Power major hydraulics suddenly quit working

[scottyboy]

I was plowing some snow with my power major the other day and when i went to start it again to plow today it would lift up the blade. What are my options? They were very strong before never had any issues with them. Any help would be greatly appreciated. Anyone know what could be wrong? Hopefully nothing to serious.

[henk]

Just a hince. Have you had the major in the frost when cooling down? Could be condens frozen.

[scottyboy]

Yeah when i shut it off it was around -5 Fahrenheit. Ill have to try it when it warms up a little then. Thanks for the reply!

[scottyboy]

Had a lucky couple days and it warmed up and the hydraulics work again! Could it be because i forgot to let down the blade when i shut it off?

[henk]

Scottyboy,

Check the oil in the rear end with the oilstick to see if it is containing water.
I still think it's frozen condens in the hydraulic manifolt.

[oehrick]

Or if the oil is water emulsion-laden, ice throttling the pump suction?

[scottyboy]

Sorry been a while since ive been on. Got back to freezing and they quit working again. I find it strange that this is happening because i just changed on the rear end oils before winter. I kind of have a fear it might be the pump failing. I got them to work a little bit by letting the tractor run for around 30 minutes they didnt sound happy. Then quit working again. Oil looks pretty good dont see much if any water in it.

[shepp]

Just a thought, but when you changed the rear axle oil did you remove the plate on the bottom of the rear axle housing and thoroughly clean the wire mesh filter and magnetic filter? Presumably you used modern universal or super universal muligrade oil and not 90 gear oil, but if the filter is badly restricted then even with multigrade oil a slight thickening of the oil with a small temperature drop will prevent the pump sucking the oil in. Another possibility is that when you lift the linkage to full extent and the relief valve discharges at the top of the lift, the relief valve does not re-set until you lower the control lever. The valve might stick particularly if (as you said you did) you stop the tractor and leave the linkage up when you have finished if it is tarnished or there is some emulsified oil in it.

[henk]

the relief valve does not re-set until you lower the control lever.

A spring forces the lever to the nutral position, so then the relief valve should close again.
I'd first go for removing the valve block on the front of the cover. Remove the lever assembly. The front plate and check is any water is coming out. Worst thing you have to do when it's ok is making a new paper seal.
If that's ok, then second I go for removing the complete pedistalplate at the bottom of the rear end and check and clean the filter assembly. After removing the oil first off corse. It needs a new paper seal to.

[shepp]

Hello henk

The spring moves the lift lever back to the neutral position when the lever is released, this happens whether or not the relief valve has discharged. You can hold the lever in the raised position, it will not be forced out of your hand when the linkage reaches the top of it's travel and the relief valve opens.When the lever lowers to the neutral position then if it has discharged the relief valve re-sets and the feed to the lift cylinder and external tappings is sealed to maintain pressure in them.

Look at the posting "Major hydraulics 'click off 'when using log splitter " by dukeyfox on October 30 2016. He had constant problems with the relief valve discharging when using a log splitter with a seperate spool block coupled to the trailer pipe. The relief valve will not re-set until the lift lever is released from the lift position. He then had to move it again to the lift position and secure it, only for the same problem to arise on the next splitting if the relief valve had discharged.

Yes the relief valve should re-set when the lift lever is released if the spring is operational and returns the lever to hold, perhaps that is another factor to look at i.e. IS the spring operational? However it is a peculiar design of relief valve, it was modified and improved on the Power Major to reduce the tendency for it to discharge unecessarily and to improve it's performance, but a sticking relief valve is something else to consider. But my bet would be to go for the filter first!

[scottyboy]

I did not clean any wires meshes i just drained the oil out of the 2 or 3 plugs cant quite remember how many plugs. That might be the issue then. I did use Trans Hydraulic fluid. Is there a recommended oil to use in these? Ill have to try changing the fluid and that filter that you mentioned going to be a while Super cold where im at.

[shepp]

Hello scottyboy

I would say then that the wire mesh filter blocked is going to be the cause of all your problems! It needs very careful cleaning in petrol and blowing through with an air hose.

The recommended lubricant for the Power Major transmission AT THE TIME was an
HD30 grade oil, or a Universal Tractor Oil - this was replaced by a Super Universal Tractor Oil (SUTO), grades 10/30 or 15/40. However if you have used one of the current Universal Tractor Transmission Oils, which are probably a bit thinner than the SUTO oils, then I can't see any problems with this, as they are even more packed with anti-wear and wet brake and clutch additives (these latter not relevant to the Power Major!) than the SUTO oils. However if you put in plain hydraulic oil when changing the oil this is not correct, it will not adequately lubricate the transmission!

