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Author Topic: Valmet 840 brake problem.  (Read 2017 times)

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Offline Matixx49

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Valmet 840 brake problem.
« on: November 26, 2020, 02:57:18 PM »
Hello
I have A problem with my valmet 840 1996y 8Wheel
I dont know whats pressure set on break valve, and where is it. Break is very weak, and  red light indicator is on

Maybe someone knows where and what pressure I need to set?

Offline nativewolf

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Re: Valmet 840 brake problem.
« Reply #1 on: November 26, 2020, 07:03:12 PM »
@Gary C any ideas?
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Offline Gary_C

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Re: Valmet 840 brake problem.
« Reply #2 on: November 26, 2020, 07:59:38 PM »
The brake pressure settings are on the valves that are on the underside of the cab, accessible when you tilt the cab. But it is very complicated to diagnose and set the hydraulic pressure settings plus the brake settings. You have to start with the main pressure settings, then to the servo pressure and on to other pressure settings including brake pressures. There is also the parking brake system as well as the working brake system plus an accumulator pressure setting. Also it takes pressure in the brake systems to release the brakes as well as to apply the brakes.

So it's very hard to diagnose the problems without the manuals plus a set of test gauges. It is all spelled out in the manuals if you have those handy. If not, I could possibly scan mine but I have a 6 wheel 840 and doubt everything would apply to your 8 wheel plus there many different models within the 840 series. I believe mine is an 840F.

Where are you located? If you take your serial number to a dealer you can buy manuals for your machine.

I will warn you that I spent over two years and many thousand dollars chasing hydraulic pressure problems in the auxiliary valve system/brake system on my machine only to find it was a fifty dollar pressure regulator in the servo pressure system. If I had known what I was doing at the start, I could have avoided all that time, money and work by recognizing the servo pressure setting was not right.

Before I could help further I would need to know more. Exactly what red light is on? Is that the accumulator pressure is low? Does the hydraulic system cycle frequently to charge the accumulator? What brake is weak? Do you know that hydraulic pressure in the brakes actually releases the brakes except for the work brakes on the pedals?  I've never actually used the brake pedals on mine as the brakes automatically engage/disengage when you push the forward/reverse foot pedal. Do the brakes not release?

Also my machine is red and made in the US about 2000.
Never take life seriously. Nobody gets out alive anyway.

Offline Matixx49

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Re: Valmet 840 brake problem.
« Reply #3 on: November 27, 2020, 11:48:51 AM »
Very, Very, very thanks for answers!
When the motor is started, break relase.
The accelerator/break pedal work very good-the machine stop.
Foot break and working break is not working, t machine only slow, when the pedal is max applied.I have a book for machine, but only the construction, pressure is not write.
I have pressure gauge. There are pressure measuring points next to the engine qnd there are such pressure:
SERVOPRESSURE: 22.5---》32.5 BAR
FRONT BREAK: 0---》50 BAR
REAR BREAK: 0---》50 BAR
BREAK/ACCELERATOR: 55BAR
First pressure is when motor is start, the second pressure is when pedal break is press.
Thanks

Offline Matixx49

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Re: Valmet 840 brake problem.
« Reply #4 on: November 27, 2020, 12:00:48 PM »

Offline Gary_C

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Re: Valmet 840 brake problem.
« Reply #5 on: November 27, 2020, 01:08:48 PM »
I am not sure I understand your machine and suspect you have a different version of the 840. Is your machine a red or black one? They made both with the black ones an earlier version. On my machine there are no test ports next to the engine.

On mine the brakes are spring applied and it takes hydraulic pressure to release the brakes. So when I start my machine both parking and work brake are applied by the spring pressure. I must release the parking brake with a switch on the column between the right (facing the engine) windows which applies hydraulic pressure to the parking brakes. The work brakes are automatically released with hydraulic pressure when you push the forward/reverse pedal on the floor and reapplied when you take your foot off the pedal. I have never had a need to push the work brake pedal on the floor. That is why I do not understand how you say the brakes are weak. To me that would indicate the spring pressure is weak or the pads are worn, not the hydraulic pressure needs adjusting.

On my machine you can hear the engine load up for a short time to charge the accumulator and if the accumulator is leaking you can hear the engine cycle frequently when nothing else is working.

