Simon.
I have been looking into the grease distributor theory the whole day, and I can not see any other device which fit into this handle. My theory is as follows one of the pipes end up at the shutoff cock before entering the grease distribution system. The system has to be straight forward and simple. On my sketch below I am showing my idea.The handle spindle is bored allowing grease under pressure to enter a space made by a lantern space ring on both side of the packing,(purple) thus entering the hollow spindle through the pressurehull and into a rectangular distribution box on the outside of the pressure hull. In the distribution box is a circular disc having bore in connection with the hollow shaft. The disc circumference have shallow bores, except the bore to the shaft, corresponding to the outlets of the distributionbox and the bores contains a springloaded ball acting as a shutoffvalve for the outgoing pipes at the same time providing notches of the disc movement. The idea is to have full control of the supply to the selected greasepoint and that no leakages is entering any other pipes except the selected, thereby ensuring the selected greasepoint is lubricated.
This ended as a long story, may be the sketch is easier to understand.
Tore