Drain the back end and keep the new oil you have put in if it is Universal Tractor Transmission Oil, and if it still looks clean and free of water or emulsifying then put it through a filter for re-use. If you had put in plain hydraulic oil then you will need to discard this and use the correct oil for the refill. Take off the plate under the rear axle (has one of the drain plugs in it) and remove and clean the wire mesh filter. Clean the magnetic filter which is attached to the end of one of the fixing bolts. Re-assemble and re-fill. Let us know how you get on.

[oehrick]

If you could find and fix up a pressure gauge to fit somewhere in the trailer-pipe line, it would allow you to see what (if any) pressure variations there are and what the actual pressures developed before and after the PRV sounds.

Given the low temperature aspect, the pump suction side still worries me.

[scottyboy]

I dont know of anyone with a pressure gauge ill have to keep an eye out for one. Just curious if the pump were to be bad are they normally rebuild or do you buy a new one?

[shepp]

At this stage leave the pressure test and relief valve and concentrate on removing the pump filter and thoroughly cleaning and re-assembling it with correct clean fluid in the rear axle, and see what improvement that brings. Pumps wear gradually over a period of time and their performance drops off slowly, they don't usually suddenly give up when it gets a bit colder when they have been working OK unless a seal ring blows or the aluminium casing cracks or the drive shears. You will be lucky to find a new pump, an overhaul using what parts can be scraped together or re-manufactured may be possible, alternatively a good used pump from a breaker.

But I still believe your problem is more obvious - a restricted filter which becomes more obvious when the oil thickens in cold weather!

[oehrick]

At this stage leave the pressure test and relief valve and concentrate on removing the pump filter and thoroughly cleaning and re-assembling it with correct clean fluid in the rear axle, and see what improvement that brings. Pumps wear gradually over a period of time and their performance drops off slowly, they don't usually suddenly give up when it gets a bit colder when they have been working OK [CUT]

But I still believe your problem is more obvious - a restricted filter which becomes more obvious when the oil thickens in cold weather!

As shepp says, don't worry about pump failure at this point, check out and clean the suction side filter first.

[shepp]

scottyboy

I called in on a friend this afternoon who has been replacing the twin seals in the PTO drive unit of his Major with a bit of advice from myself, and I told him a few days ago that before he re-filled the back end with new oil he should take out the suction filter for the hydraulic pump and give it a thorough clean. It takes a bit of time because it is better to drop the drawbar frame to get to the housing which is held by four bolts, this is why it gets deliberately overlooked when people change the rear end oil, but boy is he glad he took my advice!

The hydraulics on this tractor were still working, but when he got the filter out it was just a mass of emulsified oil and muck, he could barely see any metal! He has had to scrub it in petrol with a soft wire brush 5 or 6 times and wash it with a high pressure hot water washer before blowing it clean with an air hose.

Hopefully your filter might not be as bad, but if you live in a cold climate then everything is pointing to this filter as the cause of your problem!

[scottyboy]

Alright thanks guys ill do that when i get a chance. I appreciate all the help!

[scottyboy]

Hey guys quick question do i have to drain both of the plugs or just the one under the filter?

[shepp]

The large plug under the filter housing plate drains the rear axle centre housing which contains the hydraulic pump and final drives. The refill plug is located in the hydraulic lift cover and the dipstick for the rear axle housing oil level is near the gear lever.

The drain plug in the PTO unit under the gearbox, which is a smaller plug, drains the main gearbox and PTO drive unit. The refill for the gearbox and PTO unit is the large plug on the circular plate on the side of the gearbox just in front of the clutch pedal. The correct level is to the bottom of the opening when this plug is removed, it is marked on the lug cast into the circular plate.

The rear axle centre housing (containing the hydraulics and final drives) and the gearbox/PTO unit are separately lubricated and there are internal oil seals between the centre housing and the gearbox/PTO unit to prevent transfer of oil from one to the other, this is because the oil level in the gearbox/PTO unit is higher than the oil level in the rear axle centre housing - were you aware of this? The two need to be separately serviced with regard to checking oil levels or changing oils.

The answer to your question is that to clean the pump filter you need only remove the drain plug under the filter (assuming that the oil seals between the gearbox and rear axle centre housing are intact and sealing!). After re-filling the rear axle check the gearbox oil level and add as necessary.

[scottyboy]

Alright thank you. i drained both plugs the first time i did it and refilled each of them just wasn't sure why is had separate plugs good to know. Looks like some good weather to be able to do it in the next few days!

[scottyboy]

Changed the oil and cleaned the filer still dont work. Anyone got any ideas? Kinda thinking about selling the tractor.

