What is an OD box....???what is the purpose....???

oil distribution box is fitted on the intermediate shaft. A set of two aligned pipes axially located in the propeller shaft distributes the servomotor oil from the oil distribution box to the pitch changing servomotor located in the propeller hub.

The movement of the servomotor piston via hub setting mechanism changes the pitch of the blades. The hub internal mechanism is lubricated with oil from the gravity tank. The oil is distributed to the lubricating area of the oil distribution box via an axial hole in the shaft (outside of the two aligned pipes).

The propeller hub is fitted on the&nbsp;back end of the propeller shaft. The propeller shaft is connected with the oil distribution box shaft by a shrink coupling.<BR>In the hydraulic system there are two pumps (including a stand-by one) driven by electrical motors.

A special stop valve in the propeller shaft ensures maintaining a fixed pitch of the propeller when the oil pressure goes down. After stopping the main motor the pitch can be set at any position with the use of a manual pump.