Shims and bolts keep shearing off of hydraulic pump drive. This happens when the front loader is picking up a load. We have replace these shims and bolts 2x Not sure what is happening. Is there a pressure relief valve that needs to be replaced.
hydraulic pump L48 broken shims and bolts
- Thread starter ms8599
- Start date
rbargeron
Well-known member
Lifetime Member
Equipment
L5450, L48, L3250, L345 never enough attachments
Is this the front pump? (See attached part layout) It sounds like a stiffness problem in the pump drive couplings. Are they assembled so they can flex? The pump torque isn't all that high but if the drive can't flex to absorb misalignment the bolts can break from high-cycle fatigue.
The listing shows the drive shaft coupling was "improved" after S/N 60261. Maybe related?
The listing shows the drive shaft coupling was "improved" after S/N 60261. Maybe related?
Last edited:
Been there, done that. Less then 10 hours after I bought it! When I called the dealer, the parts guy said he had never sold those fiberglass discs. I little chat with the salesman and they cover the costs of the parts ($45 for the shaft, $18 each for the disks x6!). It didn't help that I was over a ditch in between trees when it went, and of course I had the outriggers down, bucket down and ready to start digging with the hoe. That pump runs everything accept the side to side of the hoe so I had no choice but to fix it where it was.
A few weeks later it happened again. I new I wouldn't get anywhere with the dealer this time. I tried replacing the disks with conveyor belt material, thinking there would be more flex. Turned out it was too flexible and started to shred and pucker.
Next run, I made a new shaft from scratch. Then replaced the fiberglass disc and aluminum spacers with UHMW pieces. When I went to mount the new setup, I bolted it to the pump first and noticed it was way out of alignment. The pump needed to be shimmed to align it to the crank pulley.
Since re aligning the pump, I've had no issues. Knock on wood!
Sorry about the pictures out of rotation, first time.
A few weeks later it happened again. I new I wouldn't get anywhere with the dealer this time. I tried replacing the disks with conveyor belt material, thinking there would be more flex. Turned out it was too flexible and started to shred and pucker.
Next run, I made a new shaft from scratch. Then replaced the fiberglass disc and aluminum spacers with UHMW pieces. When I went to mount the new setup, I bolted it to the pump first and noticed it was way out of alignment. The pump needed to be shimmed to align it to the crank pulley.
Since re aligning the pump, I've had no issues. Knock on wood!
Sorry about the pictures out of rotation, first time.
Attachments
The front pump drive is a poor setup, in my opinion. There is no flex in the shaft, or very very little. This leads to a lot of things not limited to broken bolts and pump failures. Kubota did not properly address the fact that the front chassis of the tractor flexes a little causing misalignment.
If the bolts get loose, they'll break off as well, so that could be an issue worth eyballing.
The "fix" for the non flexible shaft is a semi-flexible shaft which is available from Kubota. Don't have the part number in front of me but they do in fact offer one that has more "give" to it than the more or less rigid shaft that comes on them. Even then, I like to use a dial indicator to set up the pump drive so that there isn't any side loading. It's not hard but it IS time consuming and to my knowledge kubota doesn't offer shims to "adjust" it either, so you have to make your own. I hate doing these!
If the bolts get loose, they'll break off as well, so that could be an issue worth eyballing.
The "fix" for the non flexible shaft is a semi-flexible shaft which is available from Kubota. Don't have the part number in front of me but they do in fact offer one that has more "give" to it than the more or less rigid shaft that comes on them. Even then, I like to use a dial indicator to set up the pump drive so that there isn't any side loading. It's not hard but it IS time consuming and to my knowledge kubota doesn't offer shims to "adjust" it either, so you have to make your own. I hate doing these!
rbargeron
Well-known member
Lifetime Member
Equipment
L5450, L48, L3250, L345 never enough attachments
I agree - the L48 is based on the Grand L10 chassis - which really is pretty maxed out masquerading as a 50 horsepower TLB. It has a rugged exoskeleton but some of the accessories (like the front pump drive, front axle) have their hands full.