OK, so being a Hurth
, John is correct. There will most likely be a plate between the box and the engine. This is not always used on hydraulic boxes, although can be as it is the easiest way to connect the engine flywheel to the input spline of the box. But will normaly always be used for Geared boxes for the following reason. The plate can be called many names, such as "Drive plate", "Coupling Plate" but the proper name is the "Dampner Plate". The main job of this plate is to reduce a hammering effect from Diesel
Engines, called "injector shock". This "hammering" effect rattles the snot out of the internal gears of the box and can cause undue wear. I don't know if it could cause the clunk when placed in gear, but hey, I just don't know. With the Hurth box, there are clutch plates directly coupled to the gears. These plates are mechanicly operated as opposing to the Hydraulic box. The concept
is similar in both boxes, but the design and way it happens is very different. I suspect that the plates maybe grabing. This could be due to many possible reasons.
First would be to ensure you have good clean oil and at the correct level. ATF or Dex ll or lll is the recomended. Oil should be changed at 300hrs max and 100hrs if used a lot. But if you have had a severe load like had a rope
tangeld, then the oil should be imediatly changed.
The fill level on these boxes are measured with the stick just inserted, NOT screwed down. It is important the correct level is maintained.