est and Adjust Service Brake Hydraulic Accumulator Precharge Pressure

TM 10-3930-673-20-2

NOTE

Pressure reading obtained in Step (3) is the accumulator precharge pressure. Reading must be between

850 to 950 psi.

(4)

If precharge pressure reading observed in Step (3) is too low, add nitrogen to accumulator (1).

(a)

Connect nitrogen charging bottle to charging and gaging assembly.

(b)

Turn isolating valve on by turning valve counterclockwise and admit nitrogen into diaphragm of

accumulator (1). Do this slowly, checking pressure gage reading at regular intervals.

(c)

Repeat Step (4)(b) above as necessary, until precharge pressure is between 850 to 950 psi.

(5)

If precharge pressure reading observed in Step (3) is too high, bleed nitrogen from accumulator (1).

(a)

Open bleeder valve on charging and gaging assembly to vent nitrogen from accumulator diaphragm as

required. Leave bleeder valve open for only a short period and then close.

(b)

Check precharge pressure.

(c)

Repeat Steps (5)(a) and (5)(b) as necessary, until precharge pressure is between 850 to 950 psi.

(6)

Remove charging and gaging assembly from accumulator (1).

(a)

Close isolator valve by turning valve counterclockwise to a full stop.

(b)

Remove charging and gaging assembly from accumulator (1).

(c)

Install inner gas valve cap (9) and outer gas valve cap (8) with two screws (7) on accumulator (1).

NOTE

Air bubbles indicate nitrogen leakage. Any leakage must be corrected.

(d)

Brush a soap solution on and around inner gas valve cap (9) and verify that no air bubbles are present.

END OF TASK

12-27