port by means of a 3/8-inch ID hose that is at least 24
With 1,500 psi still applied to the PRESSURE
port, plug the BRAKE port, and then extend the valve
inches long. Position the reservoir in such a way that
shaft to midposition. Leakage from the RETURN port
the fluid is above (but not more than 6 inches) the
should not exceed 25 cubic centimeters per minute for
RETURN port. Move the shaft to the fully actuated
the last 4 minutes of a 5-minute period.
(2-inch plunger stroke) position, and then cap the
BRAKE port.
FLOW TEST.--To perform the flow test, you
should apply hydraulic pressure of 1,500 psi to the
To perform the pumping test, cycle the valve
PRESSURE port. Move the plunger between 3/8 and
rapidly. A rapid decrease in the length of successive
5/8 of an inch. Minimum flow at the BRAKE port
pressure strokes should be noted. On each cycle the
should be 2 gpm, and there should be no evidence of
return stroke should be self-motivated.
chatter or instability.
LEAKAGE TEST.--Reposition the unit on the
After testing is completed, remove the valve from
bench and harness the valve shaft in the midposition.
the test bench, flush it with hydraulic preservative oil,
With the RETURN and PRESSURE ports open,
drip-drain the unit, and plug all ports. The body should
hydraulic pressure of 25 psi should be applied to the
be rubber-stamped with the cure date of the oldest
BRAKE port. There should be no evidence of external
O-ring or packing and tagged with the date of the test
leakage, failure, or malfunction of any part of the
and the results.
valve. After the first minute, leakage at the RETURN
port should not exceed 1 cubic centimeter per minute
MASTER BRAKE CYLINDER
for 2 minutes. If satisfactory at this stage, repeat the
procedure by using 500 psi at the BRAKE port.
Maintenance at the organizational level consists of
With the valve in the relaxed position, apply static
removal and replacement of the master brake cylinder.
hydraulic pressure of 5 psi to the BRAKE and
Maintenance at the intermediate level consists of
RETURN ports. There should be no external leakage,
d i s a s s e m b l y, c l e a n i n g , i n s p e c t i o n , r e p a i r a n d
replacement of seals and parts, lubrication, reassembly,
failure, or malfunction of any part of the valve. Repeat
and testing.
the procedure with 200 psi of static hydraulic pressure.
Disassembly
Proof Pressure Test--Power Section
Before disassembly, the "Intermediate Repair"
A pressure of 2,250 psi should be applied to the
section of the MIM or 03 manual should be used to
PRESSURE port with the BRAKE and RETURN ports
make sure that all parts, material, equipment, and
open. Maintain the pressure for 2 minutes, and then
facilities required during repair are available.
look for evidence of external leakage, failure, or
permanent set. Perform this step twice.
WARNING
OUTPUT PRESSURE TEST.--This test is
Before any removal, install an AN350-4 nut on
performed in three stages. Apply hydraulic pressure of
the threaded end of the piston rod to bottom against
1,500 psi to the PRESSURE port, and apply successive
the shaft bearing. This will eliminate the possibility
plunger loads of 47 pounds, 124 pounds, and 190
of injury to personnel during disassembly because
pounds. As a result of these applications, the pressure
of spring preload.
output readings at the BRAKE port should be 100 to
160 pounds on the first load, 660 to 750 pounds on the
D i s a s s e m b l e t h e cy l i n d e r a c c o r d i n g t o t h e
second load, and 1,135 to 1,255 pounds on the third
procedures provided in the "Intermediate Repair"
load.
section of the MIM and/or 03 manual. Place
LEAKAGE TEST.--The leakage test for the
spring-loaded subassemblies in an arbor press or other
power section requires 1,500 psi of hydraulic pressure
device designed to restrain parts while relieving the
at the PRESSURE port with the BRAKE and
tension.
RETURN ports open. With the valve shaft in the
relaxed position, the combined leakage from the open
Cleaning
ports should not exceed 25 cubic centimeters per
minute for the last 4 minutes of a 5-minute period. If
Wash all reusable parts of the Gladden master
brake cylinder with P-D-680 cleaning solvent. Use a
the unit checks out, proceed to the next step.
14-21
