Blower Drive and Coupling - TM-10-3930-242-340047

TM 10-3930-242-34

c. Disassembly. Refer to figure 3-9 and disas-

rotors. Use the blower rotor gear retaining bolts

s e m b l e the blower drive and coupling.

a n d plain washers to press the gears on rotor

shafts. Turn bolts uniformly until gears are

d. Cleaning a n d I n s p e c t i o n .

t i g h t against shoulder on the shafts. Remove

(1) Clean the blower drive and coupling

g e a r bolts, plain washers, and cloth.

components using a solvent such as P-D-680, or

(10) Place pilot (12) in counterbore of upper

equal.

g e a r and start bolt (11) into rotor shaft, Place

( 2 ) Inspect the gear and hub for wear.

r o t o r gear washer on face of lower gear, start

(3) Inspect support for scoring. See table

bolt into rotor shaft. Torque bolts to 25-30 ft. lb.

1 - 1 for engine wear and replacement standards.

(11) Check the backlash between the blower

R e p l a c e a defective part.

g e a r s . Backlash should be 0,005 inch to 0.0025

e. Reassembly. Refer to figure 3-9 and reas-

inch with new gears. Replace the gears if back-

s e m b l e the blower drive and coupling.

lash exceeds 0,0035 inch.

f. Installation.

( 1 2 ) The rotors, when properly positioned

(1) Refer to figure 3-8 and install blower

r u n with a slight clearance between the rotor

d r i v e and coupling.

l o b e s and with a slight clearance between the

( 2 ) Install blower assembly (para 3-5).

l o b e s and walls of the housing. The clearance

3-7. Governor

b e t w e e n the rotors may be established by mov-

ing one of the helical gears out or in on the shaft

a. General. The mechanical governor is

r e l a t i v e to other gear. Moving the gears out or

mounted on the rear end plate of the engine,

i n on the rotor is accomplished by adding or

T h e governor is driven by a gear that extends

r e m o v i n g shims between the gear hub and rotor

t h r o u g h the end plate and meshes with the bal-

spacers.

a n c e shaft gear. The governor controls the en-

(13) Measurement should be taken from

g i n e idle speed and limits the maximum operat-

b o t h the inlet and outlet side of the blower by

i n g speed of the engine. The governor is lubri-

i n s e r t i n g feeler gage between housing (25) and

c a t e d by oil splash from engine gear train dis-

rotors (22 and 23). Measurements should be

t r i b u t e d by revolving weights, Excess oil is re-

taken across the entire length of each rotor lobe

turned to the gear train through holes in the

to be certain that a minimum clearance of 0.004

governor bearing retainer.

i n c h exists at the air outlet side of the blower;

b . Operation.

a n d a minimum clearance of 0.0075 inch exists

(1) The governor holds the injector racks in

a t the air inlet of the blower. Similarly, the

the advanced fuel position for starting when the

c l e a r a n c e between rotor lobes should be meas-

speed control lever is in the idling position. Im-

u r e d across the length of the lobes. By rotating

mediately after starting, the governor moves

t h e gears, position the lobes so that they are at

t h e fuel injector racks to that position required

t h e i r closest relative position. Clearance bet-

for idling.

w e e n the lobes should be a minimum of 0.010

( 2 ) The centrifugal force of the revolving

i n c h . The blower rotor end clearances are 0.006

l o w and high speed weights is converted into a

inch for front end plate and 0.009 inch for rear

l i n e a r motion which is transmitted through the

end plate.

r i s e r and operating shaft to the operating shaft

f. Installation.

l e v e r . One end of the lever operates against the

(1) Refer to figure 35 and install the blower

h i g h and low speed springs through the spring

assembly.

cap, while the other end provides a moving ful-

(TM

filter

the

fuel

(2) Install

c r u m on which the differential lever pivots.

103930-242-12).

(3) When the centrifugal force of the revolv-

ing governor weights balances out the tension

o n the high or low speed spring (depending on

3-6. Blower Drive and Coupling

t h e speed range), the governor stabilizes the

a. General. The blower drive and coupling is

e n g i n e speed for a given setting of the speed

l o c a t e d on the air inlet housing side of the en-

c o n t r o l lever.

gine and is driven from an idler gear on the

(4) In low speed range, the centrifugal force

c a m s h a f t side of the engine.

o f the low-and-high-speed weights together op-

b. Removal.

e r a t e against the low speed spring. As the en-

(1) Remove the blower assembly (para 3-5).

gine speed increases, the centrifugal force of the

(2) Refer to figure 3-8 and remove the

low and high speed weight together compress

b l o w e r drive and coupling.

the low speed spring until the low speed weights

3-7