It helps to know where you are located. Please add that to your profile. 
Never take life seriously. Nobody gets out alive anyway.

Offline Matixx49

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Re: Valmet 840 brake problem.
« Reply #6 on: November 27, 2020, 02:32:25 PM »
I have a valmet 840 with black cab. Im from poland, im sorry, i add it to my profile in a moment.
After start the engine, i must turn off parking break with a button on cockpit, only then can i choose driving direction and i go.
As far as i know, when i press and relase the gas peadl, breaking the hydromotor.
I want repair working break - pedal break, he hardly responds to pressing.
When i press this pedal break, on cockpit turn on indicator light, when i turn the steering wheel, indicator light goes out, but machine does not stop.

Sorry for the confusion, but im new, thank you so much, for you interest in my problem :)

Offline Matixx49

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Re: Valmet 840 brake problem.
« Reply #7 on: November 27, 2020, 02:36:21 PM »
 <br
>
 

Offline Gary_C

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Re: Valmet 840 brake problem.
« Reply #8 on: November 27, 2020, 04:22:33 PM »
Don't be sorry, your English is far better than my Polish would be.
I am not sure what that indicator light means. Is it described in the operators manual? 

I may not be of much more help as I am not familiar with those black painted 840's. Valmet made so many different versions and assembled them both in the US and Europe. So there are US made versions which mine is and Sweden/Finland made versions which apparently yours is. What you are describing may be more like the 540/640 versions made in the US and I am not familiar with those brake systems.

What I believe is all of those brake systems are fail safe so they are spring applied and hydraulically released. Also those brake pistons in both the front and rear axles are prone to leaking So if the brakes are not working it may mean either the springs have failed or the hydraulic release pressure is too low. If the hydraulic pressure has been low for some time, the brake pads may be badly worn. Also there are set bolts on each axle which are normally used to release the brake spring pressure. It may be they need adjusting.

The problem is to set any of the pressures you have to start in sequence with the pump pressure and engine RPM's, the standby pressures, the reduced servo pressures and on to the brake pressures. Without the machine manual it's going to be difficult to get the setting right and perhaps see where is the problem. Do you have a dealer nearby where you could take your serial number and order a manual for the machine?   
Never take life seriously. Nobody gets out alive anyway.

Offline Matixx49

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Re: Valmet 840 brake problem.
« Reply #9 on: November 27, 2020, 05:05:01 PM »
I can see, that you have a lot of knowledge about these machines, i enve you that! :)
In fact, front break pistons,unless, leaking little.
You dont know, what pressure should be ok ?
You dont know, if i have to remove boogie to replace the disc, and the piston?
Where can i find these spring relase bolts?
I will write an email to the service, asking for manual, do you think that pressure will be shown there? There is no pressure in my book with number parts.
Thank you very much for your help, sorry far so maaany questions :)

Offline Gary_C

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Re: Valmet 840 brake problem.
« Reply #10 on: November 27, 2020, 05:32:06 PM »
There are three manuals, an operators, service, and parts manual. Yes the instructions for setting all pressures are in the service manual and some are in the operators manual.

On my 840 I did once have the bogie out of the machine but I'm not sure if it is necessary to completely remove the bogie. I may also have to find out as I now have an oil leak in the left side of the bogie. I know the right side brakes have been resealed once before. The brake release bolts have a locking nut on them and they are near the center housing. I also think they have square heads.

Never take life seriously. Nobody gets out alive anyway.

Offline Matixx49

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Re: Valmet 840 brake problem.
« Reply #11 on: November 28, 2020, 02:29:16 PM »
Hello
Very, very thanks for help.
I will write message to service about service book, i will check bolts, and pressure.
If i have a problem, i will post on the forum. You are a great man, In Poland for 3 years i couldnt find any help, thanks again!   ;D

Offline Matixx49

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Re: Valmet 840 brake problem.
« Reply #12 on: January 14, 2021, 03:23:20 PM »
Hello 
@Gary_C Can you help again?  ;D
Some time has passed, I decided to disassemble it, I tried to buy a service book in the Komatsu, but it is no longer available.
Can you tell me what do you think about this disc plate? The spring were blown and the o-ring was blown. Do you think i have to undress it further?
I still don't know what pressure should be set so as not to blow it up again, service can't help me, or doesn't want to, i don't know anymore :D

I attach photo, and thanks.

