop system with a 10 micron filter on the input to the charge pump on the variable speed hydraulic pump, and is the only filter in the hydraulic system , the PTO and the steering uses gear pumps , all three pumps sharing a common reservoir. All the filtering for the complete system is the fluid going through the charge pump, which is a makeup pump, IE, making up the difference in the fluid lost through the drive motors via the case drains, and the case drains on the VSP pump..

Replace 20 gal hydraulic oil yearly, you got to be kidding, although it would be good for your business. Regular motor oil, at $3.00, would cost us $240.00 If you uses synthetic oils, at $6.00 a quart, the cost would be $480.00

On the subject of input filters, I think that I agree with him on the damage to the pump caused by suction restrictions caused by clogged up filters. Personally, I think each circuit should have it's own filter with alarms to indicate replacement. I think I would depend on an oil test to determine when to replace oil. The external filter units would also be a good idea on a weekly basis. Good tank filters are a must. Clean fluid with the right chemistry is the only way to get the longevity that we paid for. I don't know how long you have been in the hydraulic business, but common sense with a little knowledge goes a long way. By the way, do you own, and use any piece of hydraulic equipment? Do you actually go out to someones broke down hydraulic machine and diagnose the problem and fix it? Are you a salesman or a hydraulic technician/engineer?

Hmm, no need for me to post my resume here. I don't need to justify my schooling or experience to anyone. I guess I don't know anything about this stuff. Just ask all the people here that I have helped. There's no need to get personal or attack anyone about this stuff. I know exactly what Casey said about a suction strainer. Sure, if a tank is clean, you don't need one. Now show me a tank out in the real world that is clean enough to not need a suction strainer.

Almost every major equipment manufacturer I can think of in my experience recommends changing out hydraulic oil by hours or every year, whichever comes first.

 

[ponytug]

Hours or time is a great way to ensure that the oil chemistry is not depleted. Analyzing oil will enable one to do a better service job, by;
a) Ensuring that the oil is still on spec
b) Detecting failures in the machinery via particle or elemental analysis.

Since it is hard for most people to stomach the cost of regular oil analysis, most manufacturers and users just go by miles/hours. Is it optimal? Of course not. Is it a sensible cost/benefit result? For most users, yes. For heavy equipment operators, people with large oil usages, analysis pays for itself pretty quickly. So, my takeaway is that it depends.

If you analyze the oil every XX hours at $30 a pop it adds up. Whether it adds up to more than the oil changes.... I would suggest that it depends on usage, part failures, Murphy.

Is there even a recommended service interval on the PT hydraulic oil? My manual just says change it when discolored or contaminated, which are pretty gross indicators of oil depletion.

Keep up the great advice WCH. We certainly benefit. Can you suggest particular vents? The vent on my tank is a multi-layer foam. One problem that the PTs have in general, is that there is an obstruction issue with the seat being very close to the tank lid, so that many higher profile water/low micron caps don't fit.

WCH: I'm with you on the cleanliness of tanks in the real world. Perhaps on a medical device line in a clean room you could get away without one, but why take the chance? Anywhere else, forget.

I am always impressed with the ability of users to screw up. Like the technician that used a brass regulator on an HCl gas line on Firday at a semiconductor plant, and went home for the weekend. By Saturday night, it had eaten its way through the regulator. By Sunday morning, it had dissolved in the ultra clean water. By Monday morning, every gas line, every piece of equipment that used water was corroded out. The entire plant was shut down for six months while it was rebuilt. Frankly, I'm impressed that it only took six months.

I think that the internet has a tendency to allow people with statistically uncommon points of view to air them. For neophytes like me, the problem is sorting the wheat from the chaff.

J.J. I think that we all agree that the hydraulic oil on the PT could be better handled; you and others have made useful modifications, via additional filters and external filtering that I am sure improve the quality of your oil. Just because a service is expensive, doesn't mean that you shouldn't do it. I used to drive a car that the clutch replacement required pulling the engine. Sure, the clutch was only $65, but the labor... Like with oil, you can change the clutch on a mileage basis, or you can change it when it is showing signs of failure. In the case of hydraulic oil, signs of failure might be rather pricey, as it is likely to be system wide wear due to poor oil.

