Rear pto shaft size

[Robhar]

Hi everyone!!! I am new to the forum and to the tractor world so I apologize if I ask any questions that seem like they should be common sense. I have a fordson power major I bought 2 years ago equipped with a Sherman f8 backhoe and a Wagner w7 front loader. The backhoe has its own hydraulic pump and there is a separate pump in the front for the loader. The pump for the backhoe went bad. If anyone could tell me a replacement pump for this setup I would greatly appreciate it or if anyone can tell me the size of rear pto shaft and number of splines I would appreciate it. It looks like the only way to get to this disaster is to rip the whole backhoe off which seems like a very big task. The current pump is somewhat accessible but it is bolted to a gear box that is some how attached to rear pto. The gear box and rear pto are not very accessible.

[blackbob]

Hello Robhar, welcome to the forum!

Some photos of your pto/pump arrangement would be helpful.. But in the meantime, have a look through Mark's excellent selection of photos, https://drive.google.com/drive/folders/ ... KuMr5mX8YJ particularly the one showing the back of the tractor.. does the gearbox you mention, have a similar long selector lever reaching up towards the right side of the seat? If so, this gearbox is part of the tractor and not readily removable; and the pump will be attached to the output shaft of this gearbox.

Otherwise the whole gearbox should be fairly easy to remove. Have a look at the photo in this listing: https://www.ebay.co.uk/itm/PTO-YOKE-QR- ... SwScJa9FN2 you can see that it is splined at the right-hand end, this is where it fits on to the tractor's pto shaft, and there is a spring-loaded transverse pin which secures it, with a button visible at the bottom. Your pump should have similar splines, possibly with a similar transverse pin/button; or, there may be a collar around the shaft which you pull towards you to release it. If it hasn't been off the tractor for a long time, it may need a soaking with penetrating oil or diesel.

I wouldn't have thought you would need to remove the backhoe to get to the pump, although I am often wrong - just ask my wife

The pto shaft size is 1&3/8", 6-spline, a worldwide standard size.

If none of this is helpful, try to give us some photos somehow, then we can see what's what..

[Robhar]

Hey thanks Bob!!! That info really helped. I was not aware that there was a standard size and spline for the rear pto. I was able to get the pump off. The pump is a Cessna model 20644 imac. I don’t know what the letters stand for or how many gallons per minute. I was able to find a manual on line that I purchased for the backhoe but the part number is obsolete. Just my luck lol. Apparently Cessna made pumps for quite a bit of different things but went out of business awhile ago. My kids and wife aren’t here to help me with the picture thing but I will try to post some photos of pump and the picture in manual showing pump and gear box assembly. Like I said I am new to this but this thing is really forcing me learn things very quickly that I hoped I wouldn’t have had to learn for awhile. A farmer down the road whose been around for awhile and full of knowledge told me that sometimes they used the gear box to prevent you from over speeding the pump when you throttle up. Thanks again Bob

[Puffie40]

Cessna's hydraulic line was bought up by Eaton in 1988. You should be able to call up a hydraulic supplier and help you cross reference.

[blackbob]

I'm back from holiday, full of questions.. Is the pump repairable, have you had a look to see what has happened to it, have you looked inside it, did it suddenly stop pumping or has it gradually got weaker in output/pressure?
A pump is only 2 gears inside a casing, there isn't much to go wrong, it's either general wear or mechanical failure of its drive. Like your friend I am only a farmer, but I can't ever remember seeing a hydraulic pump stop working completely.

I know that a tractor's hydraulic output is measured in litres (or gallons) per minute, but I think that if you were to go shopping for a pump, they would likely ask you what cc (or maybe cubic inches?) per revolution you need, as they can be run at a wide range of speeds. I wouldn't think there would be any danger of overspeeding your pump on the tractor's pto, in fact for example a Farmhand loader has a gearbox to speed up its pto-driven pump? https://www.youtube.com/watch?v=e_BxtsqbgqI And I think you already have a pump on the front of your tractor which runs at engine speed, your pto shaft will never run at more than maybe half engine speed.

