94' Case 1845C drive problems, please help

[melben]

What kind of abuse do you think that machine should stand?????? I have seen external abuse cause broken chassis in the axle housing areas, I have seen bent cylinder rods, belt loader frames, just about any damage that abuse can cause. Let's see what actually caused your problem and then assess the situation, could be something entirely unrelated to dirt that coincidentally happened. Hydrostatic systems are some of the toughest drives on the planet and are being used in very large crawlers of very high horsepower. Most brands of equipment use systems built by one or two major manufacturers and their designs are so similar as to be indestinguishable. Your machine ran years till the hose failure. What you are looking at as a toothpick is a really well designed and implemented technology that has proven itself in millions of units with systems just like yours. I am not going to pass judgment till we find out if abrasives actually destroyed your pump, but if so that would be akin to dumping sand into a transmission or into an engine that did not have a filter and complaining about the poor design when certain failure occoured. The system is fine as designed and adding filters would be fruitless, as I previously stated if that abrasive material moves through those finely machined precision areas one time, the damage is done instantaneously.

 

[maytag]

bi-directional filter

There are filter assemblies available for this application(6000psi/100gpm)don't know whether you have room.

Maytag

 

[cldunivan]

I understang the situation. i was just saying that off all the metals in the world, diffrent alloys and such, why pick brass parts to be the heart of the machine. Brass is soft and scares easily i know. why not build the pump out of hardened steel or iron. some type of chrome moly of something. You can get by with alot of small debris in engines. the oil pump can take alot because its made of hardened steel or iron. its still precision made but they can take some abuse before it totally fails. I know its a good system when working but you would atleast think the fluid would be filtered contionously. just my thoughts..... you guys have alot of knowledge here and are really helpful. im looking forward to what actually caused this thing to mess up

 

[maytag]

All parts are supposed to be riding on a film of oil-as far as something other than brass-check out "Oilgear" brand pumps and motors-they are built out of steel components.

Maytag

 

[melben]

If I seem to be getting a bit out of sorts on these recent posts I'm sorry. We are a Case dealer and I have worked for the same dealer in service since 1962 when I graduated high school. I was there before Case used Hydrostats and grew up with them, The latest Case crawlers use the system in high HP extreme duty applications. I am quite sure that if there was a more satisfactory tougher way to do it reliably the pump manufacturer would do it You seem to be demeaning what I and others who are advising you KNOW to be a very fine system. Those units with the brass comutator plates will generally run many thousand hours with no significant wear under normal conditions. In a hydrostat pump you have a block and piston assembly that turns with the end running against the brass comutator plate that directs the f/r oil flow through slots in the comutator plate depending on which way the swash plate is tipped. There is a slight spring load to seat the b and p against the brass plate. the brass plate serves as a bearing, putting two ferrous materials together at that position could cause some serious challenges as to keeping similar metals from galling. As peviously stated, there is absolutely nothing wrong with this setup and if our advice is followed after repairs are made you will have many years of satisfactory service. Please do not cut corners, I hate to be redundant but every foreign particle must be removed from the system. Mel

 

[cldunivan]

I know these systems are reliable. im not questioning that. however with every moving part in the pumps and drive motors there is always going to be some type of wear and that means particles. why not have this system contiously filtered? If they would build it like that the lifespan, even though great now could be a whole lot better. But yes i am going overboard with the cleaning. everything is getting drained and flushed and all new fluids and filter. this is the last time i want to go threw this

 

[willie59]

