Volvo gearbox

D

DownWest

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First: Bit of history.
Boat is wooden double ender built in Sweden in the 50's. Engine is a Vovo B18 petrol 4 cyl, fitted in 1970, driving a UTV1 direct box. Present owner used it on the local river for 10yrs.
The problem is that it will not stay in neutral. If left running it will drift into either F or R.
The shift lever has hefty indents for F-N-R, but the actual engagements occure between the forward and neutral indents. The lever will not go as far as the rev. indent.
Looking at the Volvo parts diag. It would seem that the output shaft moves fore and aft so that the prop force keeps the cones engaged. I have read here somewhere that this is not unusual in Volvo boxes. It appears that the shaft is limited in it's travel by the cones being too close together? Owner says nothing has been done since he bought it and the travel at the lever is normal (he is non-tech)
Before we strip it down, does anybody here have any idea what is going on?
Comments gratefully received.
I did unbolt the shaft flange and there was a bit of mis-alignment, but it has always been thus.
Thanks
Andrew
 
Had the reverse problem due to cone wear and excessively lubey oil which caused the cones to slip. The box has got the correct oil in it, hasnt it? I always thought is was the shape and surface of the cones that caused them to grip, and the movement of the shaft was a consequence - certainly polished cones often need replacing.

Other than that, its likely to be wear in the actuating lever I would guess.
 
Thanks, oil is at level and (re: advice on here) same as engine oil. What do you use?
The limited travel means that the neutral has no indent to keep it so. But, there is no apparent movement in the lever as it drifts into gear. I took out the selecter, and all looked as new with no slack in the pin that moves the engagement sleeve. The shaft shows movement as one shifts, but nothing like enough to use the full range of indents.
I also thought the cone taper was the engagement, but the shaft def. allows the prop to help. Don't think polishing is a prob, as OK when engaged.
A
 
Before we strip it down, does anybody here have any idea what is going on?
Comments gratefully received

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Usually the motion of the reverse lever to the forward/reverse detended lever on the box is converted to the sliding motion of the cones by an internal arm whih has a block runing in a grove of the cone assembly. MAybe even two blocks diametrically oposed. It sounds like these blocks and or the grooves they run in are worn. This will allow the cones to wander around and take up engagment in forward or reverse.

A good machine shop should be able to make new parts for you to fit the worn grooves.

Is your engagement sleev as you call it a good fit on the cones? If the selection system is all free of end float is it possible that there is internal wear on thrust bearings allowing end float within the gear box.

The fauly you describe indicates that under normal operation there is relative axial motion taking place while in neutral between the cones and clutches. If as you suggest the cones are not floating fore and aft then it would seem the clutches are ????? This could only happen with baddly worn bearings.

The only other thing I can think of is oil drag on the clutches however you appear to have covered this by checking the oil.
 
Thanks for reply BD, but in this case the groove is in a tube around the tail shaft. The clutches are further forward in the main housing.No slack in the block/groove and no wear on the block (original machine marks vis. ) Any wear must be further up in the clutch area, but is not consistant with the limited movement.
I was hoping some-one here might have had a similar prob.
A

Ed: The cones are the clutches, and according to the diag, are in an assembly attached to the front of the tail shaft. The poerating sleeve is concentric on the tailshaft and moves the whole assembly for and aft. It is this movement which is limited, apparently by the cones being close to each other so the space between F &R is very small.
I feel a dirty hands moment coming on
A
 
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I feel a dirty hands moment coming on
A

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I think you're right. My experience was with a cone clutch Yanmar box. The answer to the question about oil was that we replaced the gearbox oil (must be non Hypoid) with SAE 10 to get grip. If you have very thin engine oil in a bax that needs gear oil it might well make a difference but my money is on wear.
 
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The shift lever has hefty indents for F-N-R, but the actual engagements occure between the forward and neutral indents. The lever will not go as far as the rev. indent.

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Looks to me that there has been movement between the operating lever and the lever moving the cones as you say the forward engages before the indent is engages but the reverse indent cannot be reached.
 
I feel a dirty hands moment coming on

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Does the whole prop shaft slide forwards and backwards
using the prop thrust as servo??????

If there is no movement of the bits you can see is it possible the cones are on splines and have some for and aft play.

It sounds like something is not staying in place within the clutch cone assembly allowing one or other cone to come into contact with its cone and this will then possibly cause complete engagment.

No doubt it will all become apparent when you have the pieces laid out in front of you. /forums/images/graemlins/smile.gif
 
The parts diag. is not clear enough to see quite how it all works. So looks like the only way is to strip it. Hopefully it will be something like a bearing as the prices for major bits conform to the forum's views on V-P..........

To be continued.
Thanks all,
Andrew
 
Well, an update.
We stripped the g/box which was almost all in excellent condition. The tailshaft had two ball bearings, one of which had loads of play. Replaced it, actually reducing the motion still further(?) The cones are in good nick, but the prob is that there is virtually no play between the forward cone engaging and the same cone backing onto the reverse gear cone. The only possibility is that the lining material (sort of Ferodo) has swelled up? Turns out that the owner had run with hypoy transmission oil for a while. Could this have affected the linings?
In the absence of any owners here with experience of this, could anybody direct us to a Volvo mech with old knowledge.
Thanks,
Andrew
 
have the cones been relined? with the wrong material? too thick material?

i have found volvo technical to be very helpful in the past but whether they have an employee who knows such an old box ....................
 
WY, the linings appear to be the only variable in the equation. But, the box hasn't been touched for ten years min. We are trying a contact in Sweden, and I will see if I can get hold of Volvo tech.
Thanks from 'puzzled in france'
A
Tempted to machine a bit off the linings.....
 
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