Hydraulic Problems

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Your hydraulic system is the very heart of your Ferguson tractor. Mr Ferguson worked very hard for many years to perfect his 'Ferguson System'. It is the most ground-breaking invention in farming of all time. It deserves looking after. The safety of you your friends and family and visitors depend upon it. If have reason to be thinking about any additional form of depth control and you have a Ferguson "Tractor England" 20, you probably need to overhaul your hydraulics first. First let us examine the symptoms of faulty hydraulics.

Did I mention that what appears to be maladjustments, often turns out to be blunt equipment? Well that's the truth. If you attack your plough point with an angle grinder and turn the edges blue (or even straw coloured) you've broken it. Buy a new one. Once you have fixed that issue, it's time to have a look at the hydraulics.

Most of us will know about the problem of the sinking implement. We drive the tractor away with the plough or transport box lifted up, set off down the road and a few minutes later, it's dropped to the floor, digging an embarrassing groove in the Tarmac as we go. This is often caused by a leak somewhere in your tractors Ferguson System. We will look into where the leak may be.

Some of us will have a problem with a hydraulic system which just will not lift enough weight or lift quickly enough. This is often caused by worn parts. This wear is usually caused by dirt and dross in the hydraulic oil sump. Metal based dirt just grinds away all the working surfaces and makes more metal filings. It's self-perpetuating.

The final (or, should I say, the first), likely cause of difficulties is maladjusted settings. If the sensor spring is not set correctly, the implement will either dig in and stick in the soil, thus bringing the tractor to a halt ("Oh I need a more powerful tractor!") or will not drop properly, with the result that the implement will only just scrape the surface (Is the point sharp? Ed.). It is imperative that the spring and quadrant settings are correct.

A problem which is not necessarily caused be fault is when soil of uneven hardness/firmness leads to a cut on uneven depth. That is to say, when the implement hits a hard bit, the sensor thinks it has gone too deep and lifts the implement. Once up, it thinks "Oh! this is easy!" and drops. Result ... uneven ploughing. No mechanical or hydraulic fault!

Spring Setting First mount a plough or other heavy implement on your tractor. Grab the sensor spring in a fist and attempt to rotate it, with the plough on floor. If it will not, JUST turn (and it may well not move at all or it may bee FAR too slack), rotate , it is either stuck (maybe with rust) or too tight/too slack. Its should rotate freely no slack in it's end play. That is to say it should not be under compression but, should niether have any slack. If it or the rod which runs throughthe inside of it is rusty, clean the thing and apply penetrating anti-seize lubricant. If it is too tight/too slack, remove the top link pin from the implement, the hinge pin and the pin above that. This will release the top link union, which can be set aside. WITH GREAT CARE try to turn the spring adjuster with a short bar. If it will not turn, DO NOT FORCE IT. It will strip the thread on the thin shaft that connects it to the fork (inside the top cover) or BREAK (it's threaded on the inside and there's a thin rod connecting it to the fork inside) the fork assembly. If it is troublesome, apply heat and allow to cool repeatedly with LOTS of penetrating anti-seize lubricant along with a great deal of patience. These parts are NOT available new.

Quadrant setting First, we need to adjust the operating lever setting so that the lift-arms ALMOST begin to raise when the lever is 2 1/8" from the topmost position. This can be achieved by slackening the quadrant mounting bolts and adjusting it until the cam presses upon the fork inside the housing to the correct extent to achieve lift when the lever is in the correct position. With the engine running and the PTO engaged, and when the lever is 2 1/8" from the topmost position, a gentle 'heft' with two fingers at the plough's rear and the hydraulics should react to having pressure on the sensor and lift the plough.

Nasty little leaks Any leak which drips, even the smallest amount of oil, back into the pump sump or on the floor will result in the gear dropping. First check for any external leaks. The secret here is to clean your tractor of any oil and dirt, leaking oil can then be seen easily against Ferguson grey paint. The next obvious places that internal leaks can occur are in the top or bottom cover gaskets. These are under the seat (top cover) and under the tractor (bottom cover). Check the oil level is not overfull, remove the right hand side cover and start the tractor with your Tee Bar fitted (this will ensure maximum pressure and that the pressure relief valve is set off at by-pass pressure). With the PTO running and the quadrant in the 'Gear UP' position, look with a torch for any squirts or dribbles of oil from the top cover gasket or anywhere else. BE CAREFUL. DON'T PUT YOUR FINGERS OR TORCH IN THERE.

