Vermeer 1250 Turbo hydraulic issues

[Skidloadertech]

We have an old Vermeer 1250 Turbo chipper that a customer brought us. It keeps burning the belts off of the hydraulic pump. I got our in house machine shop to make a new drive pulley for the crankshaft as Vermeer don't sell it anymore. While we were at it we upped it to a B belt instead of a 4L or whatever it was. So now we have 2 new pulleys and it worked for a week but is back to burning belts off.
Now I am checking out the possibility of a relief valve set higher than it should be. I need to know what relief pressure should be and Vermeer won't help me or the customer. Vermeer always asks for a serial number and I can't find one, they tell me that it should have a sticker on it, ha ha its been repainted at least twice and is rusty now. I also can't find any info online for this old girl. So.... any info guys?

 

[Vetech63]

Pics of the set up would help. Pump, drive belts, etc....

 

[Skidloadertech]

Here you are. When we changed the pulleys we matched sizing for what was there. This problem really seems strange as our customer had this unit for at least 4 years and had only changed the small belt once or twice. This problem started in the last 6 months and he burned off many small belts before he brought it to us. We changed the pulleys because the engine one in particular was very worn on the sides of the V.

 

[Welder Dave]

With a single belt like that, there shouldn't be much load on the pump. Does the pump spin freely with the belt off? If not, maybe a bad bearing or damage in the pump. If the pump turns easily, something is loading the pump up. Maybe a valve is stuck or something is jammed you can't easily see. What does the pump control, power feed? Could be bad bearings or something similar there too. Can you see if what the pump operates will move freely on its own? Thinking if it is a power feed roller or similar, it should turn turn easily with the pump disconnected.

 

[Diesel Dave]

For what it’s worth, older Bandit chippers with similar style feed motors the feed wheel relief was set at 1500 psi.
I would think the NO LOAD operating pressure at full throttle with WARM oil would be max 200 psi.
There is a relatively new pump on there, any story what happened to the old one ?

 

[Skidloadertech]

There is nothing wrong with the pump. It is fairly new, the customer was having issues with the feed rolls not feeding about 6 months ago. We are primarily an agricultural dealer here and were swamped keeping tractors in the field at that time. I told him we couldn't look at it for 2 weeks and gave him a different local shop to try. There was no one local that had time for it so the customer removed the old pump and took it to a local hydraulic supplier, he told them that he wanted a new pump like it. They gave him a new pump and he installed it, there was no improvement. Which is no surprise because when I asked questions later, the old pump was also burning belts off. If the belt is slipping before system pressure is reached or at least feed role relief pressure reached it will never feed correctly. I did check out the feed roll motors a bit just as to not miss something, and I don't find anything wrong.
Thanks for the info about feed wheel relief pressure, this is the kind of info that I wanted out of Vermeer. They did finally tell the customer that the system pressure should be 2,500 psi , but I have no confidence that this is correct. The local Vermeer guys don't seem to know or CARE much about older machines. They either pull something out of their hats or refuse to try. If anyone has accurate specs about flow and relief pressures, I sure would appreciate it.

 

[mekanik]

An older Vermeer chipper I occasionally work on has the serial number
stamped into the top of frame just ahead of the axle on the right side.

 

[Vetech63]

3 questions
Is that motor running a chip rotor or a debris conveyor? I'm not familiar with that machine.

I can't see the type of belt you have on there. Have you tried a friction belt? Or a ribbed belt for running cooler?

Have you tried to decrease the relief pressure, say to 1500, and see if thevmachine will operate correctly at that? 2500 seems high for a belt driven pump.

 

[Tones]

I've just had a look at the photos, the pic with the gauge in it , at 11 o'clock from the gauge will be a flow control valve which controls the in feed speed. Where the handle is will be a normal control block which have 2 pressure relief valves, 1 for each direction. To diagnose the problem each component needs to be pressure checked starting at the pump (to get a base line reading) all the way to the infeed drive motors. the direction control needs to checked in both directions. One other tip, don't adjust anything until the checks have been completed.
Without doing these checks you are only guessing evidenced by the replacement of the pump.
The fix could be very simple like an 0 ring jamming a relief valve closed or a major like a cactus drive motor.

 

[Welder Dave]

I would bet with just 1 small belt the pump is only supposed to draw 10 HP max. and probably less than that. Either the motor(s) is shot or the feed roller is jamming possibly because a bearing piled up. I'd pull the motor off and see how the feed roller turns. If it turns free and smooth then have the hyd. motor checked out. Might be able to try the motor without having it hooked up. Something is binding up. Another thing you can do is cut the hyd. filter open and look for debris or metal filings.

 

[Tones]

I would bet with just 1 small belt the pump is only supposed to draw 10 HP max. and probably less than that. Either the motor(s) is shot or the feed roller is jamming possibly because a bearing piled up. I'd pull the motor off and see how the feed roller turns. If it turns free and smooth then have the hyd. motor checked out. Might be able to try the motor without having it hooked up. Something is binding up. Another thing you can do is cut the hyd. filter open and look for debris or metal filings.

But you are guessing Dave. Proper testing gets a proper diagnosis.

 

[Welder Dave]

I was thinking of basic simple checks the OP could do himself that don't require any special tools or gauges. Instead of going through belts (and a pump) make sure the feed roller turns freely. It's just a different way of figuring out where the problem is. I know any hydraulic pump run off a relatively small single belt wasn't designed to take much load.

 

[Skidloadertech]

I've just had a look at the photos, the pic with the gauge in it , at 11 o'clock from the gauge will be a flow control valve which controls the in feed speed. Where the handle is will be a normal control block which have 2 pressure relief valves, 1 for each direction. To diagnose the problem each component needs to be pressure checked starting at the pump (to get a base line reading) all the way to the infeed drive motors. the direction control needs to checked in both directions. One other tip, don't adjust anything until the checks have been completed.
Without doing these checks you are only guessing evidenced by the replacement of the pump.
The fix could be very simple like an 0 ring jamming a relief valve closed or a major like a cactus drive motor.

Just for the record I installed the gauge where it is to monitor main pressure relief. All of the rest of the system will fall under that. Directional reliefs and any other pressure you want to monitor. If the belt can not drive the pump to produce main relief pressure either the pressure is too high, the drive belt system isn’t adequate for that much HP (highly unlikely as it was built with a smaller belt), or wrong volume size pump for the speed it is running (could be likely since there was an undocumented customer pump change). To determine much with tests I need to know what flow and pressure requirements this unit was built with. I do have a flow meter and pressure gauges.
FYI we did back the main relief way down,1,000 psi and slowly increased it. We are still not slipping the belt at 2,000 psi.

 

[398370]

Well looks like covered all the bases only other thing I would check is crank shaft end play. If good probably speed control

 

[Welder Dave]

What does that pump power? Vermeer has good engineers. If that pump used more HP it would have been gear driven. Unless the new pump is considerably higher GPM and/or pressure something is causing the pump to work harder than it's designed. I just think it's worth checking what the pump powers to make sure it isn't binding and causing the problem.

 

[Tones]

Skidloadertech, have you checked that the flow control hasn't screwed itself in? No flow increases pressure. Again it comes back to testing instead of guessing.