I think the bottom line is "yous paysa your money, and yous takesa your choice." What one person deems prudent might seem like overkill to another, and vice versa. Just because I had one car that I drove 200000 miles on one clutch doesn't mean that I think that ought to have been the manufacturers recommended service interval. I just thought that the downside to changing a clutch too late-worn thrust bearing- was minimal, and I was willing to wait until a problem showed up. But that is just my opinion. Oh, and I am sure that I got lucky. The prior owner only made it 70,000 miles on the first clutch.

All the best,

Peter

 

[J_J]

Hmm, no need for me to post my resume here. I don't need to justify my schooling or experience to anyone. I guess I don't know anything about this stuff. Just ask all the people here that I have helped. There's no need to get personal or attack anyone about this stuff. I know exactly what Casey said about a suction strainer. Sure, if a tank is clean, you don't need one. Now show me a tank out in the real world that is clean enough to not need a suction strainer.

Almost every major equipment manufacturer I can think of in my experience recommends changing out hydraulic oil by hours or every year, whichever comes first.

Those questions were simple questions, and I was hoping you would answer at least some of them. I don't want your resume. If you have been working with hydraulics for 20 or 30 years, that would tell me something. If you went to an engineering school, that would be a big plus. If you learned it on your own, then I commend you . I think people in general would like to know those things. I wasn't trying to attack you or offend you in any way. You probably have helped many people here and other places, I have learned a thing or two from you. I don't live with hydraulics every day, nor do I want to. I am just an old timer, learning more as time goes by. If you have the knowledge, put it out, but don't assume that everybody else is wrong. There are some smart people on here.

 

[J_J]

I am going to make a rough guess that only about 10 % of the people that own tractors or anything using hydraulic fluids change out and flush their systems. How long does the ATF stay in the automobile before being changed. Some never. I have heard it said that the fluid never wears out, but the additives do, and the rest get contaminated in some way or another. So let us use some common sense here. Where do the contaminants come from. Wear and tear on moving metal parts, rubber breaking down, water getting in the system through condensation, overheating. Return line filtering would not let things from that circuit get in the tank., therefore a clean tank, and assuming that we have a good tank breather cap. I believe in suction filters, that is what the PT uses for total filtering, but if it clogs up and starves that $1500.00 VSP pump. You just ruined that day for sure. So what do you do about it. Get a filter with a change indicator on it. My PT is an early 90's model, and has been working good so far. The pumps that had to be changed, were the ones not directly filtered. Rules are rules, and you know we all follow rules. Not.

 

[SnowRidge]

Hydraulic filters for the PT-425 are not too expensive, if you don't order from Tazewell. Like a lot of owners, I use a Wix 51551, also sold as a Napa 1551. I picked one up at the Napa store today. It was $11 and change, including 9% tax. I can get them a lot cheaper with a $50 minimum order from Filter1, when I remember to order in time.

Cheap insurance, IMHO.

 

[MossRoad]

Almost every major equipment manufacturer I can think of in my experience recommends changing out hydraulic oil by hours or every year, whichever comes first.

The problem is, most of us do not put that many hours a year on our machines. An annual oil change would cost me $120.00 minimum plus I would have to dispose of 10 gallons of oil. I look at it and it is nice an clean. I add a quart to it every 50 hours when I change my hydraulic filter. I think, as long as I keep the connectors clean, the filter changed and the filler area clean, I should be good for a decade or more.

 

[Wayne County Hose]

Oils are the most misunderstood part of any machine. You can't see it wear out so you still think it's okay. Now if you don't put many hours on a machine, it may be okay to let the fluid go a couple or three years. But a decade? Now you're talking a crap shoot. Sure, I know of machines that used the same hydraulic oil and filter for a decade and had no issues. But the law of averages were not in their favor. I used to know women that looked nice and clean too. But, you wouldn't want to touch them.