  

  

  

  

 


Offline nativewolf

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Re: Valmet 840 brake problem.
« Reply #13 on: January 14, 2021, 06:38:18 PM »
Try the guys at Roland Machinery.  They deal with and service a ton of Valmet forestry stuff.  They've had turnover so I can't say for sure who to speak with but they have manuals parts etc.  Or at least they did 2 years ago.  Also very easy to get through, no Komatsu headaches.

Roland Machinery - Product Support

Gary would know best though.
Liking Walnut

Offline Gary_C

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Re: Valmet 840 brake problem.
« Reply #14 on: January 15, 2021, 05:27:56 AM »
I looked at your pictures and the parts do not look anything like the bogie axle drive I have on my 840F. I did call my best dealer in Escanaba, Michigan, Roland Machinery (906) 786-6920 as nativewolf also suggested. They are now a Komatsu dealer but were the Valmet dealer that originally sold my machine and they are located right close to the old factory in Gladstone, Michigan where the US made Valmet machines were assembled.

They are also unable to order any manuals other than the ones made in the US. The US made machines have a serial number that starts with an F. However they do have all the manuals including the EU made machines in their shop but not for sale so they can be a big help if you can contact the Escanaba location with your serial number. If you have difficulty with contacting them directly you can send me your serial number and I can try to be a go between if necessary. It would also be good to have an overall picture of the machine and the bogie axle where these parts came from.

There is a very detailed procedure listed in the service manual where you have to do in sequence to set and adjust all the pressures in the machine starting with the hydraulic pumps and then servo pressures, brake pressures and then on to crane functions. That is why I cannot tell you what the brake pressure are supposed to be set at because the brake pressures depend on a correct pump and servo pressure setting. Plus the pressures are different for each type of axle and each brake system. I think there are three types of brakes on that machine including parking, working and service (foot petal) brakes.

I hope this is some help and let me know if I can help further.
Never take life seriously. Nobody gets out alive anyway.

Offline Matixx49

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Re: Valmet 840 brake problem.
« Reply #15 on: January 15, 2021, 09:34:30 AM »
Thanks for the answer, you help me a lot.
 Unfortunately, as far as I know, the plate with the serial number on my machine is damaged and I cannot see what was on it. But I took some photos with the numbers on the parts, maybe this will help something.
 I called the service in Poland again, and the O-rings will be available, so I can put it together. Only the problem with the correct setting of the pressures remains. I am also trying to buy a service book from sources other than Komatsu Serwis, it may work, but unless I have it, any information from the site you called will be very important.
Thanks to what you wrote, I already know why my crane lifted less than it should - probably it has to do with blinded brakes.

These are the photos of the boogie from which I took the part that was in the previous post:



 

 

This is a picture of my machine:


 

This is a photo of what I disassembled:



 
Photo plate in the cabin:


 

Photo of the numbers on the outside of the wheel:



 

The photo of the numbers on the inside of the wheel, that is, disassembled, I showed in the previous post:





 




I hope that now you know more or less what it shows, if you are able to contact the service again, please do so, maybe by the numbers of these parts you will find something out, and maybe you can find some information in the service books about the settings these pressures. 

Offline Gary_C

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Re: Valmet 840 brake problem.
« Reply #16 on: January 15, 2021, 04:30:40 PM »
You should be able to find the serial number stamped right into the main body of the machine. That bogie is different from my 840. It looks like the bogie axle used on the 546 Valmet machines.  
Never take life seriously. Nobody gets out alive anyway.

Offline snowstorm

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Re: Valmet 840 brake problem.
« Reply #17 on: January 15, 2021, 07:54:29 PM »
546 646 used naf 

Offline snowstorm

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Re: Valmet 840 brake problem.
« Reply #18 on: January 15, 2021, 07:55:35 PM »
and they were chain drive

Offline Matixx49

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Re: Valmet 840 brake problem.
« Reply #19 on: January 16, 2021, 07:30:00 AM »
Hello
 I found the nameplate on the bridge, will it help? Maybe the service after the serial number of the bridge will know the serial number of the entire machine?


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