TMP gearbox

[pcatterall]

We are back afloat following refit of a new propshaft and stern gear due to rope in prop damage.
We noted that the gearbox oil pressure was down a bit and decided to add a little oil though the dipstick level was ok and has been so for months.
Adding oil via what we ascertained from the Perkins manual had no effect!! we then realised that we were filling ( overfilling!!) the lower box which we had not realised was there!! We corrected this, got the oil to the correct level and added a bit to the 'upper' box so all seems to be ok!!

Questions
We assume that the upper box is the fwd/reverse gearing and that the lower box has the reduction gears ??
Is it the same oil ( engine oil) for both boxes?
Does the pressure Guage register one or both box's oil pressure?
Does anyone know if there is a manual available for these boxes?
I understand that TMP are still going strong, is it possible to get a recon unit on an exchange basis?
Will appreciate your help with any of these questions

 

[ffiill]

http://www.thameswaymarineproducts.co.uk/
They still stock full range of spares-you will also find a full set of cutaway diagrams with part numbers.They also stock the manual I believe.
If its like mine there is a reduction gearbox on the end with filler plug and as I recall a side level plug this is a conventional two to one or whatever reduction box
Behind that is the main gearbox with a filler plug on top near to the oil filter-mine has a dip stick to measure the oil level fed through the filler plug..
Both use engine oil.
The pressure guage reads the hydraulic pressure in the main box-hydraulic pressure holds together a couple of conical clutch plates -system should operate at about 80 psi.
Have you changed oil filter recently-on top of main box-they are a readily available filter from motor factors-no need to pay out a silly price.
Mine appears to have a slow leak through the front oil seal into the bell housing but just keep gearbox topped up.
If pressure guage is flicking about sign of low level of oil in main box.
Be warned it only takes a very small amount of oil between fill and full on my dip stick.
Thamesway Marine Products(TMP) do offer a recon service but the price when I checked it a few years ago was about £1500.
If your engine is about 50 hp or under you can get a new ZF Hurth or PRM mechanical for around £600!