Removing the Seat Cover This is a nice little job! There is, however, no point to it except to replace the top cover gasket seal or to do work on the ram cylinder, ram seal (2 types, plain ring or gasket), ram piston or piston ring set. The author has known a ram cylinder to be broken and that results in failure of the hydraulic system and the oil passage between the main body and the top cover is dependant upon the gasket being in good condition. Leaks often occur as a result of failure of this gasket with the resultant, niggling, gear-drop mentioned earlier. You'll usually (but not always) see the oil squiring out when your get in there with your torch. A cracked cylinder is more awkward to see and, therefore more difficult to diagnose. We replaced all the gaskets before we found the broken casting on the 1st occasion we had this problem. "should've been more careful". The key is LOOK.

First remove the lift arms from the cover. There is a single bolt on each one with a large washer. Once the bolt is removed, the arm can be knocked off using a very large hammer very gently. The metals involved here are cast, and therefore surprisingly sensitive to shock.

Next, remove the quadrant (4 bolts) and auxiliary hydraulic spool valve if you have one. It may help to remove the seat itself. DO NOT loosen the 2 nuts which hold the piston cylinder in place.

It will be necessary to disconnect the wishbone which connects the control valve to the swinging fork inside. Remove the side cover plates. Study the pictures we have given here carefully. This wishbone is delicate. You really don't want to break it, trust me, I'm a doctor. Unbolt the spacer block from the fork (if you have one) and gently, but firmly reach in through the side cover holes to spread the fork and drop the wishbone out. Ensure that the control valve is fully inserted, the bottom cover may not come down if it's poking out, and it may well become damaged.

The ring of bolts round the edge can now be removed and the cover lifted. Once again, if the thing is stuck, use a large hammer VERY gently. Beware of the fork which extends down from the top cover to the control valve wishbone. You'd hate to chip the lip of the top cover or snap/bend the wishbone. NOTE the extra hole between the last and last-but-one bolts to the rear left side of the cover. This is the route that the hydraulic oil passes into the top cover on it's way to the ram.

Removing the Bottom Cover Before the bottom cover can be removed, drain the oil out of your hydraulic system and gearbox through the sump plug ( gasket here) into a suitable container. You will need to catch about 48 pints. Do make sure your container is a suitable size. It can be drained from the sump plug in the bottom cover. Once empty, place a bowl under the rear of the tractor (more oil will issue forth) and remove the PTO shaft. You will need to move the check chain brackets in order to do this. Once they are out of the way, unbolt the 4 retaining bolts and withdraw the PTO shaft. It may well be stiff to start with but will get easy after the first few inches. Then, GUSH! the oil flops out into your bucket or bowl and the shaft slides out easily.

It will be necessary to disconnect the wishbone which connects the operating valve to the swinging fork inside. Remove the side cover plates. Study the picture here carefully. This wishbone is delicate. You really don't want to break it, trust me, I'm a doctor. Unbolt the spacer block from the fork (if you have one) and gently, but firmly reach in through the side cover holes to spread the fork and drop the wishbone out. Ensure that the control valve is fully inserted, the bottom cover may not come down if it's poking out, and it may well become damaged.

If you have a hydraulic takeoff pipe, this will need to be removed next. Then you can unbolt the cover retaining bolts. Remember that your bottom cover is alloy and liable to crack if abused. Be gentle with it. It is wise to block up under the cover with something to prevent it falling when removing the last bolts. Don't let it hang at an angle on one bolt. Once the bottom cover is unbolted, you can lower the complete assembly whilst moving slightly to the rear and withdraw.

This is one of those moments when you realise that your tractor really did need this job doing. The entire pump is probably caked in goo and ooze. Clean the whole thing with a 3:1 ratio of paraffin and engine oil to prevent it going rusty if you need an overnight rest. You won't, of course, because this is the exciting bit.

Examine the hydraulic pump. There! I told you this was the exciting part. Before taking it apart, do examine the thing. See how it works. This is the absolute heart of your tractor. This is the part which makes the difference between a Ferguson tractor and all the rest. The PTO shaft is driven constantly from the gearbox, further forward, and turns the cam block. This in turn drives the 2 pairs of pistons right and left, in an out of the cylinder bores (in the valve chambers). The oil pumped in this way, is routed first through one and then the other valve assembly, keeping it moving in the same direction at all times. You will see the bypass (relief) valve, (which can be mounted in one of 2 positions depending upon the age of your tractor) and the control valve. The control valve performs 2 functions at the same time in all three positions.

