743 breakdown

[boumatic]

Hello everyone, we own a Bobcat 743. It has done a good job the last 3 years. Today I started the loader, driving backwards a few seconds. Suddenly there was a mechanical rappel, the machine was shaking und suddenly the hydraulic function went down. No more driving, no more lifting the arm. Motor runs. Did someone experienced that behaviour ever before? What could be the issue? Thank you all for your help and experience!

 

[flyerdan]

It sounds like the U-joint between the engine and Vickers pump has failed, that would account for the loud noise as the grenaded parts hit the fan and got flung about. Of course, this completely discouples the engine from the hydraulic drive, so that fits you symptoms. Hopefully, the damage will be contained to the joint and not the yokes or input shaft of the hydraulic pumps.

 

[Tazza]

It sounds like the U-joint between the engine and Vickers pump has failed, that would account for the loud noise as the grenaded parts hit the fan and got flung about. Of course, this completely discouples the engine from the hydraulic drive, so that fits you symptoms. Hopefully, the damage will be contained to the joint and not the yokes or input shaft of the hydraulic pumps.

My guess is the universal joint too. Hopefully there is no other damage, when these joints go, they can break or bend the input shaft to the pump.
If you lift the cab, lay on the pump and put your hand in the blower housing, there will be a joint that connects to the fly wheel, feel for it it is floping around. If so, that's your problem. Time to pull the motor out, not a hard job.

 

[wbecker]

My guess is the universal joint too. Hopefully there is no other damage, when these joints go, they can break or bend the input shaft to the pump.
If you lift the cab, lay on the pump and put your hand in the blower housing, there will be a joint that connects to the fly wheel, feel for it it is floping around. If so, that's your problem. Time to pull the motor out, not a hard job.

This is what mine looked like when I pulled the engine to replace a rusted out hydraulic line.
I think I got it just in time.

 

[Tazza]

This is what mine looked like when I pulled the engine to replace a rusted out hydraulic line.
I think I got it just in time.

Wow..... That sure was close to falling apart!!!

 

[wbecker]

Wow..... That sure was close to falling apart!!!

So Tazza, what did I do wrong trying to post that U joint picture, and what did you do to fix it?
I got "lucky" the hydraulic tube that runs across the bottom forward of the engine rusted out so I had to pull the engine to replace the tube.
Bill B

 

[Tazza]

So Tazza, what did I do wrong trying to post that U joint picture, and what did you do to fix it?
I got "lucky" the hydraulic tube that runs across the bottom forward of the engine rusted out so I had to pull the engine to replace the tube.
Bill B

All i do is load the image that you had hosted on photobucket, right click/copy then back into the message, right click/paste and it shows up.
Those tube lines are in a silly place, the bottom two are the ones taht always seem to get pin holes, thankfully when i had to work on some, i just wire brushed them and used bronze and an oxy torch to patch them up.