Mechanical Q for the smart guys???
 

This is a hydraulic oil pump from one of our skip loaders. It is the third to fail on two different tractors. Of course, you have to replace the entire pump - no sub parts available.

It mounts to the front of the crank. The spline only engages about half its length.

Pump is $1100!

Anyone have an idea on how to repair the spline? A welding technique? We are experimenting with drilling and inserting a pin/key - we've got nothing to lose on the old parts.

Any better ideas? Any help would be most appreciated.

Have pics of the splined shafts, and the failure?

Sorry - they didn't attach

http://forums.pelicanparts.com/uploa...1359411773.jpg

http://forums.pelicanparts.com/uploa...1359412025.jpg

http://forums.pelicanparts.com/uploa...1359412101.jpg

The pump is always engaged, and since it's pushing oil, I would not expect those splines to get a lot of hard impacts, but I don't know.

Are sure that is the correct pump? The splines should and need to fully engage.

nevermind... I was slow to post and photos are now up.

It appears the driving splines are worn out.

Or, have the female splines in the crank worn to a point that they are taking out the pumps male splines? Have any pictures of the crankshaft?

Paging Lubey....

:D

Seriously, though, I'm with URY914--if the splines aren't engaging fully then something is wrong.

yeah this for sure. If the splines in the crank are flogged out, it'll chew up any new shaft you put in there.

As to repairing the pump, you may be able to get a decent machine shop to make a new shaft for you. Hate to tell you though it'll probably cost as much as the replacement pump.

a good motor repair shop can cut off a shaft of a new motor and weld a splined shaft on..
Motor should have relatively cheap

We replace both male and female ends each time. Setup is from-the-factory oem.

Is that fretting due to a mis-alignment?

Install the parts together outside of the tractor. Is there wobble between the female and male parts? If there is are the parts in or out of spec/measurement?

Is the driver of the female part out of round? Can you manipulate the female side by hand when it is installed?

Mark the female side that points out to verify round. Manipulate the female part as it is installed. Verify that your female part moves in round.

Man, the places I could go with this post....nah, too easy. :D

Thanks for the input. For the record, these parts are failing in an as-installed-by-the-factory manner. There is A LOT of movement between the engine, the chassis and everything else due to the forces on this motor. All I can guess is that there has to be a little bit of play on that shaft due to expected movement. We keep replacing both the male and female but the time between failures is substantially less than all the other parts on the tractor. To me it is a design flaw, but what I need is way to fix what I've got.

make and model of the pump?

Thanks for your help Sammy. IDK but I will try to find out. It's oem on New Holland.

Are you saying the pump is hard mounted to the tractor while the engine is free to 'float' on its mounts?

It's trashed. I would be concerned the mating part is not taking fully advantage of the spline.

I'm surprised there isn't a replacement part for the shaft. I would explore that first.

Thank you. I have explore the options of. New shaft, but they only sell the whole pump. Since this is the oem configurations and since it has failed ontiple tractors, my question is, can u think of a way to fix the spline? Welding? Drilling a hole through it and bolting it?

How about drilling the coupler and the shaft and using a shear bolt.

Based on the pictures,
there is too much shaft misalignment,
does the pump have any alignment collars that hold it centered?
For the splines to wear like that something is moving off center or the shafts are not concentric,
not to mention the connection looks like it has not had enough lubricant

Really need pictures of the other part that this pump connects too.
I wonder if the pump shaft could be turned down some then a nut fitted and welded to the shaft then weld a thick wall 6 sided socket to the other side,
then add a good helping of moly grease to the connection

Have you brought up the issue with New Holland. Something is wrong if you are going thru that many motors.

What does the mating part look like?
How long is the internal spine on the mating part?

One more question: Can you take apart the pump and remove the shaft.

(other than engagement..)
Could the crank bearings be worn or flexing under load?
Could there be fluid blockage or undersized hoses, creating too much load?

What the psi?
Who's the manufacturer?
Do you know for sure that you are not getting air in the system?

I think Scott asked the right question. If the pump is mounted to the chassis then the engine must be rigidly mounted too. If the engine can move the pump must be bolted to it and not to the chassis.

regards,
Phil

The pump is registered for alignment. As long as the fit and surfaces are good, alignment should be good.
The amount of engagement is adequate: 1 times diameter is OK, 1 1/2 times is optimal.

