ll air lines for as many as three retract gear cylinders and three to six gear door cylinders can be attached to the Retract/Door Manifold. For example: Six individual air lines coming from the three retract gear cylinders can be attached to the manifold. Just decide which row of the captive nut fittings will be the retract gear up lines. The other row of captive nut fittings will be the retract gear down lines. The captive nut fittings on the front edge of the manifold will be power to the gear up and gear down rows of fittings. The other two rows of the smaller hose barb type fittings are attach points for the gear door cylinders.
The Retract/Door Manifold should eliminate most of the T-fittings which mess up installations and cause pressure drops throughout the system. The manifold is usually mounted near the central and lower part of the model or to the bottom of the fuselage. All lines from the retract gear cylinders and gear door cylinders will attach to the Retract/Door Manifold. In more complex installations with multiple gear door cylinders there can be as many as 18 individual air lines. Once organized and neatly attached to the fuselage and the manifold, these 18 air lines are now only 4 air lines of sometimes referred to as 4 circuits (Gear Up, Gear Down, Doors Up and Doors Down). These 4 air lines will pass upward and attach to the operating valves on the control board.
Shown in the photo the Manifold has 3 sets of retract gear cylinder fittings that are 4mm.
There are also 6 sets of 1/8” fittings for the gear door cylinders. Just about any number of attach fittings and air line sizes can be ordered.