OSA 250 English lesons ;-)

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OSA 250 English lesons ;-)

#290433 Hallo everyone,

I bought Osa 250 (1988), it is my first forwarder and probably because of this fact I have some questions as follow. I found some technical instruction on "maskinisten.net" but unfortunately (for me) are in Swedish only.

So I would like to ask following:
In first row of IPS box one card is missing can some one tells me what controls? Extension of crane maybe?
Crane works (except extension) if black button in first card is pressed on.
Are this two things connected, or button on first card have some special task. If it's not on red light is on and right command stick doesn't work. What function has this black button at all?
Some pictures:

first card

I am also interested which type is 5th IPS card so I can order it by some one.

Too much question for first post? Sorry but I have plenty of them more. Thanks for help in advance.

A picture from machine before enter garage for "pit stop"


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Re: OSA 250 English lesons ;-)

#290472 Hello,and welcome :mrgreen:

No,a card is not missing :!:
Normally you need 3 cards+main card in an IPS -box but there is a space for a card no 4 if you need some extra hydraulic,like bulldozerblade.

On your other IPS box you have an extra card,but I think that is for steering of the machine.

The black button is a reset button.
If the red light goes on you have some probleme with elecktric.

Can be joystick,cables,IPS-box or magneticvalve.

What happens when you swich power on :?:

Is the red light on immediately or does it come on when you move the joystick :?:

If it starts in green and turn red when you for example move the extension on joystick,you have the probleme in cable between IPS box and magnetic valve or the magneticvalve is broken.

If it is red immideately the problem is inside the cab.
Try to swich joysticks,easy way is to swich connectors on IPS-boxes.
If the redlight probleme then goes to the other box you should check joystick

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Re: OSA 250 English lesons ;-)

#290601 Thanks you.

Red light switch on immediately when I start the engine. I will check like you write. And report of course.

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Re: OSA 250 English lesons ;-)

#290677 Sorry,but I forgot to ask what type of joystick do you have :?:
I mean if extension doesnt work.

In -88 Ösa used a type of joystick nicknamed "aphead",or "cathead".
They used the extension function at the (left) joystick to turn the machine.
Underneath the joystick there were 2 buttons,if you pressed one the extension was normal and when yoy pressed the other you could turn the machine with the extension buttons.

Meaning you cant turn and use extension at same time.

But many of those has been rebuilt using anothet joystick for steering monted side by the other

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Re: OSA 250 English lesons ;-)

#290738 I am in the middle of disassembling machine, so I can check command yet. The joysticks are different from original. There are two buttons integrated into the sticks. I must check electricity in total first.

Unfortunately I have different problem. Drive in trailer did not worked and we found that drive shaft on left boogie is broken. Could somebody recommend where to buy used one, or not to buy used one at all.


I am paying tax for greenhorns and stupidity. :twisted:


Re: OSA 250 English lesons ;-)

#290742 Hi Jeszt and welcome to skogsforum.se.
Try at Koppoms machine, +4657110184, or Stig's machine +4664244220.
They usually have the parts you are looking for.

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Re: OSA 250 English lesons ;-)

#314138 Uff, in last few month I spent my free time for some "hardware" operations.
I find out that rear drive shafts (both) has been broken because of damaged bearings, so I change them too.
star lezaj.jpg



tavelik lezaj.jpg


novi lezaji center.jpg

I the meantime, when I wait for spare parts, I change all kind of oils and oil filters, change high-pressure pump and diesel nozzles on engine and fix (change) many small things.

So I am at beginning again.

During the work on machine I partly lost the electric power in cabin, so drive, brakes (unbrake) and crane doesn't works. After I fix this, I am afraid, I will have lots of question again :oops:

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Re: OSA 250 English lesons ;-)

#314162 Good work! :-BD

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Re: OSA 250 English lesons ;-)

#318178 During test drive I noticed:
- machine start to move at aprox 10-15% of turn of potentiometer - could be a problem in potentiometer, oil pump or hydraulic motor (OK I must probably measure pressure in different parts first) - should machine start to move earlier ... at 5% turn ??
- by reverse drive machine start to move at 30% of turn of potentiometer - is this normal?
- by reverse drive machine drive slower at same position of potentiometer - is this normal ?
- by uphill drive forward works fine, by backward drive uphill in some point (very steep) machine stop moving in up to 50% of potentiometer cycle, if I open it to higher speed engine turns off
I still can not find why foot brake doesn't work, - parking brake works perfect in automatic position and full brake position
I lost also command for road drive (rabbit button -higher speed and turning of rear drive) it works before I start to work on machine

OK last stupid question for now
there is some kind of brake in the central section, I imagine that it's function is to slow linear movement between machine and trailer, but how do I control it ?
There (somewhere near this brake) is also some oil leak, can I just seal it or I will fall in to the troubles? I cant figure out if it leaks on pipe or in cylinder.


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Re: OSA 250 English lesons ;-)

#319492 No,you do`t have to turn the potentiometer at all,leave it at full (100%),but instead you should switch on the automatic button on,mounted on the front panel,markt "A"

You don`t need the footbrake!

The brake in the center of the machine you better forget too,it is too much trouble with that.But you have to plug the hoses,it gets oil from the lifting cylinder,and there is a returnhose as well.
These brakes was manufactured in different types,but no one was successfull,so you save a lot of problem and money if you learn to drive without it :mrgreen:

Fredrik Reuter
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