hi cldunivan, I'm in agreement with melben that these are very well designed and reliable hydraulic systems. You ask the question as to why the systems are not continuously filtered, when in fact they are. There is a filter in the closed loop system. What is not filtered continuously is the oil going from the bi-directional drive pumps to the drive motors, for a number of reasons. It would be expensive to do that making the benefits not outweigh the installation and service costs, it would be difficult to do as the oil moves both directions through the hoses going to drive motors, filtering output oil from a pump always increases the risk to the pump from a clogged filter (for whatever reason it gets clogged), and that it's really not necessary as there is a low pressure return filter in the oil cooling circuit. You have to have a basic understanding of how the closed loop system works. Oil from the reservoir feeds work equipment pump and the charge pump for the drive pumps. To keep this simple, we'll leave the work equipment circuit out of this discussion for the moment and focus on the drive circuit. The charge pump pressurizes the internal housing of the drive pumps. If your not driving the machine, swash plates are in the null position, no oil is being delivered to the drive motors. Oil being delivered from the charge pump leaves the case drain of the drive pumps and enters the cooling circuit to be cooled and filtered, then returns back to the line coming from the reservoir to feed the charge pump once again. Hence, filtered oil. When you began moving the machine, oil in the housing from the charge pump is delivered to the drive motors via the drive pumps. The charge pump delivers more oil than is needed by the drive pumps so there is always some flow out of drive pump case drain. This prevents cavitation of the pumps. And it also benifits the filtering of the oil from the drive circuit. When you deliver oil from the pumps to the drive motors, after it's done its work in the motors, the oil returns to the drive pump to be mixed with the filtered oil from the charge pump. Yes, some of that oil will enter back into the drive circuit, but some will exit the case drain to be filtered. The point is, the oil in the drive circuit is not isolated from the rest of the machine systems, including cooling and filtering. It's always being mixed with cooled and filtered oil. So you can see there is really no need for expensive and cumbersome filtering systems for the drive system as the oil that operates the entire machines system is being filtered continuously in the cooling circuit.

LoL, alrman will probably now rib me for writing another novel.

 

[maytag]

green hydro

You have been given some very good info-in addition the hydrostatic drive is by far the most energy efficient hydraulic system. Regarding the filtration,
bi-directional filtration is done everyday in heavy industry and regardless what some one tells you a filter is certainly cheaper than a pump or motor-not to mention downtime.
Also never seen a filter cause risk or harm to a pump unless it is on the suction side and you put a light check valve in parallel with the strainer(filter)
to avoid the risk of cavitation. Pressure filters(at least the ones I use)all have a bypass(light check valve)in parallel with the elements also.

Good luck,

Maytag

 

[melben]

Atco has done a great job of explaining the Hydrostat system. In addition the main hydraulic oil returns to sump through a fine micron filter so the total system capacity is being filtered more than two times a minute assuming a 15 GPM pump. There is little to no wear in a rotating group that is properly maintained. If one is concerned about the miniscule amount of material that is shed from the rotating group under normal operation they need only to disassemble a unit that has worked flawlessly for years to see their fears unfounded. In fact, I would venture to say that the "wearing in" process as the B&P assembly takes a fit to the commutator plate actually improves the effeciency of the tandem pumps. The confined spaces required to build a compact skid steer do not allow the space for a filtering system and as Atco so aptly pointed out, if any debris were collected as in a normal filter element going forward, it would be washed back out when you reversed the oil flow unless a complicated system was incorporated increasing the complexity of the closed loop system. If the system is properly maintained and no catastropic failure occours there is no significant wear over the lifetime of the units. The brass commutator plates being condemmed will not have enough wear that you can feel or measure after years of faithful service and can be and usually are put right back into service. You need to actually understand how the system works to make assumptions as to what will improve its life. Unless a failure occours for some reason there is nothing for a filter to catch, this is proven by inspecting units that have many thousands of hours use on them and if a internal failure does happen an inline filter will not help anyway, you'll be tearing it down. To those of us who know and love these machines which are some of the toughest and well built in the industry it is amazing to see this much discussion about an issue that is a nonissue. Some of us actually have hands on and have been eyewitnesses to the extremely long life of a properly maintained unit and the total destruction of one that has been destroyed by an unfortunate failure of a component within the closed loop system or contamination introduced into the system from an outside source.

 

[willie59]

Hi maytag, I didn't say high pressure downstream filtration couldn't be done, I was only making the point that it isn't really necessary on these machines for various reasons.

 

[maytag]

filtration

Atco,

Interesting discussion-funny how people from different backgrounds approach a problem/overcome obstacles. I started out in the mobile world but moved into heavy industry after a few years. We focus on machine reliability and overall equipment efficiency as more tons of quality steel out the door means more money for both company and workers alike. Monthly oil samples are taken and sent to a lab where cleanliness and chemistry are verified-we try to maintain an ISO 13/10 cleanliness level for our hydraulic systems-this requires a lot of filtration and good housekeeping. All pumps have pressure filters, all systems have both return filters and a kidney or polishing loop.
I'll be the first to admit its a lot easier to do these things in an industrial setting rather than a piece of mobile equipment.

