transmission system, and figure 7-11 shows the
if one pump fails. The single planetary gear
reduces engine rpm to drive the rotary wing and
SH-60 transmission system.
accessories. See figure 7-13.
NOTE: Always refer to the applicable
A freewheeling unit, at each engine input to
MIM when attempting repair on helicopter
the main gearbox, permits the rotary wing to
systems.
autorotate without engine drag. The action
occurs in case of engine (or engines) failure or
MAIN TRANSMISSION GEARBOX
when engine rpm decreases below the equivalent
(SH-3)
of rotor rpm. The freewheeling unit also provides
a means of disengaging the rotary wing head while
The main gearbox mounts above the cabin aft
providing power to operate accessories.
of the engines. Its main purpose is to interconnect
the two engines in order to drive the rotary wing.
The accessory drive rotor lockout permits the
The main gearbox accessory section is at the
pilot to use engine power to drive the accessory
rear of the main gearbox lower housing. See
section of the main gearbox. This action occurs
figure 7-12. It drives the primary, utility, and
on the ground without rotating the rotary wing
auxiliary hydraulic pumps. It drives the high-
head. Power comes from the No. 1 engine only.
pressure torque meter oil pump, the No. 1 and
A switch allows the pilot to position the linear
No. 2 generators, and the rotary wing tachometer-
actuator and divert power to either the accessory
generator. Dual oil pumps are on the accessory
section or rotary wing. This switch, located on
the forward overhead switch panel, is marked
section. These pumps increase reliability through
better lubrication and permit continued flight
ACCESSORY DRIVE.
Figure 7-11.-SH-60 power transmission system.
7-14
