Technodrive TM170 TM880A, TwinDisk engaging failure, low hours

[MapisM]

Re: port gearbox works only on reverse

Question to ppl having gearbox oil pressure gauges on their dash (and a good memory!)
Do the values from idle to WOT change, if they do, do they change a lot?

I do have gauges, and even if for some reason my memory doesn't behave like good red wines (which get better over time! ), I can confirm you that it does NOT change a lot. Last summer, I kept a constant eye on all instruments during the delivery trip, and g/box pressure has always been the most constant parameter: 7 to 8 bar in neutral, and 23 to 24 bar with clutch engaged (in this respect, the values obviously change a lot, but surely that's not what you meant).
Btw, the (analogue) gauges are not accurate enough to distinguish differences of 1 bar, but I read in the ZF manual that these are the rated pressures, and the gauges were reasonably consistent with them.
Below is a manual abstract, which explains that the oil distributor is designed to keep the pressure constant regardless of rpm.
It's related to ZF 350 g/boxes, so surely different from yours, but I would think that the general principles still stand.
If by chance you are interested to have a look at the whole repair manual, I can email it to you - just ask.

 

[Portofino]

Re: port gearbox works only on reverse

reviving a 3yr old thread, apologies————-

In theory a 25bar sensor should do —————

Looks like it's safer to go for a 40bar sensor but the next cheap option is 60bar which is a bit too much I recon.

Any ideas?
Porto what does your MAN dash say on that? any pics?

cheers

V.

Idle about 5 bar after a run ie warm , running 19 bar
Twin disc 501 ,s with plane 30 W oil .

View attachment 75956

Got analogue guage as well on the dash calibrated so,s the needles point more / less vertical.

 

[vas]

Re: port gearbox works only on reverse

thank you P & PF,

interesting to see such variations in actual pressure.
yes I understand the theory that pos. displacement pumps manage a constant pressure over a range of revs, but not sure if anything else gets in the way, all these hydraulics are a bit cryptic (shouldn't be but I'm not confident with them as yet...)

I guess the 25bar should be OK, but generally not happy running something to its limits, so I'll get a couple of 40bar senders and use them in the middle of their range. Accuracy again should be much more than what I need anyway as it would be at least 1 decimal in psi!

cheers

V.