The MK-II Oscillamatic Controller is a pneumatic pulser/timer used to operate the Williams series of pneumatically operated pumps.
The controller, consisting of an upper and lower chamber separated by a sliding spool, uses a capillary tube with a needle valve to transfer the supply air/gas from the lower to the upper chamber. While the controllers differ in their seals, MK-X using U-cup seals and MK-II, MK-VII, MK XIIA are using diaphragm seals, their operation is essentially the same. When the sliding spool is in its highest position, a pilot plug closes a vent and moves the supply air/gas to the pump or relay. In the spool’s lowest position, the reverse is true; the pilot plug prevents supply air/gas from entering pump or relay and opens the vent to let it exhaust. The spool then returns to its highest position and repeats the cycle.