If it was put together dry, duh.
if it was put together with good ole EP grease, that's bad 2. The oil will quickly separate from the binder and cause that kind of wear.
We use spline lube from sundyne on the only spline drives we still run, works well.

http://www.corrosion-products.com/CPE/GE%20Web%20Site/API%20Sundyne/lmv_313_iom.pdf

Iffn it gets packed with mud all bets are off, we'd have to seal it with o-rings. Yes, it can be done.
The spline is heat treated and slightly annealed, weldings not an option.

If we can ID the pump, I know a guy at Kaman industrial supply that can probably track it down and get parts from the real OEM and save $$$$ He's been doing it for a really long time and is one of the best.
I spent a whole bunch of years as a pump reliability engineer. Now I just run the daycare center.

BTW I'm better the female spline drive is shot too based on the wear.

As questioned, if the pump is solid and the engine floats, even a small amount you will never fix the issue. The vibration of the engine will wear the splines out no matter what. Some possible fixes:

- float the pump
- what is behind that flat surface around where the shaft comes out of the pump? Can it be machined off to give additional spline engagement?
- What lube and how often is it lubed? I would grease it every couple hours with moly.
- Solid engine mounts to make alignment more accurate.

I know abolutely nothing about it. But looking just from the picture, it looks like the wear at the center & left side of the spline is more than the right. It also looks like the grooves are worn in a dish shaped contour. If that's the case, it might be an alignment problem. That doesn't look likely, since it looks like the pump collar seats into a recess and gets bolted down. I doubt New Holland would make a design mistake like making the engine mounts able to move while the pump base doesn't follow along. Have you tried something like putting some colored material on a new set of splines & inserting it & withdrawing it to look for a pattern? Just a rookie comment.

What about manufacturing a new shaft of better material and taking in cores from other people and rebuilding them with YOUR improved shafts for a profit.

I believe its an alignment problem or the fact that the motor and engine are not as one unit.
I don't know if this will help or not but what is your standby pressure? Thats the presurre that flows through the pump at all times, most of these are constant displacement pumps - if its spinning its pumping. If your system puts out 1000 psi and your standby is 200 psi there is a big shock when you use that curcuit, try a higher standby pressure to soften the shock of starting when you use that curcuit. There should also be a relief valve in the system that will bleed a bit of pressure from your system as your cylinder reaches it max extension, you might want to up that pressure relief. I'm not an expert, just around it all the time and learned a bit from the experts, unfortunatly I only learned enough to make me dangerous.
Finn

My guess - the bearings are worn in the shaft with the female splines, causing misalignment.

+1 with wdfifteen.

I agree with what has been said above. However, IF the pump and the engine are ridgid, the wear is unexpected for me. I think the above nails it.

IF this is not the case or you can't fix the crank wobble. Here is a thought.

Something that you could try however is to buy a male spline in SOFTER material than the female and attach to the pump. You would have to cut the pump's shaft back to allow for this. The softer spline would be sacrificial. You would need to replace / maintain it more often but it would be the planned point of failure.

Great question.

Larry

Thanks for all the great info.



The motor is hard mounted to a bracket off the chassis, on this model and the older ones too. This piece (currently being drilled) is what attaches to the crank - I did a bit more research and learned that every model previous to this one has a grease fitting. Why they left it off this one is anyone's guess.:

http://forums.pelicanparts.com/uploa...1359484602.jpg

http://forums.pelicanparts.com/uploa...1359484643.jpg

Pump info:

http://forums.pelicanparts.com/uploa...1359484747.jpg

At this point we have not gone inside the pump as we can't get a new shaft.

With respect to alignment, there is no adjustment. However, I know the motor moves about when under load.

LOL that looks like the front driveshaft from an AWD BMW
They do precisely the same thing-- except while you are driving

David
Can you get a shot of the actual front of the crank too?
It doesn't look like there's much in the way of alignment going on from what you've posted.
I was expecting to see a female portion where the flange would index the pump to the part that the splines would be coming out of. Kind of like a hub centric wheel indexing.

New motor mounts?
Put it under load and measure how much it shifts.
That doesn't seem right. Fixed pump with floating engine? Seem they should have stuck a u-joint in there.

s_morrison57 mentions hydraulic shock/kickback.
Is there some kind of a anti-hammer valve product to reduce this?

I was playing with a friend's newer Kubota backhoe, which was kicking and jerking.
Turned out one of the return recirculation hoses was kinked and made the hydraulics funky.
Smoothed out after an external collar straitened it.