[shepp]

Mmmm...., it's a pity that the most obvious cause of the fault is not the one.
There are a number of possible causes.
Firstly, check that the PTO shaft is still turning when you move the hydraulic lever to lift, to eliminate anything completely obscure like the PTO section of a livedrive clutch slipping under load. Check that the hydraulic arms can be moved manually up and down and are not jammed in some way. With the engine running slowly listen close to the control valve block for the sound of any oil movement or noise from the relief valve when you lift the control lever.

I would then look at the relief valve. The control valve block is bolted to the front of the lift cover under the seat, the control lever goes into the right hand side of it. On top of the block, to the left if you are sat in the seat, there is a plate held with bolts. Under this is the pressure relief valve. Thoroughly clean the whole area round the plate, then undo the bolts progressively a couple of turns each until the pressure on the plate from the relief valve spring is relieved. Remove the plate and bolts. You will then see the top of the relief valve spring guide. If yours is an early Power Major you might see a square nut type guide which is an adjuster for the pressure setting, if a later tractor you will see a circular top to the relief valve spring guide. You need to remove the valve complete with spring from the housing. There is the top (circular or square) spring guide section, then a shim pack (careful!) ,then the spring , then the valve body itself which is conical shaped at the bottom, BUT BE VERY VERY CAREFUL! - under the bottom of the tip of the valve body there is a steel ball, this might come out with the valve body if it is stuck to the tip of it so do not lose it! If it does not come out with the body remove it with a magnet from the control valve block. This ball makes the pressure seal between the tip of the valve body and the seat in the control block.
Clean everything off and check the spring is not broken. Check the valve is not scored badly, lightly clean it up with fine oiled emery cloth if necessary for it to be able slide in the bore freely, check the ball is not damaged.
If you have the relief valve with the square head spring guide under the plate, this type was known sometimes to stick - what would happen was that the valve would open quickly and the valve body would rise too far against the spring pressure allowing the steel ball to be pushed up the side of the conical tip of the valve body thus jamming it open when the control lever was released to hold or drop. This could be your problem, especially if everything is dirty or emulsified. The later valve with the circular top spring guide had a lift restrictor stop in it to prevent the valve from opening too far and the ball becoming dislodged and stuck, jamming the valve open.
Check everything for damage, thoroughly clean all components and the seat in the valve block. Stick the ball to the tip of the valve with heavy grease and carefully slide the valve back into the valve block. Re-assemble everything in the reverse order of removal - the spring, shims and adjuster type spring guide or circular top type spring guide, the cover plate, and see if the hydraulics work. Post the results and if it's no joy then there are quite a number of other things which can be checked, but let's eliminate the relief valve first.

The fact that the hydraulics did start to work when it became warmer before stopping again suggests that the problem ought to be minor but obscure.

Good luck!

[scottyboy]

It got really warm today and it started working again. Any ideas its almost as if the hydraulics are freezing up. Hydraulics are as strong as they were during the summer.

[shepp]

Hi scottyboy

As I said in my last post, your problem is likely to be minor but obscure.
The hydraulic system might simply have been airlocked after the cleaning of the filter and re-filling the oil. The increase in temperature might have allowed the oil to thin a bit so that the pump was able to draw it up. It is unlikely but possible, time will tell.

If it stops again, then how dirty was the mesh filter and the transmission case when you cleaned it? This will give an indication of how likely there is to be muck in the control valve block.

The system is very simple. A vertical steel pressure pipe with an "O" ring on each end brings oil up from the pump into the hydraulic top cover housing. A horizontal steel pressure pipe with an "O" ring on each end brings oil under pressure from the top cover housing into the control valve body bolted to the front of the top cover. An outlet from the control valve body takes oil under pressure to the lift cylinder with an "O" ring between the body and the lift cylinder.
In the control valve body there are 3 valves. One is the spool valve that does the actual diversion of oil flow to lift, to hold and to drop. This is attached to the control lever by a mechanical linkage so it should not be possible for this to stick intermittently and cause problems - but you never know! Another valve is the pressure relief valve which I have described in my last posting. The third valve is the check control valve which is located in the bottom of the control valve housing, to get to this you have to remove the control valve housing off the lift cover.
If it stops lifting again then your problem MUST be in the control valve body. either the pressure relief valve sticking, or the check control valve sticking, or ( unlikely) a problem with the spool valve. These may be caused by dirt, or the valves might have acquired a wear ridge due to extensive use, in which case you will have to clean
them up carefully with fine grade oiled emery cloth.

But there is nothing there that cannot be easily sorted! If you get one of the workshop manuals, such as the I & T one ( not expensive), you will understand the system better.

Regards.