(33-inch pitch diameter) sheaves will clear the inboard
(28-inch pitch diameter) sheaves.
The crosshead sheaves are made of an aluminum
alloy casting and have three sections: an inner race, a
cage and roller assembly, and an outer race. All the
sheaves in the crosshead and the fixed sheave
installation rotate on roller bearings with the exception
of the 28-inch pitch diameter high-speed sheave that
fairleads the purchase cable from the engine to the
flight deck. This sheave rotates on a ball thrust bearing.
The sheaves are separated by two-section concentric
disc spacers. Each spacer has an inner and an outer disc.
The inner disc is made of steel and provides lubrication
channels from the shaft to each cage roller assembly.
The outer disc is made of phenolic and acts as a bearing
surface for the outer sheave race; it also retains the
Phenolic spacers are bonded to the sheaves on the
high-speed side only. The low-speed side has loose
phenolic spacers. The sheaves are lubricated through
10 zerk fittings located on the end of each of the two
hollow steel shafts (20 zerks total).
The crosshead is provided with slipper liners as a
bearing surface between the crosshead and the
crosshead tracks. There is a total of 16 slipper liners2
on each side at the top, to prevent side thrust, and 3 on
each corner at the bottom, for a bearing surface. Brass
retainers hold the slipper liners in place.
construction to the crosshead, and all movable parts are
interchangeable. The fixed sheave assembly acts as the
stationary half of the reeve system and therefore does
not require liners. See figure 3-17.
AUTOMATIC LUBRICATION SYSTEM
LEARNING OBJECTIVE: Describe the
automatic lubrication system.
SHEAVE (28 P.D.)
SHEAVE (33 P.D.)
DEPTH GAUGE BRACKET
Figure 3-17.Fixed sheave assembly.