I make no endorsement of this company at all, it is just some random result I got from Googling 'hydraulc pump repair', but it sounds like it may be possible to recondition your pump, and maybe save the hassle of looking for a new one? https://www.apexhydraulics.co.uk/servic ... mp-repair/

[Robhar]

Hi Bob hope you had a great holiday. Thanks puffie for your help also. Yes I took the pump to a hydraulic shop and he tested it and it was weak. After he took it apart he showed me the body of the pump was worn and the tolerances were more than what he thought they should be compared to other pumps. He told me I might be able to run a heavier fluid and get some of my pressure back but he did not recommend it. He tried to find info. on pump but was not able to find much. He contacted Eaton who informed us we needed to contact an authorized dealer to help us first and if the dealer could not help us the dealer would then contact Eaton. After contacting several dealers we finally found one who sold Cessna pumps when they were in business. The dealer told me he could get me a pump for $1000.00 dollars but would not give up any info on what the numbers or letters meant. Since then I have found two different pump manufacturers that make pto pumps that mount right on the shaft eliminating the gear box. The one company wants $300 for there pump. I emailed them the pump model number of mine and what it was used for and asked them which pump they suggest I use. Hopefully I will get a response on Monday from them. The other company wants $450 for there pump and I have not contacted them yet. I to do not endorse any of these companies because I have not owned any of there products but if helps someone there names are Dynamic Hydraulics and Prince Hydraulics. So yes to your other question the power loss was over time. At first I would have to leave up on lever then pull back again to get the main boom to pick up with a load by the end I would continually have to leave up and pull back and it would move and inch.

[Puffie40]

The PTO pump might be your best bet as it's internally geared up to run with a 540 PTO. It eliminates the jackshaft your old pump might have and might make the backhoe more responsive.

Another option is to get rid of the rear pump entirely and run the backhoe with the engine-driven loader pump. You might have to replace the hydraulic tank with a bigger one so it can handle both circuits, but it will make it simpler to both operate and maintain.

If you still want to fight with the old pump, well, My dad is a mechanical engineer, and a lot rubbed off on me, so please bear with me.

Finding a replacement pump will require some engineering research if you don't want to fight with cross-referencing part numbers.

Gear pumps don't have much going for pressure, it's mainly flow rate for them. Most hydraulic valves have around 2000 - 2500psi relief. Engineers usually switch to closed-center piston pumps if they want a higher pressure system, so that means most gear pumps will have around the same pressure rating.

If you still have access to your old pump, we can do some measuring and figure out the flow rate. Here's a calculator for calculating the displacement of a gear pump: http://www.metaris.com/displacement-calculator.php

Most of those industrial pumps will have a standardized mounting flange, but will require some measuring to determine its type. If it has a standard keyed shaft, a generic gear pump should be fairly cheap.

[Robhar]

Thanks Puffie!!! Right now I have the hoe rigged up to run off of front pump. I installed a 3 way valve so I could select between loader and hoe. I am using the rear tank and it holds about 10 gallons. I ordered the rear pto pump but my estimated delivery date isn’t until August. Which isn’t to bad I was hoping earlier but now it does not matter because I just lost the clutch. After I get the clutched fixed, new pump on and get to play with it for awhile I will let everyone know how it works. Thank again for all the help I have a feeling I am going to need a lot of it. Lol

[Puffie40]

10 gallons is about right- the 580B backhoe we have has a 11 gallon reservoir on it.

The location of the tank at the back isn't ideal as it will be hard on the front pump (reservoirs are located as close to the intake as possible to reduce pump cavitation caused by excessive suction) but since you said the rear pump is being replaced it shouldn't matter.

[Robhar]

Yeah I thought the distance was a little far but the front loader tank is the actual frame of front loader. Maybe this is common practice like I said this is my first tractor like this. The problem I had using this is the valve block for the hoe directly dumps into rear tank through rear ports It’s like they use the tank as the back of valve block. I wasn’t real sure how I could get around this.

[blackbob]

Have you tried using the backhoe with the front pump, is it fast enough?

Because if you could pipe the return from the backhoe into the loader frame, you would have a similar layout to any modern backhoe-loader, and very like the early JCB's which were built on a Fordson Major chassis; with one, front-mounted pump (and also a little one for the power-steering). The oil flow is pump - front loader valve - rear (backhoe) valve - filter - return into chassis frame.

My thoughts were that, by making up a few big hoses, you could avoid the need for a second pump altogether? It would depend on your front pump being in reasonable condition; and also it would make removal of the backhoe more complicated if you wanted to use the tractor for other things.

Your machine sounds a bit like Oregon Dave's* - you colonial guys seem to have been able to make good loaders to fit the Fordson.. we had to make do with little things which could only lift approximately a spoonful: https://www.youtube.com/watch?v=EfPuMmAvNAw (when I was a kid we had a loader like that on a grey Fergie - pathetic little thing)

*See: http://www.fordsontractorpages.nl/phpbb ... f=2&t=7214 and before that http://www.fordsontractorpages.nl/phpbb ... f=2&t=7123 , Dave had some difficult fuel and electrical issues caused mainly by relying on people who didn't know much about Fordsons - but we on the Fordson Tractor Pages soon got him sorted