Figure 1-5. Gyroscopic reference unit

TM 5-6675-250-34

TM 5-6675-250-34

Figure 1-5. Gyroscopic reference unit - cutaway

condition of the follow-up shaft, the worm gear is

(1) The housing contains the follow-up shaft,

mounted with a preloaded pair of ball bearings. The

the servo gear train and the pendulum mechanism.

two speed gear head is provided to give the follow-up

The follow-up shaft is mounted to the housing

shaft ample angular velocity to track the pendulum

through a pair of preloaded ball bearings. The shaft

from 40 off of the meridian, yet have enough

engages a single lead worm at the gear train output

resolution to position the shaft as the pendulum is

through an anti-backlash worm wheel. This

damped to the meridian. Force for caging t h e

arrangement provides a locked condition of the GRU

pendulum is obtained through a lever which has one

output when the servo motor is de-energized after

end attached to the housing. The upper pendulum

gyrocompass is complete. The servo gear train is

caging seat is attached to the center of the lever and

mounted to the housing structure. It consists of a

the movable end of the lever is connected to a crank.

servo motor which drives a two speed gear head

The crank is mounted on a shaft which is rotated

which in turn drives the output worm through

through a worm gear. The gear is then driven by the

several spur gears. To assure the needed locked-up