AN 01-25CN-2             PARAGRAPH 6
  NOTE:  
To prevent deterioration, remove and clean this seat each time power unit is removed from hub. Clean the contact points on hub and power unit.

  CAUTION:  
The contact points on the hub must coincide with the contact points in power unit. Place power unit over engine propeller shaft and against the hub. Secure the power unit to the hub wit4 the six attaching bolts and lock wire them together.

  (10) T6 ASSEMBLE POWER UNIT-LOW PITCH POSITION.

   (a) When placing a power unit in the hub, the power unit must he in low pitch position. If there is any question of this low pitch position, proceed as follows; as facing the power gear of the power unit, remove the three countersunk flat head screws and snap ring with a screwdriver. Remove the adapter plate and its gasket. At this point, the cam and contacts are clearly visible. (See Fig. 84.)    (b) If the low angle cam is not touching the low angle switch contact, the power unit is not in low pitch position.

  CAUTION:  
Unlock and remove the two mechanical low stop plug bolts and stop plug unit. (See Fig. 85.) This is done to prevent damage to the speed reducer, should the current carry the cam beyond the stop pin limit.

   (c) Using a 24 volt battery, touch one end of the battery lead to the low angle switch contact. With the other battery lead, make and break contact with the common return contact until the cam just touches the low angle switch contact as illustrated Fig. 84. The power unit is now in low pitch position. Replace gasket and adapter plate and fasten with the three counter. sunk flat head screw s. (See Fig. 84.)
  CAUTION:  
Replace the mechanical low stop plug with the mark "0" (or dot) on stop plug adjacent to mark "0" on housing. Replace stop plug bolts and lock wire together.

  (11) PROPELLER HUB LUBRICATION. 		         (a) Using the two zerk fittings alternately, fill the hub with No. 0 or No. 00 grease with a pressure gun. These two zerk fittings are located on the speed reducer (Power Unit) housing just forward of the front hub facie. (See Fig. 86.) Occasionally the grease relief fitting will stick, and as a precautionary measure, the relief fitting is removed to prevent an excessive pressure occurring in the housing resulting in bursted seals. (See Fig. 84.) Fill the hub uniformly, otherwise an air pocket may occur causing the grease to flow out of the relief fitting opening before the hub is completely filled. For craft operating in warm climates, it is advisable to use No. 2 grease. Replace . relief fitting after hub is completely filled.

   (b) POWER UNIT LUBRICATION.-Curtiss speed reducer oil No. 2 is used to lubricate the power unit assembly. This oil level must be checked every fifty hours. Check the oil level as follows: remove the filter plug located near the front of the housing. (See Fig. 87.) Rotate the propeller until the plug opening is approximately 20' below the horizontal center line of power unit assembly with the airplane at a ground angle of approximately 12'--or 8' below the horizontal center line when the airplane is leveled (tail up). In either of thew positions, the oil in the speed reducer should be visible at the plug opening, if not, fill at this plug opening until proper oil level is reached. Replace filler plug and lock-wire.

  NOTE:  
Use Curtiss speed reducer oil No. 2, Gargoyle aircraft instrument oil, or Aero Shell Fluid No. 6.

d. STARTING SYSTEM.

  (1) DESCRIPTION-live engine is cranked by a hand inertia starter, Type ". The hand crank must be removed before actuating the starter engaging mechanism.

  (2) REMOVAL.

   (a) Remove the 6 nuts which hold the starter to the mounting pad on the engine. Remove the starter engaging button from the cable by loosening the lock nut and unscrewing the button. Disconnect the booster coil conduit at the junction box on the firewall.