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Volvo 861

Clarence Boddiker

Clarence Boddiker

Member
Joined
Dec 28, 2022
Messages
9
Location
Ireland
Hey all,
I just joined up here in the hope that someone could help me out.i have an old Volvo 861 articulated dumper that the 6x6 has not worked on since I got it earlier this year. the selector lever moves from hi to lo ratio but when moved to engage all wheel drive nothing happens.
All useful advice welcome.
Thanks in advance
 
sfrs4

sfrs4

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Jul 22, 2013
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parts admin
Before anyone tags me in this..... I have no knowledge on the 860/861's they are well before my time and even that of our 20+ year served fitters, so as the dragons ( sharks in America ) say " I'm out "
 
Nige

Nige

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V

Volvomad

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Jul 13, 2011
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Did u try the ecu. I only ever saw 4 x 6 versions and all my little knowledge starts at the skip
 
sfrs4

sfrs4

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Jul 22, 2013
Messages
697
Location
Great Britian
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parts admin
@Clarence Boddiker, so one of my very good customers is a follower but not joined on here, and saw this thread, he emailed me last night with some information which could be useful, so thank you Marcus. and below is a copy of what he sent

I still do possess some knowledge on these machines, having worked with them back in the 1980’s as the 6x4 version was the tool of choice back in the day and very reliable.
The selector valve built into the column shift lever was pneumatic and differed from the 860S predecessor that used a three position electric switch to control air flow to the differing H/L solenoid valves, but both types still actuated a small air cylinder that engaged the PTO and sent drive out to the centre axle via the torque multiplier box.
It looks like the truck in question may be a 6WD variant, these were introduced in 1985 but weren’t a great success due to the use of the same TD60B engine employed in the 6x4 types which left the machine somewhat underpowered.
Breakage of the same small propshaft inside the rear belly plate that fed the multiplier box was common, due to the extra wind up the second driven axle placed upon it and wonder if this is what Clarence’s truck is suffering from ?
I hope something here helps you.
 
Clarence Boddiker

Clarence Boddiker

Member
Joined
Dec 28, 2022
Messages
9
Location
Ireland
sfrs4 said:
@Clarence Boddiker, so one of my very good customers is a follower but not joined on here, and saw this thread, he emailed me last night with some information which could be useful, so thank you Marcus. and below is a copy of what he sent

I still do possess some knowledge on these machines, having worked with them back in the 1980’s as the 6x4 version was the tool of choice back in the day and very reliable.
The selector valve built into the column shift lever was pneumatic and differed from the 860S predecessor that used a three position electric switch to control air flow to the differing H/L solenoid valves, but both types still actuated a small air cylinder that engaged the PTO and sent drive out to the centre axle via the torque multiplier box.
It looks like the truck in question may be a 6WD variant, these were introduced in 1985 but weren’t a great success due to the use of the same TD60B engine employed in the 6x4 types which left the machine somewhat underpowered.
Breakage of the same small propshaft inside the rear belly plate that fed the multiplier box was common, due to the extra wind up the second driven axle placed upon it and wonder if this is what Clarence’s truck is suffering from ?
I hope something here helps you.
Click to expand...
Thank you and Marcus for this very helpful response
 
sfrs4

sfrs4

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697
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So Marcus is still watching lol, it's like having a guardian angel on my shoulder, I had an email on Saturday which i have copied below

These dumpers have no ECU and employ a simple 12 volt system with very straightforward electrics.

4 or 6 wheel drive is actuated purely by air, the only electrical bit on that side of things was a warning lamp on dash which indicated when H-L ratio was in the neutral position.

This lamp would glow continuously however only when the thin plate that contacts the microswitches would break. The quick fix was simply taking out the bulb to stop drivers parking up !

Provided the air system was charged to 8 Bar, you could always hear air passing through valve when lever was moved to the H L 4 (or 6) positions.

First thing to check would be to see if the ram moves when valve is cycled, this just involves dropping the rear belly plate and have someone watch it.

Have all air tanks been fully drained of sludge, as this could also block the small air lines in the system ?

There were no air driers on the 861’s
 
Clarence Boddiker

Clarence Boddiker

Member
Joined
Dec 28, 2022
Messages
9
Location
Ireland
sfrs4 said:
So Marcus is still watching lol, it's like having a guardian angel on my shoulder, I had an email on Saturday which i have copied below

These dumpers have no ECU and employ a simple 12 volt system with very straightforward electrics.

4 or 6 wheel drive is actuated purely by air, the only electrical bit on that side of things was a warning lamp on dash which indicated when H-L ratio was in the neutral position.

This lamp would glow continuously however only when the thin plate that contacts the microswitches would break. The quick fix was simply taking out the bulb to stop drivers parking up !

Provided the air system was charged to 8 Bar, you could always hear air passing through valve when lever was moved to the H L 4 (or 6) positions.

First thing to check would be to see if the ram moves when valve is cycled, this just involves dropping the rear belly plate and have someone watch it.

Have all air tanks been fully drained of sludge, as this could also block the small air lines in the system ?

There were no air driers on the 861’s
Click to expand...
Marcus is a great help,thank you.yed I have checked that the ram is moving and it is,so that is a plus.i wonder if adjustment on said ram would help in any way ?
Again thank to all for the help.
 
Nige

Nige

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Jun 22, 2011
Messages
29,400
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G..G..G..Granville.........!! Fetch your cloth.
Clarence, looking back at your OP you mentioned that you acquired this truck fairly recently so you likely don't have any knowledge of its previous life. Have you considered the possibility that some previous owner was into the drop box or transmission and removed something in order that the machine could never be used in 6x6 mode.?

I'm basing this comment on Marcus's earlier thoughts - "It looks like the truck in question may be a 6WD variant, these were introduced in 1985 but weren’t a great success due to the use of the same TD60B engine employed in the 6x4 types which left the machine somewhat underpowered."
 
Clarence Boddiker

Clarence Boddiker

Member
Joined
Dec 28, 2022
Messages
9
Location
Ireland
Hi Nige,that's an interesting point,that may well be the case.i guess I can only hope that the last owner was telling the truth when he said it had worked when he had it. If I knew what to open and inspect it maybe I could find the answer and go from there. It's mostly dry ground work I want it for but 6x6 would be handy at times if I was getting stuck.
 
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