Lamborghini Formula Powerspeed problem

[Refco]

I have a silver Lambo Formula with a three stage powershift; snail, tortoise and hare. The other day, after some reasonable work, we found that when we put it in snail (the slowest) the gearbox locks up and the engine will stall if you don't dip the clutch.
The other two powershifts work fine.
Before I commit to putting the tractor in for what appears to be an expensive repair job, I just thought if any forum members might have seen this problem before and have a simple solution?
I am, by nature, an optimistic chap...

 

[Kevtherev]

Clutch pack has gone me thinks?

 

[Sheep]

Try getting it re calibrated, simple things first and all that.

 

[The_Swede]

Not sure about the three speed ones but on the two speed unit slow is 'mechanical drive' through the belleville washers whereas high needs hydraulic pressure - not sure if that's any help in this case. The only problem we ever had with one of these units was slippage after hard work - oil hot and so an internal seal leaking was the cause... yours sounds like the exact opposite. Sorry cant shed any more light than that except we pressure tested ours with an external gauge before comiting to having the box out.

 

[asm]

Low clutch pack burnt out.
Not a massive job

 

[Refco]

Thanks asm,
When you say not a massive job, do you mean it can be fixed without splitting the tractor?

 

[DrWazzock]

I don't about the three speed system but I would be checking all the external solenoids and switches (if it works on this principle) before I went any deeper.

Why would it lock up if a clutch pack was slipping?

Sounds more like two things engaged simultaneously when they shouldn't be. Stuck hydraulic control solenoid or coil broken, or control switch or circuit faulty?

 

[ridger]

It's trying to drive the 2 gears at the same time, when that happened ours it was because the brakes had gone and the filings stuck some valve or another

 

[asm]

Need to split and remove the bell housing.
Medium split is spring engaged while low and high are pressure engaged.
I would guess that low is starting to weld together.
As others have said check the solenoid valves first as that's easier and cheaper.