Figure 4-10. Disassembly of vacuum pump 4931-929-8403.

TM 9-6685-202-14

Figure 4-10. Disassembly of vacuum pump 4931-929-8403.

j. Vacuum Pump 4931-929-8403, Replacement of

(5) Remove nine hex head screws (17) and

washers (18) from front plate (19) and back plate (33)

Springs, Vanes, or Pump Release. If the pump fails to

assembly.

function, the trouble usually can be attributed to a

broken spring or sticking vanes.

(6) Remove inner and outer rings carefully to

prevent vanes (41), springs (40), and spring holders (39)

(1) To inspect the springs or vanes, remove

from jumping out of the rotor slots. Do not allow the

screws from the belt guard and remove the guard.

vanes to be interchanged or reversed in position. Polish

Remove the belt. Loosen pulley setscrew (1) and

the vanes lightly with a fine grade of polish paper, if

remove pulley (2).

necessary, to remove corrosion. No metal should be

(2) Remove oil drain cap(50) and drain oil

removed during the polishing process.

from the case. Remove eight socket head screws (42)

(7) Reinstall spring holders (39), springs (40),

from center plate (26).

and vanes (41) in their original slots, making certain that

(3) Remove three fillister head screws (9)

they have not been interchanged.

from oil seal (3) and remove seal (3) and gasket (4).

(8) Reinstall front and back plates (19 and

(4) Remove center plate (26), inner ring (43),

33) with screws (17) and washers (18).

outer ring (37), intake chamber (30), and back plate (33)

(9) Reinstall center plate (26), intake

assembly from case (14).

chamber (30), front plate (19), back plate (33), inner ring

(43), and outer ring (37)

4-25