Nissan UD engines

i have a nissan UD4 in 1 of my old diamond T ,s , so ive been keeping an eye out for bits and pieces , so far ive scored 2 5 cylinder engines that i need some bits for , but today a aquired 2 UD4 engines for a parts trade off... ai was amazed at this strange contraption hanging out the back of the rocker cover , upon investigation ive found that it apears to be a exhaust brake. like a mechanical jake brake has any one ever seen this before



this is a normal set up

i know of a UD 2 stroke in a old thorneycroft prime mover ..

It looks like it would work on all cylinders at the same time so maybe a decompresor for shuting the engine down, just a thought.

Probobly be a good emergency stop Pat, as long as there was a bit of air pressure.

Well after having an indepth look in my UD4 workshop manual ....I can't find anything about that setup.

maybe it's a later ... after market......setup ??? I'm leaning towards maybe some sort of exhaust brake.

My reasons for this are as follows

If you look at the cyl on the outside it looks as if it pushes up and rotates the shaft so that the rockers lift off the valves......same as shutting the exhaust off with an exhaust brake.

If it were an engine shut off why would it have air lines going into both sides of the cyl ?? Wouldn't it be spring held off with air on so as to always be in the off position when theres no air ??

Any chance of some pic's of the rockers and shaft dismantled???

it does what you say werk , it shifts the pivot point in and out , in about a 30 degree of rotation ,so it might stop the valves from opening at all which i guess would act as a compression brake