Have a nice weekend,
Maytag

 

[willie59]

Yes, maytag, the differences between mobile hydraulics and industrial is night and day. You could have an industrial process unit that cost $20,000 or half a million dollars. It would be a machine that once it's installed and operating, if it were to go down because of poor maintenance or poor design, it could affect from one worker to a dozen workers on the process line, not to mention the loss of production for that unit. If a skid loader goes down, the job boss would simply move the workers to do something else until the unit is repaired, or, bring in a rental unit. Kinda hard to bring in a rental 500 ton press to a production plant. Also is the differences in purchasing the machines. Let's say you need a certain press, you find one built to suit your needs, oh no...it cost $150,000! No, we'll just go down the street to "press r us" and get one cheaper. LoL...no, it doesn't work that way. Industrial equipment is an investment that it's necessary to maintain properly for maximum output and production. In the skidsteer world, a manufacturer could build the most top of the line machine with all the cutting edge technology and components that would make the machine last near forever...but they would never be able to sell it. The increased selling cost for all the goodies would not make it price competitive with other brands. That's not to say less than perfect machines are the objective, its just purchase price for the consumer does play a big role in how mobile machines are built. Fortunately, the brands do want their machines to be reliable, no manufacturer wants there brand name to be a cheap piece of junk, so pretty much all the brands use qaulity components and designs that are sufficient to give years of reliable service at a minimal cost with proper service and manitanence.

 

[cldunivan]

Wow. Its amazing how much discussion this has stirred up. Looks like you people know a ton on this stuff. I have already learned alot from you all. thanks. as far as my problem goes, i am still waiting to hear back from the shop. i may give them a call on monday, just to see whats up. I have cleaned up the whole machine, got it all power washed and dirt/oil free. it was messy and alot of work but should pay off. next on the list is to drain all the fluids and service the whole machine while its tore down and clean. I took the other drive hoses off to clean them up and inspect and the other 3 old one's have a couple spots where the metal has already been cut through a couple layers so im ordering new hoses for them, another 300 bucks but atleast i know they will be good and everything up to par. I will keep you all posted on what i find out with the pump. :usa

 

[junebug1313]

the pump

Wow. Its amazing how much discussion this has stirred up. Looks like you people know a ton on this stuff. I have already learned alot from you all. thanks. as far as my problem goes, i am still waiting to hear back from the shop. i may give them a call on monday, just to see whats up. I have cleaned up the whole machine, got it all power washed and dirt/oil free. it was messy and alot of work but should pay off. next on the list is to drain all the fluids and service the whole machine while its tore down and clean. I took the other drive hoses off to clean them up and inspect and the other 3 old one's have a couple spots where the metal has already been cut through a couple layers so im ordering new hoses for them, another 300 bucks but atleast i know they will be good and everything up to par. I will keep you all posted on what i find out with the pump. :usa

did your machine ever bog down when moving or pushing a load?

 

[mustang960]

Cl I'm feel for you, wow that really sucks, but this has me thinking...and rather scared. I've owned my skidsteer for all of 4 days now and what about plugging in attachments? Good Grief, all the attachments which came with this thing have fittings covered in grease and dirt, and when I tried out the grapple bucket, I wiped the male clean but what about the female on the skid steer itself? I havent really played with the machine yet, could I have already introduced contanimates?

 

[cldunivan]

no the machine never bogged down much unless digging straight into a mountain of dirt. then is was just a little. Where i stand now is that the Case dealer i took the pump to said they couldn't find enough damage to cause the problem i was having. well im no idiot and i know its in the pump. I picked it up in pieces and have the pump back home now. i plan on polishing the brass plate and parts all back smooth and flat and reasseble it myself and see what happens............ wish me luck

 

[maytag]

Mustang,

Yes dirty quick disconnects is an avenue for contamination into the system, another is adding unfiltered oil (most new oil is not clean enough). If your hydraulic tank is vented to atmosphere make sure you keep the breather clean-there are options for a breather and moisture removal both.

Maytag

 

[mustang960]

Its all good info, thanks.

 

[Z2898]

CL,

Read your first post. I have 1 question, hopefully you will humor me by checking.

The new hose that you replaced--does it have the same inside diameter as the original? If so do the hose fittings also have the same diameter? Sounds like one or the other is smaller in diameter creating a restrictive spot. This could be the reason the problem followed you to the other side. It could also explain the slow response. (If you have flow across an orifice you will have a pressure drop) I could be way off. Hope to hear back from you.

Good Luck!

 

[lost in france]

Anyone use a rechargeable aerosol to clean hydraulic connections whilst out in the field changing implements,Is this a good idea,and do these things work
(I found the eastwood billet whilst surfing the net):Banghead