Thwaites 1991 dumper lost drive

[Richard Lennard]

1991 Thwaites 4t 4x4 dumper.
Std gear lever in box, forward / reverse lever left-hand side of steering wheel.
Using all good - lost rev on lever
10 mins later lost all drive.
Have traced all electrics through, power as required at shuttle valve. Shuttle moving as desired.
Oil level good, but oil and filter haven't been changed in my ownership (25 years! )
Basically, everything appears ok but no drive.
Is it possible that shuttle isn't travelling sufficiently?
The dumper was behaving perfectly until this issue.
Found numerous little things, now repaired, on the way through checking.
Also, any idea what oil and approx capacity?
TIA Richard

 

[V8Druid]

1991 Thwaites 4t 4x4 dumper.
Std gear lever in box, forward / reverse lever left-hand side of steering wheel.
Using all good - lost rev on lever
10 mins later lost all drive.
Have traced all electrics through, power as required at shuttle valve. Shuttle moving as desired.
Oil level good, but oil and filter haven't been changed in my ownership (25 years! )
Basically, everything appears ok but no drive.
Is it possible that shuttle isn't travelling sufficiently?
The dumper was behaving perfectly until this issue.
Found numerous little things, now repaired, on the way through checking.
Also, any idea what oil and approx capacity?
TIA Richard

any pix of said beast?
bad earth somewhere perhaps?

 

[Mick-the-fitter]

Shuttle valve could be stuck due to oil glued up or moisture in it, ATF for the box.or in new machine UTTO!

 

[Richard Lennard]

Thanks. Only just picked up reply.
Does anyone have a breakdown of the shuttle valve?
I inverted the shuttle valve, connected electrically, all seems ok.
Murphy's law, could have been stuck and now isn't!