Don, you are entering into a complicated system consisting of hydraulic, pneumatic and mechanical elements with a lot of interlocks if you want to include the direct reversible system of the GW dieselengine, as you know the complicated direct reversible system was omitted as from 1943 on the GW engines. On the U 995 engines you `ll find only rudiments from of the direct reversible system. As to the starting system it works as follows, each cyindercover has a separate starting valve timed and operating from a modified camshaft by rollers,cams and pusrods. The starting valve looks like on my image below and consist of a common housing with a long valvespindle having a valve in the lower end, the chamber in the valvehousing has a direct connection to the startig air supply, the valvespindle goes through the startingairspindle chamber via the lower airtight springcarrier/ guide and a shutting spring up to the upper spring carrier. The upper valvespindle ends in an adjustable connection engaged to a springloaded lever connected to a valve rod ending in a roller arm. The startingvalve rocker system is kept free from the camshaft by a spring on the valve lever keeping the rollers away from the camshaft In the starting procedure starting air is admitted to the top piston of the startingvalve spindle, forcing the startingvalverod down agains the springload and engaging the roller to the camshaft, which operate the starting valve mecanically. When the starting sequence is over, air pressure on the valve spindle toppiston is vented and the starting valve spring lever is pulling the system free from the camshaft.
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