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Haas 2007 VF4 on its second gearbox in 3yrs, any suggestions

zachrabbit15

Plastic
Joined
Feb 27, 2020
Hello all
We have a Haas VF4 15K spindle with the 30hp direct drive. Haas replaced the gear box 3 yrs ago (turns out it was a bad shifting solenoid and they ate the cost). It went out again on Thursday but this time it is the gearbox. That machine cuts a mix of alum and 4140 steel. I don't do a lot of heavy hogging on it, mostly use Hi-feed cutters to do most of the material removal when running steel. Anyone else ever have a machine go through a gearbox that fast? Is there anything else I should start looking at that may be helping it to the early demise? Last does is there a service that sells rebuilt gear box for a better price than the $8K plus labor Selways want for another replacement?
 
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MaxPrairie

Hot Rolled
Joined
Jul 9, 2015
Is the problem the gearbox won’t shift or shifts sometimes and other times stuck? We have rebuilt the gearbox in one of our machines before. It isn’t impossible to do. Are you shifting gears often? I dropped my gearshift rpm lower to eliminate as many gear shifts. Basically only when it taps it is used in low.
 

zachrabbit15

Plastic
Joined
Feb 27, 2020
Thanks for the reply, last time it wouldn't shift and the tech said to replace the gear box. That did not go so well for Selway, that had to eat the labor cost and half the price of the gear box.

This time its making a god awful noise and I get a alarm for spindle speed not matching the programmed RPM. When you hit stop the spindle continues to spin. Have to hit e-stop to actually turn the spindle off. We had another service company come out and check the machine and they said gearbox, we are having a Selway tech come out and give a second opinion, cover our ass just in case.
 

MaxPrairie

Hot Rolled
Joined
Jul 9, 2015
Sometimes the gears with develop burrs on the teeth from shifting back and forth over time. These burrs will eventually cause the gearbox to have trouble shifting. This was one of the things wrong with mine. The other thing on mine was the shifter shaft had worn and (if I remember correctly) wasn't sealing allowing air to pass by the oring. We took the gears out, polished the burrs off and machined a new piece of 5/8 TGP for the shifting shaft. It was a labor intensive but relatively cheap fix to do in our shop. We built a gantry that spanned over top of the machine and used a come along to remove it. Forklift probably also would have work. The Haas machines are pretty simple designs and once you get looking at stuff you can usually figure out the issue.

I am not sure what would cause a problem shifting and then allow the spindle to spin, but stop when the estop is hit. Either the gears are engaged or they aren't. If you are getting a Gear Fault alarm, that would lead to the above issue or lack of solenoid pressure.

Edit: The "god awful noise" could have been the gear partly engaged, MAYBE, and the teeth grinding. You would think the prox sensor would catch that the gear are not fully engaged however.
 

SageGlad

Plastic
Joined
Apr 16, 2022
Hello all
We have a Haas VF4 15K spindle with the 30hp direct drive. Haas replaced the gear box 3 yrs ago (turns out it was a bad shifting solenoid and they ate the cost). It went out again on Thursday but this time it is the gearbox. That machine cuts a mix of alum and 4140 steel. I don't do a lot of heavy hogging on it, mostly use Hi-feed cutters to do most of the material removal when running steel. Anyone else ever have a machine go through a gearbox that fast? Is there anything else I should start looking at that may be helping it to the early demise? Last does is there a service that sells rebuilt gear box for a better price than the $8K plus labor Selways want for another replacement?

Hey. This gearboxes are very simple. Just 4 parts basically. I would look at the gears changer, not just a solenoid (because you would have a different problems) but the actual shifter. There as a hidden problem may exist, the snap rings inside this cylinder are very small and thin. On my vf7 the bottom one just cracked and fell apart. And I didn’t notice this till I removed the gearbox for rebuilt. If you have a similar problem (broken snap ring) you very unlikely can recognize that it actually acting weird, but it won’t shift the gears on time and the spindle motor doesn’t see it, it just going accordingly to the command.
Hope you will figure it out, it’s not a big deal to rebuild this shifter or replace it. I’m ended up just replacing snap rings, o rings and polished the shifter shaft and cylinder.
Good luck!
 








 
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