1. Control valve position one:- In this position, the valve, which no doubt you are now slipping in and out of it's hole, allows the oil into the pump and thence up to the ram at the top, via the hole between the bolt holes round the edge of the bottom cover, up through the main casing and then through a similar hole between the bolts in the top cover, to the ram. It does not allow oil back from the ram, into the sump. When the ram is fully extended, and the lift arms fully raised, there is a by-pass hole in the ram cylinder. If the movement is prevented prior to the arms reaching the top position, the pressure relief valve is the only way excess pressure can be relieved. This little gem of a factor is absolutely key to the manner in which the loader and other external hydraulic equipment works, and the reason that such equipment cannot work without a Tee Bar.

2. Control valve position two:- will allow the oil to return to the sump from the ram so that the lift arms can drop, whilst, at the same time denying oil to the pump and creates a vacuum (or, rather, vortex). Be very aware of this dual functionality. We have heard it said that hydraulic engineers of the time told Mr Ferguson that this 'vortex' method of oil denial would not work. If they did, they were wrong.

3. In the third position, the control valve allows the ram to fall AND creates a circuit in which the oil does no work at all.

If the arms are prevented from rising whilst the valve is in the lift position (usually by the Tee Bar), the bypass valve allows the oil to divert back into the sump under full pressure. Oil can then be diverted to, say, a hydraulic loader ram or other external hydraulic equipment; another example is the Tipper Trailer ram.

The position of the control valve is governed by the fork. The fork is moved by the operating quadrant and/or the sensor from the top link. If the plough digs in, the rotating effect (around the axis of the Lift Arms) pushes up and forward on the top link, is gauged by the spring and pushes on the fork to move the valve into the LIFT position. As the plough lifts, the pressure comes off the top link and the plough can, once again fall. We have depth control !

The fit of the control valve is, therefore, most important. If it is not a perfect fit, it should be replaced.

OK, lets pull it apart

Gently remove the control valve. Whilst it is clean, give it a little wiggle. If it's in the slightest bit floppy, bin it and buy a new one.

Remove a valve chest. Just one for now. Examine the pump chamber gasket for leaks. That gasket stands between you and total hydraulic failure. If in doubt, replace it. See how the pistons fit into the holes in the cast iron chest? It's a delightful piece of engineering. Once again, one casting does 2 things. The nut on the top, holds 2 pairs of valve assemblies. There's lots of little bits in there. Don't open them yet. The pistons have to fit in the bores near-enough perfect. We'll see how to check this in a minute. Hold your fire. I know you want to pull the valve chest apart but hang on a minute and remove the other valve chest.

Now! see the way the pistons and cam and pto shaft bush fit in the casing? Make a note of the way they go back then remove the, cam block and pto shaft bush first. and lay them out. These bits are a very close fit. Fiddle around but do it gently. they come without forcing them. Now you can offer each piston up to it's respective bore, one at a time and check for a good fit. They don't have rings, just groves. That's OK. If they are slack and wiggle around at all, put them down the way they re-assemble and order replacements. there's no point in getting to this stage and putting back pistons and bores that don't fit.

But hold on a minute! Don't order yet! Take one valve chest, remove the bolt on top and remove the caps. These holes are full of little valve bits. They are very very important. They MUST go back the way they came out. Lay them out on a clean surface that will not be disturbed. Examine for wear. If worn, rounded and smooth or pitted, order replacements. Again, there is little point in ordering new valves if your valve chest is worn. Honestly, we've tried it. You might just as well replace the whole chest complete with valve parts. OK, I know you think I'm on a sales pitch, but this job is real pain to repeat if you find you have missed a leak. This advise is from experience.

Check the cam block and pto shaft bearing for wear by slipping them over the PTO shaft and seeing if they rattle. If they do, replace them. The newness wore off your tractor years ago or you wouldn't be doing this. There's no point in letting worn parts spoil the job. Have a look at the prices of the individual parts on our site and you'll see that we've discounted the "full kit". We've done that so that you can afford to do the job right. We've actually knocked £50.00 off, so do it.

Re-assembly The reverse of the above, making sure every part is exactly in the right order. Take special care over the wishbone and set the sensor spring and quadrant control with care. If you're new to this, you'll be amazed the difference that can make. Find a field and plough to your heart's content.

Replace the oil with NEW engine oil of the type you would use locally in an ordinary car. Even the cheapest modern multigrade oils are far better than any oil available at the time your tractor was made and are perfectly suitable.

Please dispose of you old oil at a proper disposal point. This old muck is terrribly harmful to humankind and to wildlife.

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