Okay, my experience and schooling. 2 year electronics degree, 22 years as a forklift with my specialty in electro-mechanical hydraulic systems. I have at least 15 one week schools at factory training centers. I won the Top Gun award at the school for the most technologically advanced forklift made. I even scored higher than the factory rep I was supposed to call for technical help. About 6 years as a field service foreman, a couple years as a service manager for a forklift dealership and 2 years as a maintenance manager for a large warehouse. I've owned my own hose and hydraulic shop part time for the last 8 years and fulltime for the past 20 months. I am the premiere shop in the county, bar none. My shop is a Weatherhead Affiliate Distributor and a sub-dealer for Cleveland Brothers Caterpillar. When the big boys around here have a problem, they call me. I have yet to have a cylinder that I worked on come back with a problem. When my competition screws something up, it always ends up in my shop and that's where the problems end. When the crane for the largest construction company in NEPA had a hydraulic problem, they called me to troubleshoot it and I nailed it within a half hour. My customers will drive past at least 5 other shops to come to mine and that is not an exaggeration, that is fact. I usually get the tractors in my shop that the local dealers couldn't diagnose, hydraulically speaking. I haven't had one in my shop yet that I couldn't diagnose rather quickly. So I would guess that I am qualified to answer the questions that I do answer. No, I am not always right and I do openly admit when I am wrong. Much of what is discussed here are opinions and many times, there is not a correct one, but some more correct than others. When I do anything, I try to make it as if I was never there, like the machine never needed a repair in the first place. That to me is the ultimate compliment a mechanic can be given, when a customer tells me that it runs like or better than it came from the factory.

To me, someone that has a degree doesn't impress me. I have proven more engineers wrong in my career than I can count. I have also known some great ones. You can send them to school, but you can't make them think.

 

[aczlan]

You can send them to school, but you can't make them think.

aint that the truth, no matter what the profession or the school. some people can test well, have a 4.0 GPA but cant "pour water out of a boot that has the directions written on the heel". they are great as long as they can follow the script they ave memorized but once they get beyond that script, they flounder about and are worse than useless.

Aaron Z

 

[J_J]

Oils are the most misunderstood part of any machine. You can't see it wear out so you still think it's okay. Now if you don't put many hours on a machine, it may be okay to let the fluid go a couple or three years. But a decade? Now you're talking a crap shoot. Sure, I know of machines that used the same hydraulic oil and filter for a decade and had no issues. But the law of averages were not in their favor. I used to know women that looked nice and clean too. But, you wouldn't want to touch them.

Okay, my experience and schooling. 2 year electronics degree, 22 years as a forklift with my specialty in electro-mechanical hydraulic systems. I have at least 15 one week schools at factory training centers. I won the Top Gun award at the school for the most technologically advanced forklift made. I even scored higher than the factory rep I was supposed to call for technical help. About 6 years as a field service foreman, a couple years as a service manager for a forklift dealership and 2 years as a maintenance manager for a large warehouse. I've owned my own hose and hydraulic shop part time for the last 8 years and fulltime for the past 20 months. I am the premiere shop in the county, bar none. My shop is a Weatherhead Affiliate Distributor and a sub-dealer for Cleveland Brothers Caterpillar. When the big boys around here have a problem, they call me. I have yet to have a cylinder that I worked on come back with a problem. When my competition screws something up, it always ends up in my shop and that's where the problems end. When the crane for the largest construction company in NEPA had a hydraulic problem, they called me to troubleshoot it and I nailed it within a half hour. My customers will drive past at least 5 other shops to come to mine and that is not an exaggeration, that is fact. I usually get the tractors in my shop that the local dealers couldn't diagnose, hydraulically speaking. I haven't had one in my shop yet that I couldn't diagnose rather quickly. So I would guess that I am qualified to answer the questions that I do answer. No, I am not always right and I do openly admit when I am wrong. Much of what is discussed here are opinions and many times, there is not a correct one, but some more correct than others. When I do anything, I try to make it as if I was never there, like the machine never needed a repair in the first place. That to me is the ultimate compliment a mechanic can be given, when a customer tells me that it runs like or better than it came from the factory.

To me, someone that has a degree doesn't impress me. I have proven more engineers wrong in my career than I can count. I have also known some great ones. You can send them to school, but you can't make them think.

Thanks, At least now, I/we know where you are coming from.